WO3 mesoporous nanostructures-based composite photoanodes for improved photoelectrochemical performance

Abstract

In recent years, hydrogen is widely regarded as the solution to the current problems associated with the use of fossil fuels. However, most of the world’s hydrogen is currently produced from fossil fuels, which does little to solve the issues with fossil fuel usage. As such, photoelectrochemical (PEC) cell is introduced to produce hydrogen from renewable energy, specifically solar energy. In this project, nanostructured WO3 was combined with a secondary material to form a heterojunction photoanode. Specifically, the photoanodes fabricated were WO3 mesoporous layer/BiVO4 and WO3 inverse opals (WO3-IOs)/Bi2S3 nanowires heterojunction photoanode. Heterojunction engineering was done to optimize the photoanode quality, and the photoanode performance was measured by solar simulation in a three-electrode system configuration. The performance results of the photoanodes were then compiled and compared with each other. The results of the WO3 mesoporous layer/BiVO4 photoanode shows that the WO3 mesoporous triple layer/30 μl BiVO4 was the best performing photoanode, with photocurrent density of approximately 2.4 mA/cm2 at 0.4 V., which can be attributed to the enhanced charge generation and separation through the structural optimization. To further increase the performance, other fabrication methods for the BiVO4 films should be developed. On the other hand, three-dimensional WO3 IOs were fabricated by a dip-coating method. Bi2S3 nanowires were then grown on the WO3 IOs, which have the potential to form a new composite photoanode. As such, more work needs to be to optimize the performance of WO3-IOs/Bi2S3 nanowires photoanode.