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.