ZnO with spiked-nanosheet structure as photoanode for photoelectrochemical water splitting

Abstract

Photoelectrochemical water splitting (PEC-WS) is an interesting method to produce hydrogen from water by directly utilizing photon energy from the sunlight. Zinc oxide (ZnO) plays a crucial role as the photoanode in this system. ZnO with a certain nanostructure type has been reported to give distinctive results over other types when implemented as photoanode in PEC-WS. This indicates that a certain nanostructure might have more suitable electronic properties than the other for PEC-WS, thus studying the properties of various types of ZnO nanostructures becomes interesting to be explored. In this research, ZnO with a spiked-nanosheet structure is synthesized by a modified thermal evaporation method and implemented as the photoanode. The comparison with those made of commercial ZnO particles is also performed. Output photo-current obtained in this study is comparable to some of the previous reports even though the UV lamp power used in this study is smaller, suggesting the possibility of a better performance under standard 1-sun illumination. The ZnO photoanode layer made of ZnO powder with a spiked-nanosheet structure has a larger active surface area compared to those made of commercial ZnO particles. However, the output photo-current shows a smaller value, indicating a larger defect of the spiked-nanosheet structure leading to more severe recombination.