Review
Two-dimensional MXene-based and MXene-derived photocatalysts: Recent developments and perspectives

https://doi.org/10.1016/j.cej.2020.128099Get rights and content

Highlights

  • Synthesis methods of MXene-based and MXene‑derived photocatalysts was summarized.

  • The role of MXene in the photocatalytic application was discussed.

  • Challenges and perspectives for future research on MXenes were outlined.

Abstract

Since their discovery in 2011, 2D MXenes have gained tremendous traction for their flexible elemental composition, unique 2D-layered structure, large surface area, abundant surface terminations, and excellent photoelectronic properties. In particular, the latest advances demonstrate that MXene-based and MXene-derived photocatalysts are the most advantageous and novel materials in the photocatalytic field. In this review, we summarize recent studies on the preparation of MXene-based and MXene-derived photocatalysts, including mechanical/ultrasonic mixing, electrostatic self-assembly, hydrothermal/solvothermal preparations, and calcination approaches. In addition, we present a comprehensive review of the environmental and energy applications of MXene-based and MXene-derived photocatalysts, including organic pollutant degradation, water splitting for H2 evolution, CO2 reduction, nitrogen fixation, H2O2 production, antibacterial application, desulfurization and denitrogenation of fuels. The roles of MXene as a co-catalyst or precursor in photocatalytic applications are addressed herein. Finally, the lingering challenges and perspectives on the study of MXenes in the future are presented.

Introduction

Two-dimensional (2D) materials have drawn immense attention since the discovery of monolayer graphene in 2004 [1]. To date, many types of 2D materials also exhibit excellent catalytic, electronic, and optoelectronic properties [2], [3], [4], [5], [6], such as transition metal dichalcogenides (e.g., MoS2 [7], WS2 [8]), g-C3N4 [9], [10], layered double hydroxides (LDHs) [11], [12], and black phosphorous [13], [14]. Moreover, the 2D structure also minimizes the migration distances between charge carriers and the reaction interface, inhibiting the possibility of charge carrier recombination, which improves the photocatalytic performance [15]. In recent years, MXenes have become one of the most popular 2D materials owing to their diverse elemental compositions, unique 2D structure, large surface area, abundant surface terminations, and excellent photoelectronic properties [16], [17], [18], [19], [20], [21], [22], [23], [24], [25], [26]. Generally, Mn+1AXn (n = 1–3) precursors are usually etched to prepare Mn+1XnTx (MXenes, Fig. 1), where M represents a transition metal (e.g., Ti, Nb, Ta, and Mo), A represents group 13 and 14 elements from the periodic table (e.g., Si, Ga, and Al), X stands for C and/or N elements, and Tx is –O, –F, –OH, etc. [27], [28], [29], [30], [31], [32], [33] Experimentally, the composition and surface properties of MXenes vary with different etching methods [34], [35], [36]. Since the first report of the Ti3C2 MXene in 2011 [37], >20 kinds of MXenes have been successfully obtained, such as Ti3C2, Ti3CN, TiNbC, V2C, Mo2C, Nb2C and Y2CF2 [38], [39], [40], [41].

The most widely used methods for the synthesis of MXenes are direct HF etching and indirect in situ HF etching (e.g., using a mixture of HCl and LiF). To enhance the yield of MXenes, delamination with various organic intercalants (e.g., dimethyl sulfoxide, isopropylamine, tetramethylammonium hydroxide), high-temperature etching, and chemical vapor deposition have also been explored [42], [43], [44]. The timeline of MXenes prepared by various etching methods is presented in Fig. 2 [44]. Until now, MXenes have been used for various applications, such as absorbents, supercapacitors, gas sensors, and electrocatalysts. Apart from those applications, MXenes have become highly desirable materials in recent years as co-catalysts or precursors for photocatalytic environmental remediation and energy conversion.

A literature investigation revealed that a small number of reviews have summarized the progress in the preparation and applications of MXenes, and only a few of them refer to MXene-based and MXene-derived photocatalysts in photocatalytic environmental remediation and artificial photosynthesis. The significant difference of these two types of photocatalysts is that a certain component in the latter is from the oxidization of MXene precursor. Importantly, research on MXenes for photocatalysis is progressing rapidly. In this review, we summarize the latest progress on the preparation and applications of 2D MXene-based and MXene-derived photocatalysts in the photocatalytic field. First, we introduce the synthesis process of MXene-based and MXene-derived photocatalysts in detail. Then, we present a systematic review of recent studies addressing the environment and energy applications of MXene-based and MXene-derived photocatalysts, including organic pollutant degradation, water splitting for H2 evolution, CO2 reduction, nitrogen fixation, hydrogen peroxide (H2O2) production, antibacterial application, desulfurization and denitrogenation in fuels. Finally, a prospective outlook for future research is proposed from the current research challenges at the forefront of environmental and energy science.

Section snippets

Preparation of MXene-based photocatalysts

For the past few years, the construction of composites has been an effective way to synthesize highly efficient photocatalysts. Owing to their unique characteristics, MXenes have been regarded as promising research objects for the preparation of photocatalysts. The most widely used methods for the synthesis of MXene-based and MXene-derived photocatalysts include mechanical/ultrasonic mixing, electrostatic self-assembly, hydrothermal/solvothermal treatment, and calcination processes.

Preparation of MXene-derived photocatalysts

Calcination and hydrothermal oxidation strategies are most widely adopted for the preparation of MXene-derived photocatalysts by the in-situ oxidation of the MXene precursors. In recent decades, TiO2 has been the most-investigated semiconductor photocatalyst owing to its environmental friendliness, low cost, redox potential, and outstanding photostability. However, individual TiO2 still has two disadvantages that are difficult to overcome: a wide band gap and a high photogenerated carrier

Water and air purification

With the rapid improvements of modern industrialization, organic pollutants in water have dramatically increased, causing enormous harm to human health and the natural environment. Various methods, including adsorption, biotreatment, peroxymonosulfate activation, Fenton oxidation, and photocatalytic degradation have been widely used for water treatment [79], [80], [81], [82], [83], [84], [85], [86], [87], [88], [89], [90], [91], [92], [93], [94]. Among these methods, photocatalysis is a

Facilitating charge separation and transfer

How to improve the separation efficiency of photogenerated charge carriers have been a research hotspot in the photocatalytic field. Generally, MXene as a co-catalyst could restrict the recombination of photogenerated electrons and hole in the photocatalytic system [176], [177], [178], [179]. Experimentally, the Schottky junction could be formed between the semiconductor photocatalysts and Ti3C2. For instance, Ran et al. [180] found that electrons could transfer from CdS to Ti3C2 in the CdS/Ti3C

Conclusions and outlook

In summary, research on MXene has bloomed since the first work appeared in 2011. Among the MXene family, Ti3C2 is the most studied in the photocatalytic field. As stated in this review paper, a variety of synthesis methods including mechanical/ultrasonic mixing, electrostatic self-assembly, hydrothermal/solvothermal methods, and calcination approaches have been adopted for fabricating MXene-based and MXene-derived photocatalysts. Benefiting from the flexible adjustability of the elemental

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgement

This work was supported by the National Natural Science Foundation of China (NSFC No. 51472194) and the Natural Science Foundation of Hubei Province (2016CFA078).

References (197)

  • M. Khazaei et al.

    Recent advances in MXenes: From fundamentals to applications

    Current Opinion in Solid State and Materials Science

    (2019)
  • C. Peng et al.

    A hydrothermal etching route to synthesis of 2D MXene (Ti3C2, Nb2C): enhanced exfoliation and improved adsorption performance

    Ceram. Int.

    (2018)
  • J.Y. Li et al.

    Visible-light-driven integrated organic synthesis and hydrogen evolution over 1D/2D CdS-Ti3C2Tx MXene composites

    Appl. Catal. B Environ.

    (2020)
  • Y. Yang et al.

    Ti3C2 Mxene/porous g-C3N4 interfacial Schottky junction for boosting spatial charge separation in photocatalytic H2O2 production

    Appl. Catal. B Environ.

    (2019)
  • Y. Cao et al.

    Fabrication of novel CuFe2O4/MXene hierarchical heterostructures for enhanced photocatalytic degradation of sulfonamides under visible light

    J. Hazard. Mater.

    (2020)
  • J. Zhang et al.

    MoS2/Ti3C2 heterostructure for efficient visible-light photocatalytic hydrogen generation

    Int. J. Hydrogen Energy

    (2020)
  • L.K. Zhang et al.

    Boosting visible-light-driven photocatalytic activity of BiPO4 via constructing schottky junction with Ti3C2 MXene

    Mater. Design

    (2020)
  • W. Chen et al.

    Ultrathin Co-Co LDHs nanosheets assembled vertically on MXene: 3D nanoarrays for boosted visible-light-driven CO2 reduction

    Chem. Eng. J.

    (2020)
  • C. Cui et al.

    Bi2WO6/Nb2CTx MXene hybrid nanosheets with enhanced visible-light-driven photocatalytic activity for organic pollutants degradation

    Appl. Surf. Sci.

    (2020)
  • Y. Li et al.

    Z-scheme g-C3N4@CsxWO3 heterostructure as smart window coating for UV isolating, Vis penetrating, NIR shielding and full spectrum photocatalytic decomposing VOCs

    Appl. Catal. B Environ.

    (2018)
  • C. Yang et al.

    2D/2D Ti3C2 MXene/g-C3N4 nanosheets heterojunction for high efficient CO2 reduction photocatalyst: dual effects of urea

    Appl. Catal. B Environ.

    (2020)
  • X. Yi et al.

    Embedding few-layer Ti3C2Tx into alkalized g-C3N4 nanosheets for efficient photocatalytic degradation

    J. Colloid Interface Sci.

    (2020)
  • J.M. Li et al.

    In situ fabrication of 2D/3D g-C3N4/Ti3C2 (MXene) heterojunction for efficient visible-light photocatalytic hydrogen evolution

    Appl. Surf. Sci.

    (2020)
  • J. Low et al.

    Surface modification and enhanced photocatalytic CO2 reduction performance of TiO2: a review

    Appl. Surface Sci.

    (2017)
  • R. Katal et al.

    A review on the synthesis of the various types of anatase TiO2 facets and their applications for photocatalysis

    Chem. Eng. J.

    (2020)
  • H.S. Huang et al.

    One-step in-situ preparation of N-doped TiO2@C derived from Ti3C2 MXene for enhanced visible-light driven photodegradation

    Appl. Catal. B Environ.

    (2019)
  • X.L. Kong et al.

    Orderly layer-by-layered TiO2/carbon superstructures based on MXene’s defect engineeringfor efficient hydrogen evolution

    Appl. Catal. A Gen.

    (2020)
  • Z.B. Wu et al.

    MXene Ti3C2 derived Z-scheme photocatalyst of graphene layers anchored TiO2/g-C3N4 for visible light photocatalytic degradation of refractory organic pollutants

    Chem. Eng. J.

    (2020)
  • Y. Li et al.

    Ti3C2 MXene-derived Ti3C2/TiO2 nanoflowers for noble-metal-free photocatalytic overall water splitting

    Appl. Mater. Today

    (2018)
  • Y.J. Li et al.

    2D/2D/2D heterojunction of Ti3C2 MXene/MoS2 nanosheets/TiO2 nanosheets with exposed (001) facets toward enhanced photocatalytic hydrogen production activity

    Appl. Catal. B Environ.

    (2019)
  • Y.J. Li et al.

    Synergetic effect of defects rich MoS2 and Ti3C2 MXene as cocatalysts for enhanced photocatalytic H2 production activity of TiO2

    Chem. Eng. J.

    (2020)
  • Y.J. Li et al.

    Photocatalytic H2 evolution on TiO2 assembled with Ti3C2 MXene and metallic 1T-WS2 as co-catalysts

    Nano-Micro Lett.

    (2020)
  • J. Li et al.

    Enhanced photocatalytic performance of TiO2@C nanosheets derived from two-dimensional Ti2CTx

    Ceram. Int.

    (2018)
  • X.Y. Wu et al.

    A mechanistic study of amorphous CoSx cages as advanced oxidation catalysts for excellent peroxymonosulfate activation towards antibiotics degradation

    Chem. Eng. J.

    (2020)
  • Y.B. Xiang et al.

    Magnetic yolk-shell structure of ZnFe2O4 nanoparticles for enhanced visible light photo-Fenton degradation towards antibiotics and mechanism study

    Appl. Surf. Sci.

    (2020)
  • Sheng Guo et al.

    Enhanced photocatalytic degradation of organic contaminants over CaFe2O4 under visible LED light irradiation mediated by peroxymonosulfate

    J. Mater. Sci. Technol.

    (2021)
  • S. Guo et al.

    Simultaneous reduction of Cr(VI) and degradation of tetracycline hydrochloride by a novel iron-modified rectorite composite through heterogeneous photo-Fenton processes

    Chem. Eng. J.

    (2020)
  • T. Guo et al.

    A novel α-Fe2O3@g-C3N4 catalyst: Synthesis derived from Fe-based MOF and its superior photo-Fenton performance

    Appl. Surf. Sci.

    (2019)
  • Haijun Huang et al.

    Preparation of cubic Cu2O nanoparticles wrapped by reduced graphene oxide for the efficient removal of rhodamine B

    J. Alloys Compd.

    (2017)
  • Z.Z. Wang et al.

    Novel BiSbO4/BiOBr nanoarchitecture with enhanced visible-light driven photocatalytic performance: oxygen-induced pathway of activation and mechanism unveiling

    Appl. Surf. Sci.

    (2019)
  • H.H. Naing et al.

    Sepiolite supported BiVO4 nanocomposites for efficient photocatalytic degradation of organic pollutants: insight into the interface effect towards Separation of photogenerated charges

    Sci. Total Environ.

    (2020)
  • X. Hu et al.

    Mechanisms underlying the photocatalytic degradation pathway of ciprofloxacin with heterogeneous TiO2

    Chem. Eng. J.

    (2020)
  • S. Li et al.

    Fabrication of highly active Z-scheme Ag/g-C3N4-Ag-Ag3PO4 (110) photocatalyst photocatalyst for visible light photocatalytic degradation of levofloxacin with simultaneous hydrogen production

    Chem. Eng. J.

    (2020)
  • J. Gong et al.

    Metal-free polymeric (SCN)n photocatalyst with adjustable bandgap for efficient organic pollutants degradation and Cr(VI) reduction under visible-light irradiation

    Chem. Eng. J.

    (2020)
  • I. Ihsanullah

    MXenes (two-dimensional metal carbides) as emerging nanomaterials for water purification: Progress, challenges and prospects

    Chem. Eng. J.

    (2020)
  • Yuxin Liu et al.

    Sandwich-like Co3O4/MXene composite with enhanced catalytic performance for Bisphenol A degradation

    Chem. Eng. J.

    (2018)
  • Q.S. Huang et al.

    Simultaneous removal of heavy metal ions and organic pollutant by BiOBr/Ti3C2 nanocomposite

    J. Photochem. Photobiol. A Chem.

    (2019)
  • H.J. Fang et al.

    Facile synthesis of ternary Ti3C2-OH/ln2S3/CdS composite with efficient adsorption and photocatalytic performance towards organic dyes

    J. Solid State Chem.

    (2019)
  • K.S. Novoselov et al.

    Electric field effect in atomically thin carbon films

    Science

    (2004)
  • H. Zhang

    Ultrathin two-dimensional nanomaterials

    ACS Nano

    (2015)
  • Cited by (244)

    View all citing articles on Scopus
    View full text