Facile synthesis of GO@SnO2/TiO2 nanofibers and their behavior in photovoltaics

doi:10.1016/j.jcis.2016.11.041

Journal of Colloid and Interface Science

Volume 490, 15 March 2017, Pages 303-313

https://doi.org/10.1016/j.jcis.2016.11.041 Get rights and content

Abstract

Chemical doping is a widely-used strategy to improve the performance of TiO₂ for the dye-sensitized solar cells (DSCs). However, the effect of two efficient dopants has been rarely investigated. We present the synthesis of GO@SnO₂/TiO₂ nanofibers (NFs) by a facile method using electrospinning and hydrothermal processes. The synthesized NFs are described in terms of morphology, crystallinity and chemistry through FESEM, TEM, HR-TEM, XRD, EDX, XPS, FT-IR and Raman spectra. As the results, the axial ratio and the average diameter of NFs decreased after the hydrothermal treatment and calcination process, respectively. The prepared Titania-based nanofibers have 81.82% anatase and 18.18% rutile-structure. The developed materials are applied as working electrodes of DSCs. The photovoltaic performances showed that the efficiency of the device employed GO@SnO₂/TiO₂ photoanode gave 5.41%, which was higher than those of cells fabricated with SnO₂/TiO₂ NFs (3.41%) and GO@TiO₂ NFs (4.52%) photoanodes. The photovoltaic parameters such as J_sc, V_oc, FF and R_ct are calculated and found to be 11.19 mA cm⁻², 0.72 V, 0.67 and 9.26 Ω, respectively. The high photovoltaic response of DSC based of GO@SnO₂/TiO₂ NFs may be attributed to the large surface area of the NFs, and the low electron recombination. Furthermore, the start-stop switches of the cell devices with the developed photoanode affirmed the stability and photovoltaic performance of the cell.

Graphical abstract

Introduction

Photovoltaic (PV) devices can be one of the acceptable solution of the energy problems which concentrated in increasing energy demand and decreasing the non-renewable resources. Based on first and second generation of solar cells, dye-sensitized solar cells (DSCs) have a high potential due to a low production cost, simple design, flexibility, high feedstock and outperforms competitors for indoor uses [1]. Generally, DSC has photoanode and counter electrode. These two electrodes are separated by electrolyte containing redox species such as I₃⁻/I⁻, and Co^(II)−/Co^(III)−. The photoanode is generally fabricated by absorption of a photosensitizer (dye molecules) on the surface of the substrate which can be TiO₂ or another semiconductor material such as ZnO [2], and SnO₂ [3]. Undoubtedly, the counter electrode of the DSC is the electro-catalyst for reduction of the oxidized form of the electrolyte-redox. Until now, the best counter electrode is Pt because of its high electrocatalytic activity and excellent electrical conductivity [4]. However, Pt is an expensive metal and so, not favored for the worldwide commercialization of DSCs. Hence, it needs to be replaced with non-precious materials such as carbon nanostructures [5], [6].

The electrons source of DSC is the dye molecules through the photon absorption to excite the electron from HOMO state to the LUMO state of the dye. The excited electron may go direct to the conduction band of the semiconductor or back to the electrolyte, which of course is not preferred in the DSC. After that, the electrons pass through the external circuit to the counter electrode, which can connect the circuit through electro reduction of the oxidized form of the electrolyte. Finally, the reduced form of the electrolyte neutralizes the dye molecules to generate fresh dye molecules [7]. Fast charge recombination is a big challenge facing the DSC, it distinctly reduces the electron transfer. This recombination may be happen by three ways [1]. The first one is the electron on the LUMO state with the hole in HOMO state. The second way is the electron on the conduction band of the oxide with the oxidized dye. Finally, the third one is the electron on the conduction band of the oxide with the oxidized form of the electrolyte. Many reports have focused on decreasing the charge recombination and enhancing the electron injection through structure modification and/or improving the dye loading and the electrical properties of the photoanode substrate, which is the target of this study.

It is well known that SnO₂ has a high electrical conductivity and distinguished optical transparency in the visible range of the solar spectrum with band gap of 3.6 eV. Thus, it is expected that the device based on SnO₂ photoanode can give high efficiency compared to TiO₂. In additional, SnO₂ has a low activity toward dye degradation in the region of UV compared to other oxides [8]. Paradoxically, from the practical point of view, the power conversion efficiency of cell employed SnO₂ as a working electrode is lower than that of the device based on TiO₂ working electrode. This may be attributed to two reasons. The first one is the isoelectric point that is lower than that of TiO₂. The second reason is the lower conduction band of the SnO₂ in comparison with TiO₂ which may lead to high overpotential at the dye/oxide interface [9], [10]. From this view, the combination between SnO₂ and TiO₂ has a potential as an efficient photoanode of DSCs [11], [12], [13], [14]. It is known that GO possesses high conductivity and charge-carrier mobility (200,000 cm² V⁻¹ s⁻¹), which can improve the electron transfer from LUMO state of the dye to external circuit [15], [16]. Therefore, it was reported that doping TiO₂ by graphene oxide (GO) can also enhance the performance [17], [18], [19]. Moreover, the structure can contribute in performance enhancement. For instance, SnO₂ @ TiO₂ nanofibers (NFs) photoanode showed a good PV performance [20].

Hence, for the first time, we investigate the doping of GO on the TiO₂/SnO₂ nanocomposite fibers to fabricate a novel and effective photoanode for DSCs. Briefly, this study explains the synthesis of graphene oxide (GO)@SnO₂/TiO₂ NFs by combination between electrospinning and hydrothermal methods to be exploited as a substrate for photoanode DSC. The crystallinity, morphology and chemistry of the prepared material were studied neatly through FESEM, XRD, FT-IR, Raman spectra and EDX studies. Moreover, the introduced nanofibers reveal distinct performance as a photoanode in the DSC.

Section snippets

Materials

Titanium (IV) isopropoxide (>97%, Sigma-Aldrich), N,N-dimethylformamide (DMF, 99.5%, Sigma-Aldrich), tin (II) chloride (98%, Sigma-Aldrich), poly(vinyl acetate) (PVAc, M.wt = 500,000 g/mol), and glacial acetic acid (Sigma-Aldrich) were used without purification. Hexachloroplatinate (IV) and isopropanol were also purchased from Sigma-Aldrich. FTO glass obtained from Pilkington, USA (∼8 Ω/cm). FTO glass was utilized after cleaning by acetone (Fluka). The photosensitizer dye (ruthenium 535 bis-TBA)

Morphology, crystallinity and chemistry of the prepared NFs

Basically, it is well known that FESEM is an acceptable tool to study the morphology of novel nanomaterials. Hence, to get information about the morphology of prepared materials, we conducted FESEM measurements. The results are presented in Fig. 2. Fig. 2A shows the morphology of the fiber mat before calcination. As it can be observed, the produced fiber mat showed dense and smooth surface nanofiber with an average diameter of 292.3 nm and several micrometers in length. There was no change in

Conclusion

Calcination of electrospun nanofiber mats composed of titanium isopropoxide, tin chloride and poly(vinyl acetate) leads to produce good morphology, smooth surface and long axial ratio SnO₂-incoporated TiO₂ nanofibers. Doping of the prepared metal oxides nanofibers can be carried out by hydrothermal treatment in presence of GO aqueous slurry. SnO₂ incorporation and GO doping strongly enhance the performance of the introduced TiO₂-based nanofibers as a photoanode in the DSCs. Typically, the

Acknowledgements

This work was financially supported by National Research Foundation of Korea (NRF) Grant by the Korean Government (MOE) (No. 2014R1A1A2058967). V.-D. Dao and H.-S. Choi acknowledgement support from the Korea Research Fellowship Program fund by the Ministry of Science, ICT and Future Planning through the National Research Foundation of Korea (2015H1D3A1061830). The authors extend their appreciation to International Scientific Partnership Program ISPP at King Saud University for funding this

References (42)

I.M. Mohamed et al.
Synthesis, characterization and performance as a counter electrode for dye-sensitized solar cells of CoCr-decorated carbon nanofibers
Ceram. Int.
(2016)
M. Grätzel
Dye-sensitized solar cells
J. Photochem. Photobiol., C
(2003)
Q. Wali et al.
Tin oxide as a photoanode for dye-sensitised solar cells: current progress and future challenges
J. Power Sources
(2015)
M. Motlak et al.
High-efficiency dye-sensitized solar cells based on nitrogen and graphene oxide co-incorporated TiO₂ nanofibers photoelectrode
Chem. Eng. J.
(2015)
M. Motlak et al.
Influence of GO incorporation in TiO₂ nanofibers on the electrode efficiency in dye-sensitized solar cells
Ceram. Int.
(2015)
I.M. Mohamed et al.
Synthesis of novel SnO₂@TiO₂ nanofibers as an efficient photoanode of dye-sensitized solar cells
Int. J. Hydrogen Energy
(2016)
N.A. Barakat et al.
CoxNiy-decorated graphene as novel, stable and super effective non-precious electro-catalyst for methanol oxidation
Appl. Catal., B
(2014)
V.-D. Dao et al.
An optimum morphology of platinum nanoparticles with excellent electrocatalytic activity for a highly efficient dye-sensitized solar cell
Electrochim. Acta
(2013)
Y. Su et al.
Exceptional negative thermal expansion and viscoelastic properties of graphene oxide paper
Carbon
(2012)
W. Nuansing et al.
Structural characterization and morphology of electrospun TiO₂ nanofibers
Mater. Sci. Eng., B
(2006)

I.M. Mohamed et al.

Efficiency enhancement of dye-sensitized solar cells by use of ZrO₂-doped TiO₂ nanofibers photoanode

J. Colloid Interface Sci.

(2016)

I.M. Mohamed et al.

Nitrogen-doped & SnO₂-incoportaed TiO₂ nanofibers as novel and effective photoanode for enhanced efficiency dye-sensitized solar cells

Chem. Eng. J.

(2016)

Y. Huo et al.

Highly active TiO₂− x− yNxFy visible photocatalyst prepared under supercritical conditions in NH4F/EtOH fluid

Appl. Catal., B

(2009)

M. Motlak et al.

High-efficiency electrode based on nitrogen-doped TiO₂ nanofibers for dye-sensitized solar cells

Electrochim. Acta

(2014)

F. Li et al.

Efficiency enhancement of ZnO-based dye-sensitized solar cell by hollow TiO₂ nanofibers

J. Alloys Compd.

(2014)

P. Du et al.

Dye-sensitized solar cells based on anatase TiO₂/multi-walled carbon nanotubes composite nanofibers photoanode

Electrochim. Acta

(2013)

A. Hagfeldt et al.

Dye-sensitized solar cells

Chem. Rev.

(2010)

S.H. Ko et al.

Nanoforest of hydrothermally grown hierarchical ZnO nanowires for a high efficiency dye-sensitized solar cell

Nano Letters

(2011)

E. Ramasamy et al.

Ordered mesoporous SnO₂− based photoanodes for high-performance dye-sensitized solar cells

J. Phys. Chem. C

(2010)

G. Calogero et al.

A new type of transparent and low cost counter-electrode based on platinum nanoparticles for dye-sensitized solar cells

Energy Environ. Sci.

(2011)

S. Thomas et al.

A review on counter electrode materials in dye-sensitized solar cells

J. Mater. Chem. A

(2014)

Cited by (22)

A flexible plane-wire MoO<inf>2</inf>-anchored carbon nanofiber matrix as freestanding anodes for lithium storage with enhanced cyclability
2024, Materials Research Bulletin
Inspired by beds of silkworm cocoon, a flexible ″plane-wire″ MoO₂-anchored carbon nanofiber matrix has been successfully prepared through electrospinning and subsequent annealing processes. It delivers an initial discharge capacity of 877 mAh g⁻¹ at 200 mA g⁻¹ with a high initial coulombic efficiency of 84.7 % and showcases a high reversible specific capacity of 743 mAh g⁻¹ in the second cycle when employed as free-standing anodes for lithium batteries. It also exhibits good rate performance and superb cyclability, which delivering a specific capacity of 364 mAh g⁻¹ at a high current density of 2 A g⁻¹ and maintains a notable specific capacity of 674 mAh g⁻¹ even after 2000 cycles. It is found that, the carbon nanofiber matrix serves as a robust electronic conductive network to reduce the charge transfer resistance and promote the transportation of Li⁺, and provides excellent support to buffer volume changes of the MoO₂, resulting in enhanced rate performance and cyclability. Moreover, these electrodes are designed to be free-standing, which can improve the flexibility of the electrode and initial coulombic efficiency. It is believed that the as-prepared ″plane-wire″ MoO₂-anchored carbon nanofiber matrix is a promising anode material for high-performance LIBs.
Immobilization of natural extract from Humulus lupulus L. in electrospun polyvinyl alcohol nanofibrous membrane for colorimetric determination of ferric
2024, Journal of Molecular Liquids
Metallochromic nanofibrous membranes were electrospun from an aqueous solution of xanthohumol (XNS) of Humulus lupulus L. (common hop) extract and polyvinyl alcohol (PVA) for determination of ferric ions. In order to detect ferric ions in aquatic media, a simple, portable, quick, and colorimetric detector was prepared using xanthohumol chromophore as an active spectroscopic detection site encapsulated in PVA nanofibers as a hosting bulk. The CIE Lab color parameters show that binding these poisonous ferric cations to the xanthohumol active detection sites results in a noticeable color shift from yellow (467 nm) to off-white (337 nm). This could be attributed to the creation of a coordination bonds between Fe(III) and phenolic xanthohumol. Increasing the quantity of ferric ions was shown to have a linear effect on the monitored color. The xanthohumol extraction was investigated by High Performance Liquid Chromatography (HPLC). Energy-dispersive X-ray spectrometer (EDX) and scanning electron microscopy (SEM) were employed to characterize the surface morphologies and structural properties of XNS@PVA nanofibers. Electrospun XNS@PVA nanofibrous film with a nanofiber diameter of 75–225 nm was produced. In order to prepare water-insoluble nanofibers, they were exposed to cross-linking with glutaraldehyde fumes. The xanthohumol-containing nanofibers exhibit remarkable ease of use with a detection limit of 0.1–300 ppm. XNS@PVA exhibited high selectivity when compared to various transition metal ions, such as K⁺, Na⁺, Ba²⁺, Zn²⁺, Cd²⁺, Hg²⁺, Co²⁺, Mn²⁺, Cu²⁺, Mg²⁺, Ni²⁺, Ca²⁺, Al³⁺, and Cr³⁺. The optimized pH conditions for the detection of Fe(III) were shown to exist between the values of 5 and 7.75. When compared to alternative detection methods, the current assay has the advantages of rapidity, simplicity, cheapness, environmental safety, and ease of operation.
A template-assisted method for synthesizing TiO<inf>2</inf> nanoparticles and Ni/TiO<inf>2</inf> nanocomposites for urea electrooxidation
2024, Materials Chemistry and Physics
The exploration of electrocatalytic urea-assisted wastewater treatment as a method for sustainable energy generation presents a compelling approach within the domain of green chemistry. In this context, titanium dioxide (TiO₂) and nickel-doped TiO₂ (Ni@TiO₂) nanocomposites were developed through an innovative organic template-assisted synthesis strategy. These were denoted as m-TiO₂-org and Ni@m-TiO₂-org, respectively, to create cost-effective and high-performance electrodes for urea electrooxidation in urea-based fuel cells. The structural and chemical properties of the fabricated m-TiO₂-org and Ni@m-TiO₂-org materials were meticulously analyzed using a suite of physicochemical characterization techniques, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA), and Energy-Dispersive X-ray Spectroscopy (EDX). These investigations revealed that both m-TiO₂-org and Ni@m-TiO₂-org materials predominantly consisted of irregular monolithic microparticles formed through the aggregation of spherical nanoparticles, with diameters ranging from 8.16 nm to 13.1 nm. Subsequent evaluations of these TiO₂-based materials as electrocatalysts for urea electrooxidation demonstrated their efficacy, as evidenced by voltammetric and electrochemical impedance spectroscopy measurements. Notably, the Ni@m-TiO₂-org variant exhibited enhanced electrochemical performance, attributed to the presence of Ni²⁺ sites. These sites facilitated electrochemical activation and the formation of active NiOOH sites, leading to a significant increase in the current density (0.78 mA/cm² at 1.523 V vs. the Reversible Hydrogen Electrode (RHE)), as a fiftyfold enhancement compared to m-TiO₂-org@Glassy Carbon Electrode (GCE) under similar conditions (3 M KOH containing 3 M urea), with a Tafel slope of 33 mV/decade. This research not only elucidates the potential of TiO₂-based nanocomposites in the electrooxidation of urea but also heralds the development of innovative electrode materials for commercial electrochemical cells, marking a significant advancement in the field of electrocatalysis and sustainable energy technology.
A brief overview of electrode materials for hydrazine sensors and dye-sensitized solar cells
2023, Microchemical Journal
Environmental pollution and energy crises are receiving considerable global attention. For instance, hydrazine, a toxic compound that can affect human health and the environment, is extensively used in various industries and could be responsible for several diseases. Therefore, accurate determination of hydrazine is critical. Although various strategies have been adopted for hydrazine determination, electrochemical approaches have shown considerable promise in this regard. With respect to mitigating energy crises, solar energy is the most efficient renewable energy source that can be sufficiently converted into electrical energy using photovoltaic devices (solar cells). Dye-sensitized solar cells (DSSCs) have attracted significant attention because of their cost-effectiveness, high performance, and simple fabrication, and can be considered an alternative to conventional solar cells. Extensive efforts have been made to develop high-performance DSSCs. In particular, the performance of DSSCs is significantly influenced by the photoanode material. Recent advances in the electrode materials used for hydrazine sensors and DSSCs, such as TiO₂, ZnO, SnO₂, metal-doped semiconductors, and hybrid composites, are reviewed in this article. The basic principles and operating mechanisms of DSSCs are discussed, along with the inherent challenges and future perspectives.
Fabrication of electrospun nickel sulphide nanoparticles onto carbon nanofibers for efficient urea electro-oxidation in alkaline medium
2021, International Journal of Hydrogen Energy
Citation Excerpt :
Electrospinning method was proposed to fabricate large axial ratio nanofibers [37,38] by subjecting a polymeric solution to a high voltage value. These formed electrospun fibers can be widely utilized for many purposes such as water desalination [39,40], electrocatalysis [41], energy demands [37,42] and medical engineering [43]. Abdelkareem et al. [19] have exploited the electrospinning technique to prepare Ni–Cd carbon nanofibers by applying a voltage value of 20 kV onto a mixed solution of nickel and cadmium acetates in presence of 10 wt% of poly (vinyl alcohol) followed by a calcination step at 850 °C in an inert atmosphere for 2 h. Alajami et al. [44] have stated that NiMn species supported onto carbon nanofibers displayed different activities towards urea electro-oxidation reaction based on the added weight of manganese acetate and the calcination temperature.
To design and synthesize a noble-metal free electrocatalyst with increased efficiency and stability during urea electro-oxidation in alkaline solution is still an important challenge in the electrocatalytic field. In this work, carbon nanofibers were decorated with nickel sulphide nanoparticles [NiS@CNFs] through the electrospinning technique with subsequent heating into an argon atmosphere at 900 °C for 2 h. This formed nanomaterial was extensively characterized through X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Raman spectroscopy and N₂ adsorption-desorption measurements. A conductive network of intertwined CNFs was clearly detected by FE-SEM analysis technique with varied diameters in the range of 0.6–1 μm. A highly porous nature could be suggested after incorporating NiS nanospecies resulting in increased specific surface area and valuable electrocatalytic activity for urea molecules electro-oxidation. The pore size distribution curves showed a decreased average pore diameter for NiS@CNFs nanocomposite by 2.53 folds when compared to that at CNFs. The electroactivity of NiS@CNFs nanomaterial for catalyzing urea electro-oxidation was investigated using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy measurements. Increased activity of this nanocatalyst was registered when urea molecules were added in increased concentrations into KOH solution. Lowered resistance values were also obtained describing the charge transfer process to confirm the feasibility of the studied reaction at NiS@CNFs surface. Moreover, its drawn chronoamperogram showed a stable performance during operation for long periods revealing a lowered catalytic decay. Accordingly, the aforementioned results of our fabricated nanomaterial could provide a good guide for fabricating suitable electrocatalysts for various electrocatalytic purposes.
Decorated carbon nanofibers with mixed nickel−manganese carbides for methanol electro-oxidation in alkaline solution
2021, International Journal of Hydrogen Energy
Transition metal carbides were recently investigated in many vital applications due to their satisfactory thermal, mechanical and chemical characteristics. They showed a metallic architecture of the host lattice containing interstitial voids of carbon atoms. In this work, mixed nickel-manganese carbides were synthesized onto carbon nanofibers [NiC–MnC@CNFs] in different proportions using the electrospinning process with subsequent calcination at 800 °C. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were employed to physically characterize the prepared nanomaterials. Homogeneous distribution of nanometallic particles over CNFs was clearly observed in SEM images. XRD charts detected the formation of mixed metallic carbides of Ni_0.98C_0.02 and (Mn₉C)_0.4 formulations in different nanomaterials. Excellent electrocatalytic behavior was displayed by NiC–MnC@CNFs nanocatalysts when methanol molecules were introduced into the alkaline solution. Methanol oxidation current density of 110.34 mA cm⁻² was measured at the nanomaterial containing NiAc:MnAc ratio of 90:10 with a lowered E_onset value of 310 mV (Ag/AgCl). The effect of varying methanol concentration and the scan rate during the electro-oxidation reaction on the resultant nanomaterial activity was studied. Moreover, the feasibility of charge transfer step was significantly affected by the chosen potential value. Highly pronounced rate was measured at 450 mV. The chronoamperometric study revealed a promising stability trend with increased steady state oxidation current densities especially at nanopowders with lowered MnAc wt.%. The synergistic effect between mixed metallic carbides and CNFs could account for the improved electrocatalytic properties towards methanol molecules oxidation.

View all citing articles on Scopus

¹: These authors are contributed equally in this work.

View full text

Regular ArticleFacile synthesis of GO@SnO2/TiO2 nanofibers and their behavior in photovoltaics

Abstract

Graphical abstract

Introduction

Section snippets

Materials

Morphology, crystallinity and chemistry of the prepared NFs

Conclusion

Acknowledgements

Ceram. Int.

J. Photochem. Photobiol., C

J. Power Sources

Chem. Eng. J.

Ceram. Int.

Int. J. Hydrogen Energy

Appl. Catal., B

Electrochim. Acta

Carbon

Mater. Sci. Eng., B

J. Colloid Interface Sci.

Chem. Eng. J.

Appl. Catal., B

Electrochim. Acta

J. Alloys Compd.

Electrochim. Acta

Dye-sensitized solar cells

Chem. Rev.

Nanoforest of hydrothermally grown hierarchical ZnO nanowires for a high efficiency dye-sensitized solar cell

Nano Letters

Ordered mesoporous SnO2− based photoanodes for high-performance dye-sensitized solar cells

J. Phys. Chem. C

A new type of transparent and low cost counter-electrode based on platinum nanoparticles for dye-sensitized solar cells

Energy Environ. Sci.

A review on counter electrode materials in dye-sensitized solar cells

J. Mater. Chem. A

Regular Article
Facile synthesis of GO@SnO₂/TiO₂ nanofibers and their behavior in photovoltaics

Ordered mesoporous SnO₂− based photoanodes for high-performance dye-sensitized solar cells