Abstract
The ever-increasing demand for low-carbon energy underscores the urgency of harvesting renewable energy sources. Despite notable progress, current energy harvesting techniques are still limited by low efficacy and poor durability. Biological systems exhibit diverse principles of energy harvesting owing to their ability to interact with the environment. In this Review, we explore diverse energy harvesting processes in nature to establish a fundamental understanding of nature’s strategies and provide a biomimicry design blueprint for high-efficiency energy harvesting systems. Next, we systematically discuss recent progress in nature-inspired surface/interface designs for efficient energy harvesting from water, sunlight and heat. We then highlight emerging hybrid approaches that can integrate multiple energy conversion processes within a single design through interface engineering to achieve mutual reinforcement. Finally, we deliberate on remaining fundamental and technical challenges to guide future research directions and potential applications of sustainable energy harvesting.
Key points
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Exploring diverse energy harvesting processes in nature to establish a fundamental understanding of nature’s strategies in energy manipulation.
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Probing nature-inspired surface regulation for efficiently transformating environmental energy source inputs to energy outputs.
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From the perspective of the phase state, summarizing interface engineering involved in water, sunlight and heat energy harvesting.
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Systematically discussing recent progress in nature-inspired interface designs for water, sunlight and heat energy harvesting.
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Highlighting emerging hybrid energy harvesting systems to achieve mutual reinforcement through interface engineering.
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Presenting perspectives on remaining challenges and future directions in nature-inspired interfacial engineering for energy harvesting.
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Introduction
The use of fossil energy has been a major contributor to rising environmental pollution and energy crises1,2. Tapping into the vast renewable energy sources such as water, solar and heat, sustainable energy harvesting has emerged as a low-carbon energy solution. However, most existing energy harvesting technologies are associated with low efficacy, poor durability and limited scalability, which are often dictated by the surface and interfacial properties of materials3,4,5. Nature is an engineer proficient in energy manipulation. Biological systems have orchestrated diverse strategies to harvest energy based on surfaces with well-defined interfacial properties to interact with surrounding sources such as water, sunlight and heat, achieving the highest energy efficiency with minimal materials6,7,8,9,10,11. Based on physics-guided design, nature-inspired interfacial engineering, which regulates surface properties of materials to control interfacial behaviours at multiple spatial–temporal scales, has been developed to harvest energy from diverse environmental sources.
In this Review, we provide a holistic view on a nature-inspired framework to guide the design, selection, fabrication and tailoring of engineered materials and interfaces, with the ultimate goal to develop advanced highly efficient energy harvesting systems. We first present an overview of energy harvesting processes in nature to provide a biomimicry design blueprint for artificial energy systems. Next, we discuss recent progress in translating these principles into nature-inspired interface designs for developing efficient energy harvesting technologies targeted at different energy sources, including water, solar and heat. We then highlight emerging hybrid approaches that can integrate multiple energy conversion processes within a single design to achieve performance with mutual reinforcement by interface engineering. Finally, we present perspectives on remaining fundamental and technical challenges to guide future research directions and potential applications of sustainable energy harvesting.
Energy harvesting in nature
Nature relies on interfacial interactions with the surroundings to harvest energy with high efficiency and minimal materials. Natural organisms can harvest and manipulate energy to facilitate a wide range of biological activities through diverse energy transformation, storage and even direct electricity generation. There are many examples in nature when sophisticated surfaces are used for efficient energy harvesting and electricity generation, including water-enabled energy harvesting, sunlight energy harvesting and storage, diverse bioelectricity generation and energy extraction in electrogenic bacteria.
Water-enabled energy harvesting in nature
Confined in a place permanently without the presence of muscles or nerves, plants and fungi in nature leverage dynamic water–surface interactions to achieve energy harvesting through the uptake or loss of water in response to environmental conditions. In this process, water serves as the primary medium for energy transformation, driving reversible or irreversible mechanical activities. One notable example is the self-burial seed of Erodium cicutarium12,13 (Fig. 1a). The self-burial is facilitated by the hygroscopic bilayer structure of awns in seeds, which enables spontaneous helical coiling and uncoiling in response to changes in dry and wet conditions, converting energy into mechanical motions that drill the seed into soil. A similar process has been found in other organisms such as pine cone and moss capsule peristomes that close and open in response to wet and dry conditions14,15.
Water-enabled adaptive energy harvesting also facilitates a wide range of irreversible mechanical momenta, achieved through continuous water uptake or loss on plants’ surfaces or hygroscopic structures. A typical example is Buller’s drop for diaspore ejection found in most species of Basidiomycota16,17. Formed by continuous condensation and coalescence of water on the hydrophilic surface, Buller’s drop can merge into the adaxial drop. The rapid flow of water induced by surface tension provides enough momentum to propel the spore off of the sterigma, converting the surface energy of condensed water into kinetic energy. Contrary to water condensation, water evaporation or dehydration in a dry environment could also generate efficient mechanical momenta, such as the explosive spore ejection of Sphagnum moss18,19 and the cavitation catapult of fern sporangium20. Central to these water-enabled energy harvesting mechanisms is the natural surfaces and structures that feature heterogeneous wettability, stiffness and charge, enabling intricate interactions with water. These natural features serve as a valuable inspiration for the development of efficient water energy harvesting systems21,22.
Sunlight energy harvesting in nature
Sunlight is the fundamental driver for energy flow, matter cycling and atmosphere regulation through photosynthesis, a process that converts sunlight into stored chemical energy that sustains most life23,24. Photosynthesis takes place in chloroplasts, where pigments absorb sunlight, triggering electronic excitation (Fig. 1a). Surface structures of photosynthetic organisms, especially in leaves and petals, present with complex textures such as subwavelength and hierarchical structures to promote sunlight harvesting by decreasing the loss of incident light and maximizing the absorbed light25. For example, petals of a rose leverage closely packed nanoscale papillae with broadband and omnidirectional anti-reflection as well as light-trapping capability26. Moreover, although photosynthesis does not directly generate electricity, it has inspired the development of photovoltaics that can directly convert sunlight into electricity. The surface structures and components of plants have inspired the design principle for dye-sensitized solar cells and organic photovoltaics27,28. The capability of oriental hornets to harvest sunlight by distinct cuticular pigments in their stripes29,30 offers valuable insights for the advancement of sunlight energy harvesting in photovoltaic technologies.
Bioelectricity generation in nature
Direct bioelectricity generation is a remarkable trait of electrogenic creatures, such as electric eels, electric rays and electric catfish, which can emit electric pulses with diverse frequencies, amplitudes and durations for predation, protection and detection. Typically, an electric eel can generate electric shocks of up to 600 V31,32 (Fig. 1a). Such powerful electrical discharge is emitted by the membrane proteins that are decorated with voltage-gated Na+/K+ channels in its electric organ. The Na+/K+ channels enable ion selectivity through the regulation of interfacial properties such as the molecular component, spatial configuration and charge distribution. Regulated by ion-selection channels, chemical energy is efficiently converted into ion gradient energy under the control of neural signals. Another type of bioelectricity is bio-piezoelectricity, originating from the piezoelectric effect that converts external mechanical stimuli into internal bioelectrical signals. Upon mechanical stimulation, a wide range of interfacial polarized tissues, such as keratin, DNA, tendons and elastin, generate bio-piezoelectricity, which plays an active role in physiological phenomena33,34.
In addition, as substantial microbial ecosystem engineers, electrogenic bacteria can generate electrical energy by extracting energy from the surroundings (Fig. 1a). Unique filamentous cable bacteria feature highly ordered fibre structures that can generate and mediate long-distance electrical currents across cell membranes, allowing for electron donor and acceptor harvesting in widely separated space35,36. In addition, some electrogenic bacteria manifest the ability to extract energy from the atmosphere, such as hydrogen37. Central to this diverse bioelectricity generation, ranging from selective ion channels to piezoelectric materials and electrogenic bacteria, is the sophisticated surface charge manipulation of biological systems. Taking inspiration from elegant surface charge regulations paves the way for sustainable electricity generation, including osmotic power generation, piezoelectric energy harvesting, moisture power generation and microbial fuel cells.
Surface and interface regulation in nature
Despite the diverse strategies used by biological organisms to harness energy from their environments, a common underlying feature is the evolution of surface properties enabling dynamic interaction with the surroundings to maximize energy efficiency. By regulating surface physico-chemical properties — wettability, surface charge, structure, heterogeneity and components – the input environmental sources, such as water, solar and heat, could be efficiently transformed into energy in the form of electricity, kinetic energy, chemical energy and thermal energy (Fig. 1b). Desert beetles, lotus leaves and water spiders manifest a wide range of surface wettability to regulate and rectify water surface energy, so that they can collect water from dry environments, repel water to self-clean and even gather air from underwater for survival38,39. Moreover, this ability can be further tailored and even amplified by surface topological structures, heterogeneity and components, giving rise to more versatile multiple spatial–temporal scales for preferential mass, momentum and energy exchange40. Surface charges, often neglected at the macroscopic scale, are another driving force for mediating liquid flow41 and can be harvested by electric eels to emit electric energy with varying frequencies, amplitudes and durations for predation, protection and detection.
Understanding, controlling and mimicking nature’s surface regulation and involved dynamic interfacial interactions also facilitates the efficient generation and transport of energy carriers (molecules, ions, charges and photons) at the microscale, which fundamentally shapes the macroscopic energy processes such as water fluidics, sunlight capture and heat transfer. The new insights learned from nature can prove instrumental for designing new energy harvesting systems42,43.
Tailoring interfaces for energy harvesting
Despite advances in the design of engineered systems, it is unlikely for one specific surface to address all of the challenges across multiple spatial–temporal scales in the complex energy harvesting processes. In this section we discuss recent advancements in nature-inspired interfacial engineering for energy harvesting from water, sunlight and heat. Energy harvesting technologies from each source are categorized based on the triple-phase interfaces for electricity generation, formed by the energy source and the surface of an energy device (Fig. 1c).
Water energy harvesting
The water cycle stores about 60 trillion kilowatts of energy each year, three orders of magnitude higher than the annual global energy demand. Conventional techniques mainly rely on hydroelectric turbines to collect high-frequency and centralized energy sources, such as river potential and tidal energy. However, a significant reservoir of water energy stored in decentralized and low-frequency forms, such as evaporation, osmosis, moisture and raindrops, remains largely untapped. The past decade has witnessed a surge in exploiting various technologies for harvesting these underutilized water energy sources, including hydrovoltaic technology4, reverse electrodialysis44 and triboelectric nanogenerators45 (Fig. 2a). All these approaches rely on the manipulation of interfacial electric charges through interaction between water and interfacial materials46,47. Despite progress, achieving water energy harvesting with high efficiency, scalability and high durability remains challenging, partially owing to the lack of rational design of the interface and material design. To tackle this challenge, natural living organisms — especially their intriguing surfaces — can serve as inspiration for material design.
Water energy harvesting via hydrophilic surfaces
Generating electricity from water energy sources through osmosis, evaporation and moisture requires a durable and intimate water–material interface to facilitate the continuous charge generation and ion redistribution. Such interaction has been found in various natural hydrophilic surfaces. As a result, many nature-inspired hydrophilic surfaces have been developed and applied in water energy harvesting technologies.
Water energy stored in the salinity difference between seawater and river water, referred to as blue or osmotic energy, has an estimated power density of 0.8 kWh m−3 at the sea–river interface48. Current osmotic energy harvesting mainly relies on two strategies: pressure retarded osmosis and reverse electrodialysis. Between the two, electrodialysis has received increasing attention owing to its lower operating pressure, broader applicability and greater stability49,50. Reverse electrodialysis generates electricity leveraging the ion diffusion process across a semi-permeable membrane between salinity-gradient water, which can result in charge separation and an electric potential difference. Conventionally, the ion-selective membrane serves as the core material for reverse electrodialysis owing to its abundance, large area and high ion selectivity51,52. However, such a design suffers from limited power density, mainly because the ion-selective membranes feature sub-nanometre scale pores comparable with the size of ionic species and large thickness (several hundreds of micrometres). These features weaken the ion transport due to the high ion resistance and charge polarization occurring at the membrane–solution interface, and easily lead to fouling from environmental substances such as heavy metals, biological pollutants and large organic chemicals53,54.
Inspired by the biologically structured ion channels that can transport ions at a large flux of 107 ions per second55 (Fig. 2b), the strategies for osmotic energy harvesting have shifted towards designing various nanofluidic channels, which feature larger channel dimensions and highly charged surfaces. The nanofluidic channels give rise to the enhanced ion flux in diffusion-osmotic flow, low charge polarization and resistance to environmental fouling, thereby enhancing electricity generation56,57 (Fig. 2c, left). By optimizing parameters such as geometry, surface functionalization and size, the nature-inspired nanofluidic membranes can selectively transport specific ions, which improves ion separation efficiency and, thereby, energy harvesting performance58,59. Theoretically, the nature-inspired nanofluidic membranes can improve the power density of the osmotic energy harvesting technology up to 106 W m−2, much higher than the ion-exchange membrane-based design32,56,60 (Fig. 2d). Moreover, the design of nanofluidic channel-based membranes offers better suitability for large-scale integration owing to the inherent flexibility and layered structures61. Currently, nanofluidic channel-based osmotic energy harvesting is still at the laboratory stage and has not been widely used in practical scenarios52. Presently, practical applications are limited by the trade-off between selectivity and flux, performance saturation when scaling up and the lack of simple fabrication methods.
Evaporation is a ubiquitous phenomenon that drives energy transfer in the Earth’s climate. However, harvesting energy from evaporation remains challenging owing to the lack of explicit working principles and reliable devices. One possible strategy is to harness the energy stored in evaporation from water-responsive material deformation62 or interfacial ion transport63. Leveraging the advances in nanomaterials, harvesting energy from the evaporation-induced interfacial water/ion flow has become a leading generic strategy with high adaptability to various environments64,65 (Fig. 2c, right). Facilitating continuous water and ion transport with high flux and density requires a surface design characterized by high hydrophilicity, ionizability, durability and a large surface area46,66. However, meeting all these requirements is difficult for conventional nanomaterials, most of which focus one or two aspects of the requirements for surface design.
Addressing this challenge can be done by mimicking natural organisms’ interfaces and materials. Materials with plant-inspired hydrophilic structures such as hierarchical and capillary channels feature a large specific surface area and high hydrophilicity, facilitating the water/ion transport flow for electricity generation67. Moreover, by taking inspiration from adaptive natural leaf structures such as stomata68, surfaces capable of adapting to environmental change for efficient water/ion transport can be designed. Another approach for energy harvesting enhancement involves surface chemical modifications with active chemical groups to intensify the water–material reactions, which can increase ion density at the interface69,70. In addition to biomimetic materials, some biomaterials, such as cellulose and microbial film, with sufficient functional groups and porous structures, are suitable for evaporation-induced energy harvesting with environmental compatibility and renewability71. Although nature-inspired designs hold promise for enhancing evaporation energy harvesting, the interplay of various characteristics such as channel size, wettability and surface potential hinders identifying the specific sources of performance optimization. Therefore, it is critical to establish relationships between material properties and output power for guiding materials and interface design.
Ambient moisture is a tremendous natural energy source that can be harnessed through moisture-induced energy harvesting technologies. Techniques based on moisture-responsive materials can convert moisture into mechanical energy or chemical energy, and generate electricity by integrating with the piezoelectric effect21, the electromagnetic effect22 and redox reactions72. However, these approaches are limited by the extremely low energy density and complicated fabrication. The thermodynamic process of ambient moisture absorption by sorbents presents a controllable and sustainable method to harvest green energy from moisture73. This strategy relies on electricity generation by constructing asymmetric ion diffusion in the absorbent materials with a gradient or homogeneous structure73,74 (Fig. 2e). These moisture energy generators still suffer from a low power density (0.1 W m−2) and non-self-sustainable electricity generation owing to the low ion migration velocity and gradient invalidation.
Drawing inspiration from surface heterogeneity found in nature, designing materials with heterogeneous physico-chemical properties could be a promising solution. By imitating the heterogeneous lipid bilayer found in the cell (Fig. 2f), a moisture-based generator with a charge-heterogeneous structure can be constructed showing higher energy conversion efficiency and power density because of highly asymmetric ion movement75,76 (Fig. 2f,g). For example, a bilayer membrane composed of negatively charged PSSA and positively charged PDDA can produce a power density of 0.5 W m−2 and a voltage of 1,000 V with integration design at 85% relative humidity, which is several orders of magnitude larger than the voltage from other designs75. Furthermore, introducing heterogeneous wettability into sorbents enables a balance between hydrophilic adsorption and hydrophobic desorption of moisture, thereby preventing the sorbents from total wetting and achieving self-sustainable electricity generation77,78. In addition to the heterogeneous material design, the direct usage of biomaterials, such as protein nanowires, spider silk and microbial film, allows for developing moisture energy harvesting, which is cheap, non-toxic and environmentally friendly79,80,81,82. Nevertheless, moisture energy is essentially a low-grade energy with a theoretical upper limit of 10% on its efficiency. Reaching or even breaking this limit calls for the disruptive design of materials and designs.
Hydrophobic surfaces for water energy harvesting
Hydrophobic surfaces have a low affinity for water, enabling transient contact and separation with water. This type of water–material interaction enables an interface transition and stronger charge redistribution than that on hydrophilic surfaces, making hydrophobic surfaces suitable for harvesting water from droplets and waves.
The triboelectric nanogenerator83, reverse electrowetting84 and drawing potential85 are examples of hydrophobic surface-based water energy harvesting techniques. From the circuit architecture perspective, these generators can be treated as an open-circuit system, which brings about several drawbacks including the limited charge generation and the unwanted electrostatically screening effect imposed by the charges on the underlying electrode, which is a component for outputting electricity in typical triboelectric nanogenerators and reverse electrowetting.
One feasible strategy to overcome these limits is to use an architecture that can form a closed loop between the hydrophobic electret material, two electrodes located below and above the dielectric layer, and dynamically flowing water. The design is inspired by that of a field-effect transistor, which can dynamically gate the flow of carriers between its source and drain terminals3,47 (Fig. 3a). The water energy generator with transistor-like architecture can fully harness the surface charge on the hydrophobic surfaces and generate electric outputs with an energy conversion efficiency three orders of magnitude larger than the conventional triboelectric nanogenerator and reverse electrowetting. The transistor-like design concept provides a possibility to generate electricity from a single droplet to droplet arrays86,87, from natural rocks to artificial windows and solar panels87,88, with continuous leaps in peak power density from 50 W m–2 to 105 W m–2 (refs. 89,90).
The performance of hydrophobic surface-based water energy harvesting is dictated by the interfacial properties of generator materials as well as their interaction with the liquid. Efficient and continuous electricity generation necessitates a high-density interfacial charge, a large liquid–solid contact area and rapid detachment of water from the generator. However, most hydrophobic surfaces feature a two-dimensional (2D) contact with water that leads to a low surface charge density and a low water–surface contact area. Moreover, the high-frequency contact of water on these surfaces may cause the formation of a continuous water film because of the long water–solid contact time, thereby disabling the continuous electricity generation.
One way of addressing these issues is to design a lotus-inspired superhydrophobic surface (SHS)-based water electricity generator91,92,93 (Fig. 3b). The hierarchical structure of the SHS enables a three-dimensional (3D) contact with water, resulting in a large water–surface contact area and a high surface charge density. Moreover, the SHS can shed water within several milliseconds because of its water-repellent properties, thereby allowing high-frequency water energy harvesting. For example, the lotus-inspired water energy generator can generate three times higher average electrical energy from a 165 Hz droplet than that of a generator with a conventional hydrophobic surface91. Other superhydrophobic designs mimic the hierarchical nanoscale and microscale natural surfaces such as moth eyes and bamboo leaves, or natural surfaces such as leaves and stones94,95.
Operating in various working conditions, solid hydrophobic surfaces are susceptible to external pollution and unwanted wetting transitions caused by hydrodynamic impact in extreme environments. More challenges emerge in the underwater condition. The hydrophobic surfaces face the high pressure and flow shearing from surrounding water, as well as the biofilm fouling. All these problems could result in the collapse of efficient contact and separation between water and the hydrophobic surface, impairing energy harvesting efficiency and durability.
Mimicking natural liquid surfaces that can repel immiscible liquids with high stability provides a feasible solution for designing hydrophobic generators with a liquid dielectric surface to enable liquid–liquid contact with water (Fig. 3b). Choosing dielectric liquid with proper viscosity and a dielectric constant, the liquid–liquid contact between water and the generator surface eliminates the unwanted wetting transition and increases the effective liquid–solid contact area, all of which are beneficial for water kinetic energy harvesting96,97. For example, inspired by the pitcher plant, slippery liquid infused surface (SLIPS)-based water energy generators show a stable electrical output in a wide spectrum of harsh environments, ranging from high salinity to caustic acid–base, in a wide humidity and temperature range97,98,99 (Fig. 3c).
Although harvesting energy from water in the air provides an alternative energy harvesting strategy, this approach becomes ineffective in the offshore condition due to off-grid conditions and limitation of long-distance electricity transmission cables. One option is to harvest energy directly from bubbles in the underwater environment. However, the hydrophobic generator surfaces that function well in the air may break down when a continuous interfacial water film forms in the confined underwater environment, screening surface charges stored on the dielectric surface.
The design of surfaces for bubble energy harvesting draws inspiration from natural aquatic plants, such as water hyacinths or water lilies, that can store and transport gases in the water through their surface. Delicately tailored surface wettability endows dielectric surfaces with high-density surface charges which facilitate fast bubble spreading and subsequent departure in the process of liquid–solid interface transformation into a gas–solid interface. This interface transition allows for efficient charge transfer and electricity generation in a water environment100,101 (Fig. 3b). In conjunction with the transistor-like design, a bubble energy generator with the optimal dielectric surface can yield an output at least one order of magnitude higher than the control studies without a surface control (Fig. 3c). However, the durability of a solid surface is susceptible to the harsh underwater environment that can lead to surface fouling and wetting transition. Potentially, the usage of a liquid dielectric surface with delicately controlled wettability could improve the stability and lifetime of the generator for applications in underwater and offshore operations where direct energy harvesting from small bubbles is otherwise impossible.
The fusion between the nature-inspired interface design and transistor-like architecture has formulated a genetic design concept that dramatically enhances electricity generation at various interfaces. (Fig. 3d).
Solar energy harvesting
Solar energy is the largest and inexhaustible natural energy source. Among myriads of solar energy harvesting processes, solar or photovoltaic cells are capable of directly converting sunlight into electricity via the photovoltaic effect. The operation of solar cells relies on sunlight harvesting and subsequent internal processes involving the generation, transport, separation and collection of charge. From the perspective of interface engineering, sunlight harvesting process at the gas (air)–solid interface involves intricate light–surface interactions between sunlight in the air and interfacial materials (Fig. 4a). Driven by advances in sunlight harvesting materials and fabrication, solar cells have undergone an impressive transition, from initially crystalline silicon solar cells to perovskite solar cells (PSCs), from single junctions to multi-junctions/tandems, making it possible to continuously break current efficiency limits102,103.
Despite intense progress, existing solar cells still suffer from limited power conversion efficiency (PCE) and insufficient durability, especially when working in a harsh environment5,104. More challenges arise with the growing power demands of portable and wearable electronic devices, which necessitate more stable and optimized integration105. One possible solution to tackle these challenges lies in the design of nature-inspired surfaces that can regulate light–surface interactions to enhance sunlight harvesting, achieve optimal carrier dynamics and optimize device integration as well as improve long-term stability and durability. In this section, we focus on discussing recent advances in optimizing solar cell performance through interface engineering, from the aspects of nature-inspired structural design for sunlight harvesting capability and nature-inspired surface design for enhanced stability (Fig. 4b).
Nature-inspired structural design for sunlight harvesting
The efficiency of sunlight harvesting of solar cells is closely dependent on the structure. Conventional solar cells usually exhibit relatively smooth non-textured structures, which is partially due to the fabrication process and materials used. Despite facile manufacturing and low processing cost, these non-textured structures restrain efficient light–surface interactions, leading to high optical losses and low sunlight utilization. Ideal sunlight harvesting structures necessitate optimal light–surface interactions that contribute to broadband light absorption, minimized light reflection losses, enhanced light trapping and so on. Inspired by excellent light management in the surface structure of moth eyes, butterfly wings and petals of flowers10,25,106,107, three types of biomimetic structures have been extensively utilized to maximize sunlight harvesting (Fig. 4b), including designing subwavelength structures to minimize surface reflection, hierarchical micro/nanoscale textures to enhance light trapping and other multiscale structures for enhanced sunlight absorption.
Highly ordered nanostructured pillar arrays are a representative subwavelength structure with characteristic sizes smaller than the incident light’s wavelength, which can control light propagation to minimize reflection, creating anti-reflective surfaces that enhance light absorption in solar cells106,108. To enhance light trapping, hierarchical microscale/nanoscale textures have also been engineered, which is beneficial to increase the path length of light and facilitate multiple reflections and scattering of light within the active materials, contributing to efficient sunlight absorption107,109. As a step forward, distinct from the above structures, a more elegant approach is to leverage multiscale structure with diverse dimensions and textures. Despite their different functions, these structures interact and complement each other to optimize light propagation and interactions for maximum solar energy harvesting. For example, sunlight harvesting structures that mimic the surface structures of rose petals and viola flowers enhance the PCE of solar cells by 13.7% and 6.2%, respectively, compared with flat and untextured counterparts26,110. It is anticipated that nature-inspired structural design offers a new dimension in regulating light management for efficient solar energy harvesting, particularly with the rapid development of multi-junction or tandem solar cell devices involving multiple interfaces.
Nature-inspired surface design for enhanced stability
Achieving high efficiency and long-term durability of solar cells is crucial for their practical deployment. Operating outdoors, conventional solar cells are easily susceptible to the deposition and accumulation of dust, water and moisture on the surface, which significantly compromises the stable output power and requires frequent cleaning111,112. Further performance degradation can be accelerated by moisture-induced lead leakage in lead halide PSCs, ultimately causing device failure and even environmental pollution113,114. Moreover, the operational stability of solar cells is affected by the dynamic changes of natural light throughout the day, which causes energy-density loss and fluctuation in output power. These issues can be mitigated by regulating surface wettability and adaptability of solar cells. Inspired by natural superwetting surfaces, a wide range of strategies have been developed to endow solar cells with self-cleaning capabilities to ensure high energy efficiency and long-term durability (Fig. 4b).
Inspired by high roughness and low surface adhesion of surfaces in lotus leaf, external surfaces of solar cells decorated with water-repellent coatings can effectively prevent surface pollution and, thereby, ensure stable operation112,115. The inherent water-repellent capability helps seamlessly integrate solar panels with water-based electricity generators, which requires timely shedding of liquids from the dielectric surface. Combining solar cells with water-based electricity generators enables energy harvesting in all-weather conditions116,117,118. Apart from the wettability regulation on the external surface of solar cells, it is equally important to tailor the wettability of internal interfaces for some PSCs. By controlling materials, structures and chemistry at the molecular level, the design of interface wettability can further reduce surface defects and establish interface shields that effectively mitigate environmental-induced degradation and failure, ensuring long-term stability and durability119,120. One remarkable example is superhydrophobic engineered PSCs, which retain 90% of their initial efficiency during photovoltaic operation for 1,000 h at 40% relative humidity, in striking contrast to the untreated samples that rapidly drop to 43% efficiency under the same conditions121. Mimicking nature’s adaptivity, such as the phototropism of sunflowers that can self-orient towards the sun to maximize sunlight exposure, adaptive solar cells with sunlight-tracking have been developed122,123. Capable of dynamically sensing and responding to changes in natural light, adaptive solar cells achieve stable efficiency throughout the day, contributing to enhanced energy harvesting performance. Using these strategies, performances of the solar cells (Fig. 4b) can be improved through nature-inspired engineering.
Heat energy harvesting
Approximately 67% of energy is wasted as heat124,125. Tremendous efforts have been dedicated to developing thermal energy harvesting technologies to capture, store and utilize waste heat, including molten salt technology, thermal chemical storage and thermal power generation126,127,128. However, these technologies rely on bulk volume and only work with high-temperature thermal energy, leaving decentralized and low-grade (<100 °C) heat energy largely unexplored129,130. To this end, thermoelectric generators (TEGs) have emerged based on different mechanisms such as the Seebeck, Peltier and Thomson effects, by which thermal phonon motion from the external medium is converted into internal ion and charge movement for electricity generation131,132,133 (Fig. 5a). These mechanisms have led to the raid development of TEGs with various modes, including the typical TEG (thermoelectric effect)134,135, the pyroelectric generator (pyroelectric effect)136,137 and the thermogalvanic generator (thermogalvanic effect)138 (Fig. 5b). Despite intensive progress, current TEGs still suffer from low energy efficiency, limited scalability and inadequate durability. Nature-inspired advanced interfacial designs may offer new possibilities to meet requirements for highly efficient heat energy harvesting139,140,141,142. In addition, waste heat is commonly stored in liquid and solid, underscoring the crucial role of the interface between the TEGs and the thermal medium in enhancing TEG performance.
Nature-inspired liquid–solid interface
Waste heat in the form of liquid is ubiquitous, ranging from the vapour exited from nuclear power plants to the cooling water used in steel mills. Unlike the intensive exploration of advanced materials for TEGs, less attention has been placed on the interfacial interaction between TEGs and hot liquid mediums (Fig. 5c). Interfacial interaction, however, is an important factor that directly affects heat transfer, ion separation and charge migration, influencing the performance of TEGs130,140. First, the high fluidity and deformability characteristics of liquids facilitate convective heat transfer and ensure stable voltage output. Liquids can seamlessly adapt to various heat transfer surfaces regardless of shape, composition and size with maximal contact area and minimal thermal resistance. Moreover, being excellent carriers of ions, liquids can decrease the ohmic resistance at the solid–liquid interface and generate electrical power through electrochemical redox reactions for harvesting low-grade heat143.
Specifically, nature-inspired super-hydrophilic surfaces can significantly expand contact surfaces and reduce thermal resistance between liquid–solid interfaces, thereby promoting heat transfer144,145. Incorporating functional coatings, that is, dynamic thermoregulatory material inspired by squid skin146, on the surface of TEGs can also facilitate heat conduction and prevent surface oxidation and corrosion, resulting in improved durability (Fig. 5d). Apart from surface modification, the internal structure manipulation of TEGs, such as the utilization of wood-derived porous cellulose membranes147, endows the TEGs with larger accessible surface area, shorter heat transfer path and optimized integration to ensure high energy conversion efficiency (Fig. 5e). In addition, structural chemical components in TEGs further contribute to improving the heat harvesting capability as evidenced by the radiative cooling materials inspired by desert silver ants148. The triangular shape of the silver hairs can increase the reflection of near-infrared rays to dissipate heat in the dry and hot environment (Fig. 5f). Overall, these strategies, despite their different functions, interact and complement each other to optimize heat transfer and harvesting for maximum heat to electricity conversion.
Nature-inspired solid–solid interface
Effectively harvesting waste heat stored in solid mediums is critical for many industries such as electronics, automotive, aerospace, power generation and directed energy systems. Current solid-state TEGs are capable of harvesting waste heat for electrical generation; however, their practical application is hindered either by low conversion efficiency or complex design. From an interface perspective, these shortages arise from the mismatches of lattice and surface topology between TEG materials and hot mediums (Fig. 5g). First, the lattice mismatch between TEG materials and hot mediums may induce energy barriers and inhomogeneous thermal expansion, both of which hinder heat transfer. Furthermore, the utilization of high-temperature heat mediums (>1,000 °C) necessitates more stable TEG materials to prevent oxidation, deformation or even cracking and melting149. Second, the surface topology mismatch between TEGs and heat mediums introduces unwanted air gaps that hinder their conformable contact and degrade heat transfer and charge migration.
Mitigating the above mismatches necessities nature’s strategies to efficiently regulate the microstructure and composition of TEG surfaces. One potential solution is choosing flexible TEG materials to construct compatible solid–solid interfaces, thereby reducing the heat transfer resistance. For example, the utilization of stretchable and adhesive hydrogels as conformable thermal interfaces presents a promising solution for effective heat transfer and enables compliant designing of TEGs in complex application scenarios150,151 (Fig. 5h). Another feasible approach is to introduce functional coatings as intermediate layers between heat sources and TEG materials to reduce thermal radiation losses and improve thermal energy conversion efficiency. One typical example lies in hollow structured thermal insulating materials inspired by polar bear hairs152. Additionally, the excellent processability of solid materials allows for the microscale design of TEGs, making them suitable for emerging applications such as the Internet of Things, wireless sensor networks and microelectronics153. In particular, they can be seamlessly integrated into flexible wearable devices to power advanced low-energy electronic devices154,155,156 (Fig. 5i). TEGs with distinct working mechanisms have their operation temperature ranges (Fig. 5j). Among them, the TEG demonstrates a relatively higher energy conversion efficiency (η) of around 13%, followed by the thermogalvanic generator (7.8%) and the pyroelectric generator (3.4%).
Hybrid energy harvesting
Nature-inspired interfacial design has reshaped the way of harvesting individual energy sources such as water, sunlight or heat. However, in most scenarios, these energy sources coexist and can be mutually converted. Harvesting these energy sources in a hybrid manner offers the potential to overcome the intermittency of individual energy harvesting (Fig. 6a). Current strategies mainly rely on the simple stacking of different individual energy harvesters, which may sacrifice the advantages of individual energy harvesting and even lead to lower overall efficiency. An ideal design of hybrid energy harvesting should achieve mutual reinforcement in individual performance, thereby leading to collective benefits, such as low cost, increased space utilization and energy conversion efficiency, as well as enhanced availability and stability.
One solution is to seamlessly integrate water–sunlight–heat energy generators through rational interface design and material optimization. To this end, the characteristics of each energy harvesting process should be carefully considered for optimized collective performance (Fig. 6b). For example, integrating a SHS-based water energy generator with a photovoltaic cell provides superior self-cleaning, anti-reflection and longer operation time87,116,117. A similar interface engineering principle enables hybrid water and heat energy harvesting, in which the kinetic energy and latent energy of water can be fully utilized157,158,159. Integrating a photovoltaic cell and a TEG with a common interface can simultaneously improve the temperature difference of the TEG and cooling efficiency of the photovoltaic cell, facilitating the mutual enhancement in energy harvesting efficiency142,160,161. By harvesting multiple energy sources in a parallel manner, these hybrid energy generators can also improve energy utilization efficiency, energy reliability and stability, and provide cost reduction.
In addition to parallel energy harvesting, optimizing the generator surfaces also enables hybrid energy harvesting leveraging the serial energy transduction (Fig. 6c). For example, designing interfaces containing photothermal and radiative cooling materials can collectively generate thermal gradients or fluctuations for thermoelectricity generation, enabling all-day energy harvesting from both the sun and outer space162,163,164. In addition, the sunlight to water energy conversion can harvest energy through integration of photoelectric materials and the ion-selective membrane, synergistically converting the sunlight energy and salinity gradient into electricity165,166. Moreover, the coexistence of sunlight, heat and water sources in the natural environment can facilitate multiple energy transductions via a highly integrated hybrid system (Fig. 6d), allowing for weather-adaptive energy harvesting in one scenario.
Nature-inspired interfacial engineering in individual energy harvesting paves the way for the springing out of hybrid systems with mutual reinforcement. Promoting these hybrid designs in practical applications faces more challenges owing to mismatch in the forms and scales of electrical output produced by different energy generators. We envision that a combination of interdisciplinary technologies such as intelligent electronic control, energy storage and management can solve these problems, enabling maximum utilization of various energy sources.
Outlook
Learning from the ways energy is utilized in nature through the evolution of surface engineering has provided ample opportunities to achieve sustainable electricity generation with high efficiency (Table 1). However, more scientific effort is required to reveal underlying mechanisms in diverse energy processes.
Translating nature’s inspiration to practical applications calls for the innovative fusion of multidisciplinary fields. Firstly, despite extensive progress, the basic mechanisms underlying electricity generation from different resources remain to be fully clarified. For instance, the charging mechanism of triboelectric nanogenerators is still under debate regarding whether it involves electrons, ions or mass transfer167. The processes occurring at diverse interfaces and displaying distinct spatial–temporal scales are strongly related to the local physico-chemical properties of interfaces, such as wetting, structure, surface charges, heterogeneity and composition, which together dictate the global behaviour, the energy efficiency. Although energy efficiency is easy to measure and quantify, a holistic understanding is elusive owing to its complexity imposed by the multiscale processes. Therefore, a combination of advanced techniques in manufacturing, characterization, visualization and modelling as well as the latest toolkits in machine learning is needed to accelerate the in-depth fundamental exploration168.
Translating our fundamental understandings into practical applications presents several challenges. Nature-inspired interfacial engineering has led to energy efficiency enhancement; however, the precision as well as functions of current engineered interfaces are not yet comparable with their biological counterparts. Further scaling up as well as the development of hybrid energy harvesting systems may compromise reproducibility, compatibility and reliability of engineered interfaces. Addressing these challenges necessitates innovations in material design, manufacturing and soft technologies, such as artificial intelligence, molecular dynamics and smart energy management algorithms. This approach will accelerate the miniaturization of energy harvesting systems, which can be seamlessly integrated into self-sustained electronic devices, including wireless sensors and wearable electronics for a wide range of fields such as environment monitoring, infrastructure health management or space exploration169,170. Moreover, these innovations can facilitate the scaling up of energy harvesting systems for utility-scale applications, especially in remote or offshore regions with abundant natural resources but limited access to electricity. In addition to enhancing their ability to effectively harness abundant natural sources such as water, solar and heat, it is possible to achieve mutual reinforcement of hybrid energy harvesting systems for sustainable electricity supply, particularly in emerging fields such as the Internet of Things and smart farming.
The advances in nature-inspired interfacial engineering have demonstrated immense potential in the design of new materials and devices to harvest multiple energy sources, paving the way for sustainable electricity generation at multiple spatial–temporal scales and scenarios. Projecting to the future, our continued venture into nature through the innovative convergence of multidisciplinary fields can, potentially, lead to transformative and highly efficient energy harvesting systems. These advancements would hold increasing promise in accelerating the upgrade and transition of a low-carbon energy portfolio. Finally, stimulating general interest among researchers from diverse disciplines and interactions within the scientific and industrial communities is required to drive the evolution of this exciting and dynamic field.
References
Welsby, D., Price, J., Pye, S. & Ekins, P. Unextractable fossil fuels in a 1.5 °C world. Nature 597, 230–234 (2021).
Zou, C., Zhao, Q., Zhang, G. & Xiong, B. Energy revolution: from a fossil energy era to a new energy era. Nat. Gas. Ind. B 3, 1–11 (2016).
Xu, W. et al. A droplet-based electricity generator with high instantaneous power density. Nature 578, 392–396 (2020).
Zhang, Z. et al. Emerging hydrovoltaic technology. Nat. Nanotechnol. 13, 1109–1119 (2018).
Polman, A., Knight, M., Garnett, E. C., Ehrler, B. & Sinke, W. C. Photovoltaic materials: present efficiencies and future challenges. Science 352, aad4424 (2016).
Benyus, J. M. Biomimicry: Innovation Inspired by Nature (Morrow, 1997).
Stuart-Fox, D. et al. Bio-informed materials: three guiding principles for innovation informed by biology. Nat. Rev. Mater. 8, 565–567 (2023).
Wang, Y., Zhao, W., Han, M., Xu, J. & Tam, K. C. Biomimetic surface engineering for sustainable water harvesting systems. Nat. Water 1, 587–601 (2023).
Feng, S. et al. Three-dimensional capillary ratchet-induced liquid directional steering. Science 373, 1344–1348 (2021).
Vukusic, P. & Sambles, J. R. Photonic structures in biology. Nature 424, 852–855 (2003).
An, S. et al. Biological and bioinspired thermal energy regulation and utilization. Chem. Rev. 123, 7081–7118 (2023).
Luo, D. et al. Autonomous self-burying seed carriers for aerial seeding. Nature 614, 463–470 (2023).
Jung, W., Kim, W. & Kim, H.-Y. Self-burial mechanics of hygroscopically responsive awns. Integr. Comp. Biol. 54, 1034–1042 (2014).
Dawson, C., Vincent, J. F. V. & Rocca, A.-M. How pine cones open. Nature 390, 668 (1997).
Poppinga, S., Correa, D., Bruchmann, B., Menges, A. & Speck, T. Plant movements as concept generators for the development of biomimetic compliant mechanisms. Integr. Comp. Biol. 60, 886–895 (2020).
Webster, J., Davey, R. A., Duller, G. A. & Ingold, C. T. Ballistospore discharge in Itersonilia perplexans. Trans. Br. Mycol. Soc. 82, 13–29 (1984).
Li, J. et al. Directional transport of high-temperature Janus droplets mediated by structural topography. Nat. Phys. 12, 606–612 (2016).
van Leeuwen, J. L. Launched at 36,000g. Science 329, 395–396 (2010).
Whitaker, D. L. & Edwards, J. Sphagnum moss disperses spores with vortex rings. Science 329, 406 (2010).
Noblin, X. et al. The fern sporangium: a unique catapult. Science 335, 1322 (2012).
Ma, M., Guo, L., Anderson, D. G. & Langer, R. Bio-inspired polymer composite actuator and generator driven by water gradients. Science 339, 186–189 (2013).
Chen, X., Mahadevan, L., Driks, A. & Sahin, O. Bacillus spores as building blocks for stimuli-responsive materials and nanogenerators. Nat. Nanotechnol. 9, 137–141 (2014).
Lv, J. et al. Solar utilization beyond photosynthesis. Nat. Rev. Chem. 7, 91–105 (2023).
Scholes, G. D., Fleming, G. R., Olaya-Castro, A. & van Grondelle, R. Lessons from nature about solar light harvesting. Nat. Chem. 3, 763–774 (2011).
Soudi, N., Nanayakkara, S., Jahed, N. M. & Naahidi, S. Rise of nature-inspired solar photovoltaic energy convertors. Sol. Energy 208, 31–45 (2020).
Hünig, R. et al. Flower power: exploiting plants’ epidermal structures for enhanced light harvesting in thin-film solar cells. Adv. Opt. Mater. 4, 1487–1493 (2016).
Proppe, A. H. et al. Bioinspiration in light harvesting and catalysis. Nat. Rev. Mater. 5, 828–846 (2020).
Ren, J. et al. Biological material interfaces as inspiration for mechanical and optical material designs. Chem. Rev. 119, 12279–12336 (2019).
Ishay, J. S., Benshalom-Shimony, T., Ben-Shalom, A. & Kristianpoller, N. Photovoltaic effects in the Oriental hornet, Vespa orientalis. J. Insect Physiol. 38, 37–48 (1992).
Plotkin, M. et al. Solar energy harvesting in the epicuticle of the oriental hornet (Vespa orientalis). Sci. Nat. 97, 1067–1076 (2010).
Catania, K. The shocking predatory strike of the electric eel. Science 346, 1231–1234 (2014).
Schroeder, T. B. H. et al. An electric-eel-inspired soft power source from stacked hydrogels. Nature 552, 214–218 (2017).
Shamos, M. H. & Lavine, L. S. Piezoelectricity as a fundamental property of biological tissues. Nature 213, 267–269 (1967).
Kao, F.-C., Chiu, P.-Y., Tsai, T.-T. & Lin, Z.-H. The application of nanogenerators and piezoelectricity in osteogenesis. Sci. Technol. Adv. Mater. 20, 1103–1117 (2019).
Pfeffer, C. et al. Filamentous bacteria transport electrons over centimetre distances. Nature 491, 218–221 (2012).
Bjerg, J. T. et al. Long-distance electron transport in individual, living cable bacteria. Proc. Natl Acad. Sci. USA 115, 5786–5791 (2018).
Grinter, R. et al. Structural basis for bacterial energy extraction from atmospheric hydrogen. Nature 615, 541–547 (2023).
Liu, M., Wang, S. & Jiang, L. Nature-inspired superwettability systems. Nat. Rev. Mater. 2, 17036 (2017).
Li, J., Li, J., Sun, J., Feng, S. & Wang, Z. Biological and engineered topological droplet rectifiers. Adv. Mater. 31, 1806501 (2019).
Ahamed, M. K., Wang, H. & Hazell, P. J. From biology to biomimicry: using nature to build better structures—a review. Constr. Build. Mater. 320, 126195 (2022).
Xu, W. et al. Triboelectric wetting for continuous droplet transport. Sci. Adv. 8, eade2085 (2022).
Ren, J. et al. Bioinspired energy storage and harvesting devices. Adv. Mater. Technol. 6, 2001301 (2021).
Katiyar, N. K., Goel, G., Hawi, S. & Goel, S. Nature-inspired materials: emerging trends and prospects. NPG Asia Mater. 13, 56 (2021).
Mei, Y. & Tang, C. Y. Recent developments and future perspectives of reverse electrodialysis technology: a review. Desalination 425, 156–174 (2018).
Jiang, D. et al. Water–solid triboelectric nanogenerators: an alternative means for harvesting hydropower. Renew. Sustain. Energy Rev. 115, 109366 (2019).
Wang, X. et al. Hydrovoltaic technology: from mechanism to applications. Chem. Soc. Rev. 51, 4902–4927 (2022).
Xu, W. & Wang, Z. Fusion of slippery interfaces and transistor-inspired architecture for water kinetic energy harvesting. Joule 4, 2527–2531 (2020).
Logan, B. E. & Elimelech, M. Membrane-based processes for sustainable power generation using water. Nature 488, 313–319 (2012).
Turek, M. & Bandura, B. Renewable energy by reverse electrodialysis. Desalination 205, 67–74 (2007).
Veerman, J., Saakes, M., Metz, S. & Harmsen, G. Reverse electrodialysis: performance of a stack with 50 cells on the mixing of sea and river water. J. Membr. Sci. 327, 136–144 (2009).
Kim, D.-K., Duan, C., Chen, Y.-F. & Majumdar, A. Power generation from concentration gradient by reverse electrodialysis in ion-selective nanochannels. Microfluid. Nanofluid. 9, 1215–1224 (2010).
Zhang, Z., Wen, L. & Jiang, L. Nanofluidics for osmotic energy conversion. Nat. Rev. Mater. 6, 622–639 (2021).
Długołęcki, P. et al. On the resistances of membrane, diffusion boundary layer and double layer in ion exchange membrane transport. J. Membr. Sci. 349, 369–379 (2010).
Vermaas, D. A., Kunteng, D., Saakes, M. & Nijmeijer, K. Fouling in reverse electrodialysis under natural conditions. Water Res. 47, 1289–1298 (2013).
Doyle, D. A. et al. The structure of the potassium channel: molecular basis of K+ conduction and selectivity. Science 280, 69–77 (1998).
Siria, A. et al. Giant osmotic energy conversion measured in a single transmembrane boron nitride nanotube. Nature 494, 455–458 (2013).
Gao, J. et al. High-performance ionic diode membrane for salinity gradient power generation. J. Am. Chem. Soc. 136, 12265–12272 (2014).
Daiguji, H. Ion transport in nanofluidic channels. Chem. Soc. Rev. 39, 901–911 (2010).
Guo, W., Tian, Y. & Jiang, L. Asymmetric ion transport through ion-channel-mimetic solid-state nanopores. Acc. Chem. Res. 46, 2834–2846 (2013).
Feng, J. et al. Single-layer MoS2 nanopores as nanopower generators. Nature 536, 197–200 (2016).
Macha, M., Marion, S., Nandigana, V. V. R. & Radenovic, A. 2D materials as an emerging platform for nanopore-based power generation. Nat. Rev. Mater. 4, 588–605 (2019).
Chen, X. et al. Scaling up nanoscale water-driven energy conversion into evaporation-driven engines and generators. Nat. Commun. 6, 7346 (2015).
Yang, J., Lu, F., Kostiuk, L. W. & Kwok, D. Y. Electrokinetic microchannel battery by means of electrokinetic and microfluidic phenomena. J. Micromech. Microeng. 13, 963 (2003).
Xue, G. et al. Water-evaporation-induced electricity with nanostructured carbon materials. Nat. Nanotechnol. 12, 317–321 (2017).
Yang, P. et al. Solar-driven simultaneous steam production and electricity generation from salinity. Energy Environ. Sci. 10, 1923–1927 (2017).
Ding, T. P. et al. All-printed porous carbon film for electricity generation from evaporation-driven water flow. Adv. Funct. Mater. 27, 1700551 (2017).
Hong, S. et al. Nature-inspired, 3D origami solar steam generator toward near full utilization of solar energy. ACS Appl. Mater. Interfaces 10, 28517–28524 (2018).
Wong, S. C. et al. Humidity gradients in the air spaces of leaves. Nat. Plants 8, 971–978 (2022).
Li, J. et al. Surface functional modification boosts the output of an evaporation-driven water flow nanogenerator. Nano Energy 58, 797–802 (2019).
Zhou, X. et al. Harvesting electricity from water evaporation through microchannels of natural wood. ACS Appl. Mater. Interfaces 12, 11232–11239 (2020).
Liu, X. et al. Microbial biofilms for electricity generation from water evaporation and power to wearables. Nat. Commun. 13, 1–8 (2022).
Ye, M., Cheng, H., Gao, J., Li, C. & Qu, L. A respiration-detective graphene oxide/lithium battery. J. Mater. Chem. A 4, 19154–19159 (2016).
Zhao, F., Cheng, H., Zhang, Z., Jiang, L. & Qu, L. Direct power generation from a graphene oxide film under moisture. Adv. Mater. 27, 4351–4357 (2015).
Sun, Z. et al. Nanofiber fabric based ion-gradient-enhanced moist-electric generator with a sustained voltage output of 1.1 volts. Mater. Horiz. 8, 2303–2309 (2021).
Wang, H. et al. Bilayer of polyelectrolyte films for spontaneous power generation in air up to an integrated 1,000 V output. Nat. Nanotechnol. 16, 811–819 (2021).
Lu, W. et al. Anion–cation heterostructured hydrogels for all-weather responsive electricity and water harvesting from atmospheric air. Nano Energy 104, 107892 (2022).
Tan, J. et al. Self-sustained electricity generator driven by the compatible integration of ambient moisture adsorption and evaporation. Nat. Commun. 13, 3643 (2022).
Wang, H. et al. Moisture adsorption–desorption full cycle power generation. Nat. Commun. 13, 2524 (2022).
Liu, X. et al. Power generation from ambient humidity using protein nanowires. Nature 578, 550–554 (2020).
Li, M. et al. Biological nanofibrous generator for electricity harvest from moist air flow. Adv. Funct. Mater. 29, 1901798 (2019).
Lin, S., Wang, Z., Chen, X., Ren, J. & Ling, S. Ultrastrong and highly sensitive fiber microactuators constructed by force‐reeled silks. Adv. Sci. 7, 1902743 (2020).
Yang, L., Zhang, L. & Sun, D. Energy harvesting technology based on moisture-responsive actuators. J. Mater. Chem. A 11, 18530–18560 (2023).
Lin, Z. H., Cheng, G., Lee, S., Pradel, K. C. & Wang, Z. L. Harvesting water drop energy by a sequential contact‐electrification and electrostatic‐induction process. Adv. Mater. 26, 4690–4696 (2014).
Moon, J. K., Jeong, J., Lee, D. & Pak, H. K. Electrical power generation by mechanically modulating electrical double layers. Nat. Commun. 4, 1487 (2013).
Yin, J. et al. Generating electricity by moving a droplet of ionic liquid along graphene. Nat. Nanotechnol. 9, 378–383 (2014).
Zheng, H. et al. Remote‐controlled droplet chains‐based electricity generators. Adv. Energy Mater. 13, 2203825 (2023).
Xu, X. et al. Droplet energy harvesting panel. Energy Environ. Sci. 15, 2916–2926 (2022).
Li, Y. et al. A fully self‐powered cholesteric smart window actuated by droplet‐based electricity generator. Adv. Opt. Mater. 10, 2102274 (2022).
Li, L. et al. Sparking potential over 1200 V by a falling water droplet. Sci. Adv. 9, eadi2993 (2023).
Li, Y. et al. A droplet-based electricity generator incorporating Kelvin water dropper with ultrahigh instantaneous power density. Droplet 3, e91 (2024).
Wang, L. et al. Harvesting energy from high‐frequency impinging water droplets by a droplet‐based electricity generator. EcoMat 3, e12116 (2021).
Ma, Z., Ai, J., Shi, Y., Wang, K. & Su, B. A superhydrophobic droplet‐based magnetoelectric hybrid system to generate electricity and collect water simultaneously. Adv. Mater. 32, 2006839 (2020).
Chen, Y. et al. Interfacial laser‐induced graphene enabling high‐performance liquid−solid triboelectric nanogenerator. Adv. Mater. 33, 2104290 (2021).
Wu, H. et al. Fully biodegradable water droplet energy harvester based on leaves of living plants. ACS Appl. Mater. Interfaces 12, 56060–56067 (2020).
Armiento, S., Filippeschi, C., Meder, F. & Mazzolai, B. Liquid–solid contact electrification when water droplets hit living plant leaves. Commun. Mater. 3, 79 (2022).
Xu, W. et al. SLIPS-TENG: robust triboelectric nanogenerator with optical and charge transparency using a slippery interface. Natl Sci. Rev. 6, 540–550 (2019).
Song, Y. et al. Achieving ultra-stable and superior electricity generation by integrating transistor-like design with lubricant armor. Innovation 3, 100301 (2022).
Lafuma, A. & Quéré, D. Slippery pre-suffused surfaces. Europhys. Lett. 96, 56001 (2011).
Wong, T.-S. et al. Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity. Nature 477, 443–447 (2011).
Yan, X. et al. Bubble energy generator. Sci. Adv. 8, eabo7698 (2022).
Li, C., Liu, X., Yang, D. & Liu, Z. Triboelectric nanogenerator based on a moving bubble in liquid for mechanical energy harvesting and water level monitoring. Nano Energy 95, 106998 (2022).
Ballif, C., Haug, F.-J., Boccard, M., Verlinden, P. J. & Hahn, G. Status and perspectives of crystalline silicon photovoltaics in research and industry. Nat. Rev. Mater. 7, 597–616 (2022).
Li, H. & Zhang, W. Perovskite tandem solar cells: from fundamentals to commercial deployment. Chem. Rev. 120, 9835–9950 (2020).
Zhou, Y., Herz, L. M., Jen, A. K. Y. & Saliba, M. Advances and challenges in understanding the microscopic structure–property–performance relationship in perovskite solar cells. Nat. Energy 7, 794–807 (2022).
Yoon, J. et al. Bio-inspired strategies for next-generation perovskite solar mobile power sources. Chem. Soc. Rev. 50, 12915–12984 (2021).
Sun, J. et al. Biomimetic moth-eye nanofabrication: enhanced antireflection with superior self-cleaning characteristic. Sci. Rep. 8, 5438 (2018).
Siddique, R. H. et al. Bioinspired phase-separated disordered nanostructures for thin photovoltaic absorbers. Sci. Adv. 3, e1700232 (2017).
Choi, J. S., Jang, Y.-W., Kim, U., Choi, M. & Kang, S. M. Optically and mechanically engineered anti-reflective film for highly efficient rigid and flexible perovskite solar cells. Adv. Energy Mater. 12, 2201520 (2022).
Lou, S., Guo, X., Fan, T. & Zhang, D. Butterflies: inspiration for solar cells and sunlight water-splitting catalysts. Energy Environ. Sci. 5, 9195–9216 (2012).
Schmager, R. et al. Texture of the viola flower for light harvesting in photovoltaics. ACS Photonics 4, 2687–2692 (2017).
Zhu, J., Hsu, C.-M., Yu, Z., Fan, S. & Cui, Y. Nanodome solar cells with efficient light management and self-cleaning. Nano Lett. 10, 1979–1984 (2010).
Kang, S. M., Ahn, N., Lee, J.-W., Choi, M. & Park, N.-G. Water-repellent perovskite solar cell. J. Mater. Chem. A 2, 20017–20021 (2014).
Zhang, H. et al. Design of superhydrophobic surfaces for stable perovskite solar cells with reducing lead leakage. Adv. Energy Mater. 11, 2102281 (2021).
Meng, X. et al. A biomimetic self-shield interface for flexible perovskite solar cells with negligible lead leakage. Adv. Funct. Mater. 31, 2106460 (2021).
Zorba, V. et al. Biomimetic artificial surfaces quantitatively reproduce the water repellency of a lotus leaf. Adv. Mater. 20, 4049–4054 (2008).
Ye, C. et al. An integrated solar panel with a triboelectric nanogenerator array for synergistic harvesting of raindrop and solar energy. Adv. Mater. 35, 2209713 (2023).
Liu, Y. et al. Integrating a silicon solar cell with a triboelectric nanogenerator via a mutual electrode for harvesting energy from sunlight and raindrops. ACS Nano 12, 2893–2899 (2018).
Liao, M. et al. An integrated electricity generator harnessing water and solar energy featuring common-electrode configuration. Nano Energy 116, 108831 (2023).
Wang, X. et al. Engineering fluorinated-cation containing inverted perovskite solar cells with an efficiency of >21% and improved stability towards humidity. Nat. Commun. 12, 52 (2021).
Heo, D., Jang, W. & Kim, S. Recent review of interfacial engineering for perovskite solar cells: effect of functional groups on the stability and efficiency. Mater. Today Chem. 26, 101224 (2022).
Liu, Y. et al. Ultrahydrophobic 3D/2D fluoroarene bilayer-based water-resistant perovskite solar cells with efficiencies exceeding 22%. Sci. Adv. 5, eaaw2543 (2019).
Qian, X. et al. Artificial phototropism for omnidirectional tracking and harvesting of light. Nat. Nanotechnol. 14, 1048–1055 (2019).
Lamoureux, A., Lee, K., Shlian, M., Forrest, S. R. & Shtein, M. Dynamic kirigami structures for integrated solar tracking. Nat. Commun. 6, 8092 (2015).
Yu, B. et al. Thermosensitive crystallization-boosted liquid thermocells for low-grade heat harvesting. Science 370, 342–346 (2020).
Lheritier, P. et al. Large harvested energy with non-linear pyroelectric modules. Nature 609, 718–721 (2022).
González-Roubaud, E., Pérez-Osorio, D. & Prieto, C. Review of commercial thermal energy storage in concentrated solar power plants: steam vs. molten salts. Renew. Sust. Energ. Rev. 80, 133–148 (2017).
Kucharski, T. J. et al. Templated assembly of photoswitches significantly increases the energy-storage capacity of solar thermal fuels. Nat. Chem. 6, 441–447 (2014).
Liu, Z. et al. Maximizing the performance of n-type Mg3Bi2 based materials for room-temperature power generation and thermoelectric cooling. Nat. Commun. 13, 1120 (2022).
Liu, Y. et al. Thermo-electrochemical cells for heat to electricity conversion: from mechanisms, materials, strategies to applications. Energy Environ. Sci. 15, 3670–3687 (2022).
Wang, X. et al. Direct thermal charging cell for converting low-grade heat to electricity. Nat. Commun. 10, 4151 (2019).
Shi, X.-L., Zou, J. & Chen, Z.-G. Advanced thermoelectric design: from materials and structures to devices. Chem. Rev. 120, 7399–7515 (2020).
Uchida, K. et al. Observation of the spin seebeck effect. Nature 455, 778–781 (2008).
Flipse, J., Bakker, F. L., Slachter, A., Dejene, F. K. & van Wees, B. J. Direct observation of the spin-dependent Peltier effect. Nat. Nanotechnol. 7, 166–168 (2012).
Kraemer, D. et al. Concentrating solar thermoelectric generators with a peak efficiency of 7.4%. Nat. Energy 1, 1–8 (2016).
Hu, G., Edwards, H. & Lee, M. Silicon integrated circuit thermoelectric generators with a high specific power generation capacity. Nat. Electron. 2, 300–306 (2019).
Zhou, Y. et al. Giant polarization ripple in transverse pyroelectricity. Nat. Commun. 14, 426 (2023).
Yang, M.-M. et al. Piezoelectric and pyroelectric effects induced by interface polar symmetry. Nature 584, 377–381 (2020).
Duan, J. et al. Liquid-state thermocells: opportunities and challenges for low-grade heat harvesting. Joule 5, 768–779 (2021).
Kim, H. et al. Biomimetic chameleon soft robot with artificial crypsis and disruptive coloration skin. Nat. Commun. 12, 4658 (2021).
Wang, Y. et al. In situ photocatalytically enhanced thermogalvanic cells for electricity and hydrogen production. Science 381, 291–296 (2023).
Chen, C. et al. Structural design of nanowire wearable stretchable thermoelectric generator. Nano Lett. 22, 4131–4136 (2022).
Kraemer, D. et al. High-performance flat-panel solar thermoelectric generators with high thermal concentration. Nat. Mater. 10, 532–538 (2011).
Han, C.-G. et al. Giant thermopower of ionic gelatin near room temperature. Science 368, 1091–1098 (2020).
Sun, T., Wang, L. & Jiang, W. Pushing thermoelectric generators toward energy harvesting from the human body: challenges and strategies. Mater. Today 57, 121–145 (2022).
Li, L. et al. Enhancing hydrovoltaic power generation through heat conduction effects. Nat. Commun. 13, 1043 (2022).
Leung, E. M. et al. A dynamic thermoregulatory material inspired by squid skin. Nat. Commun. 10, 1947 (2019).
Li, T. et al. Cellulose ionic conductors with high differential thermal voltage for low-grade heat harvesting. Nat. Mater. 18, 608–613 (2019).
Shi, N. N. et al. Keeping cool: enhanced optical reflection and radiative heat dissipation in Saharan silver ants. Science 349, 298–301 (2015).
Li, T. et al. Thermoelectric properties and performance of flexible reduced graphene oxide films up to 3,000 K. Nat. Energy 3, 148–156 (2018).
Ren, W. et al. High-performance wearable thermoelectric generator with self-healing, recycling, and Lego-like reconfiguring capabilities. Sci. Adv. 7, eabe0586 (2021).
Lee, B. et al. High-performance compliant thermoelectric generators with magnetically self-assembled soft heat conductors for self-powered wearable electronics. Nat. Commun. 11, 5948 (2020).
Zhan, H.-J. et al. Biomimetic carbon tube aerogel enables super-elasticity and thermal insulation. Chem 5, 1871–1882 (2019).
Zhang, Q., Deng, K., Wilkens, L., Reith, H. & Nielsch, K. Micro-thermoelectric devices. Nat. Electron. 5, 333–347 (2022).
Hao, S., Fu, Q., Meng, L., Xu, F. & Yang, J. A biomimetic laminated strategy enabled strain-interference free and durable flexible thermistor electronics. Nat. Commun. 13, 6472 (2022).
Sun, T. et al. Stretchable fabric generates electric power from woven thermoelectric fibers. Nat. Commun. 11, 572 (2020).
Wu, M. et al. Biomimetic, knittable aerogel fiber for thermal insulation textile. Science 382, 1379–1383 (2023).
Jiang, D. et al. A triboelectric and pyroelectric hybrid energy harvester for recovering energy from low-grade waste fluids. Nano Energy 70, 104459 (2020).
Wu, Y. et al. Triboelectric–thermoelectric hybrid nanogenerator for harvesting energy from ambient environments. Adv. Mater. Technol. 3, 1800166 (2018).
Zhou, Y. et al. Non-planar dielectrics derived thermal and electrostatic field inhomogeneity for boosted weather-adaptive energy harvesting. Natl. Sci. Rev. 10, nwad186 (2023).
Park, T. et al. Photothermally activated pyroelectric polymer films for harvesting of solar heat with a hybrid energy cell structure. ACS Nano 9, 11830–11839 (2015).
Sripadmanabhan Indira, S. et al. A review on various configurations of hybrid concentrator photovoltaic and thermoelectric generator system. Sol. Energy 201, 122–148 (2020).
Han, W. B. et al. Zebra-inspired stretchable, biodegradable radiation modulator for all-day sustainable energy harvesters. Sci. Adv. 9, eadf5883 (2023).
Ao, X. et al. Self-adaptive integration of photothermal and radiative cooling for continuous energy harvesting from the sun and outer space. Proc. Natl Acad. Sci. USA 119, e2120557119 (2022).
Zhang, S., Wu, Z., Liu, Z. & Hu, Z. An emerging energy technology: self-uninterrupted electricity power harvesting from the sun and cold space. Adv. Energy Mater. 13, 2300260 (2023).
Ren, H., Xiao, T., Zhang, Q. & Liu, Z. Photosynthesis-inspired bifunctional energy-harvesting devices that convert light and salinity gradients into electricity. Chem. Commun. 54, 12310–12313 (2018).
Wang, Q. et al. Efficient solar-osmotic power generation from bioinspired anti-fouling 2D WS2 composite membranes. Angew. Chem. Int. Ed. Engl. 62, e202302938 (2023).
Wang, Z. L. & Wang, A. C. On the origin of contact-electrification. Mater. Today 30, 34–51 (2019).
Yao, Z. et al. Machine learning for a sustainable energy future. Nat. Rev. Mater. 8, 202–215 (2023).
Portilla, L. et al. Wirelessly powered large-area electronics for the Internet of Things. Nat. Electron. 6, 10–17 (2023).
Lee, G.-H. et al. Multifunctional materials for implantable and wearable photonic healthcare devices. Nat. Rev. Mater. 5, 149–165 (2020).
Acknowledgements
The authors acknowledge financial support from the National Natural Science Foundation of China (T2293694, 51975502), Research Grants Council of Hong Kong (C1006-20W, 11213320, 11219219), Shenzhen Key Project (JCYJ20200109143206663) and Tencent Foundation through the XPLORER PRIZE.
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Zhang, B., Xu, W., Peng, L. et al. Nature-inspired interfacial engineering for energy harvesting. Nat Rev Electr Eng 1, 218–233 (2024). https://doi.org/10.1038/s44287-024-00029-6
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DOI: https://doi.org/10.1038/s44287-024-00029-6