Synthesis And Photoelectrochemical Properties Of The Composite Film Of Graphene And Tungsten Oxide

The photoelectric conversion of solar energy is an important way to solve the environmental pollution and energy shortage. Thus, researching and developing the semiconductor materials are the key point for the efficient utilization of solar energy. Among kinds of semiconductor photocatalytic materials, tungsten oxide (WO3) is one of the most promising materials because of its chemical stability and low cost. However, its photoelectric conversion efficiency is limited by the combination of electron and hole. In this study, the composite film of graphene and tungsten oxide is loaded on the FTO. And the double layer structured film, which has the behaviors of fast electron mobility and long optical path, is fabricated with the composite film as underlayer. WO3is modified by graphene for its high intrinsic electron mobility. The recombinations of photogenerated electron-hole are inhibited. And the photoelectric conversions of tungsten oxide based materials are enhanced. The main contents are as below.Firstly, the composite film of reduced graphene oxide and WO3(G-WNC) is fabricated via dip-coating with water-soluble polymer crosslinking agent. It can be found that the composition of the film is uniform and WO3nanocrystal of the composite is about20nm. The photocurrent of G-WNC with the thickness of3.5μm is0.96mA/cm at1.2V (vs. Ag/AgCl), which is2.13times of that of the WNC. For the precursor system with different concentration of GO, the photocurrent of film changes with the concentration of GO. When GO is0.960mg/mL in the precursor, the value of photocurrent is largest, which is2.07times of the pure WO3film.Secondly, transient photocurrent spectroscopy and intensity modulated photocurrent spectroscopy are used to study the transfer process and transport behaviors of charge carriers at the interface of film electrode under the photoelectric effect. Experiment results show that the transport rate of photoproduced electron is improved after incorporation of RGO. And the transport time of electron is reduced, which is only 47.5%of that of WNC. The recombination of electron and hole is inhibited via high electron mobility, and the life time of electron and hole is prolonged.Based on the aboved studies, a bilayer-structured film photoelectrode was designed and fabricated by solution-based and hydrothermal methods in order to improve the optical path and the capacity of electron transmission. After incorporation of RGO with WO3in the underlayer of bilayer structured film, the photocurrent of bilayer-structured film photoelectrode was incresed with53.8%at1.2V (vs. Ag/AgCl). When irradiated by the light at the wavelength of355nm, the incident photo to current conversion efficiency is increased to39.52%at the applied potential of1.0V. With the analysis of ultraviolet-visible diffused reflectance spectrum and IPCE, we found that the main effects of RGO are inhibiting the recombination of electron and hole, and promoting electron tranfer.Finally, the dye-sensitized solar cells are fabricated based on bilayer-structured films sensitived by N719. After incorporation of RGO, the photoelectric conversion efficiency of bilayer-structured film is0.067%, which is increased with60%. There are42figures,8tables and146references in this paper.