Photoelectric Conversion Characteristic Of Three-Dimensional Graphene Composite Material

Photoelectrochemistry is a low-cost-way of utilizing solar energy, which is benefitto large-scale application. Recently, the rise of graphene inspires the improvement of the photoelectrochemical anode. Considering its high electron mobility and the large surface area, scientists attempt to improve the photoelectric conversion efficiency by graphene. But graphene has no energy gap, so it cannot be used as photoelectrochemical anode directly. In this paper, we prepared a photoelectrochemical anode composed by the three-dimensional graphene foamand Cd S nanomaterials. The microstructure’s characterization and composition of as-prepared-Graphene/Cd S compositewas given by a variety of characterization methods. The photoelectric conversion characteristics of the three-dimensional(3D) graphene/Cd S composite anode was studied by photoelectrochemical test. The main contents and innovations are listed as follows:1. The three-dimensional graphene foam was prepared by template-assisted chemical vapor deposition method. In this method, the nickel foam worked as a template.The qualitative analysis and quantitative analysis of the 3D graphene foam was given by scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS), Raman spectroscopy(Raman), atomic absorption spectroscopy(AAS), thermal gravimetric and simultaneous thermal analyzer(TGA). Results show the 3D graphene foamis assembled by many different layers of flawless graphene with a high conductivity and high surface area.2. The three-dimensional graphene/Cd S compositesis prepared by chemical vapor deposition method. The characterization of the composite material is carried out by X-ray diffraction pattern(XRD), Raman, SEM and EDS. The results show the growth temperature and deposition time are important factors in preparation of the composites.The amount of Cd S nanocrystals decrease by increasing the growth temperature and increase by increasing the deposition time. In addition, at the deposition temperature between 250-400 o C, one-dimensional Cd S nanocrystals in the composites were found.3. The photoelectric conversion characteristics of the three-dimensional graphene/Cd S composite anodeswerestudied by photoelectrochemical test. The results show, by the increasing amount of Cd S nanocrystal in the composites within a certain range, the photocurrent of composites increases. Compared with Cd S nanoparticles, theone-dimensional CdS nanocrystal can enhance photocurrent of anode. Among them, the Cd S nanoribbons are more effective to increase photocurrent than the Cd S nanowires.4. Finally, the results showed that the three-dimensional graphene/Cd S composites exhibit significantanode photo-corrosion. This anode photo-corrosion results from the reduced amount of Cd S nanomaterial on the surface of 3D graphene foam. Therefore,the anode photocurrent decreases with the photoelectrochemical reaction carries on.This result indicates that certain interface treatment technique is necessary to enhance the adhesive force between the Cd S and graphene.