Nanoarchitectonics of a Au nanoprism array on WO₃ film for synergistic optoelectronic response

A layered photoelectrode consisting of a conductive indium tin oxide substrate, a WO₃ nanocrystalline film and an array of Au nanoprisms was fabricated via a multistep process. Scanning electron microscopy and atomic force microscopy showed that the Au nanoprisms had a uniform size and shape and formed periodic hexagonal patterns on the WO₃ film. The optical absorption of the photoelectrode combined the intrinsic absorption of WO₃ and plasmonic absorption of Au. Using this photoelectrode, we investigated the effect of the Au nanoprism array on the optoelectronic conversion performance of the WO₃ film. Photoelectrochemical measurement indicated that the array substantially enhanced the photocurrent in the WO₃ film. Electrochemical impedance measurements revealed that the Schottky junctions formed between Au and WO₃ can facilitate the separation of photogenerated carriers as well as the interfacial carrier transfer. In this study, we demonstrate that covering a semiconductor with plasmonic noble metal nanoparticles can improve its optoelectronic conversion efficiency.