Enhanced Charge Transfer Kinetics in Hematite Photoanodes via Au Nanoclusters─Toward Efficient Light-Driven Hydrogen Generation

Abstract

In these studies, we explain the mechanism by which gold nanoparticles enhance the photoelectrochemical activity of thin films of hematite. The electrodes were manufactured using magnetron sputtering in combination with inert gas condensation, one of the most advanced techniques to decorate the top material layer with metallic nanoclusters. Adjusting the very low surface concentration of widely separated Au nanoclusters, corresponding to 2.3% surface coverage, we observed a 2-fold increase in photocurrent values. This effect can be explained by electrochemical impedance spectroscopy results, which show an increase in charge carriers density by 1.7 and charge carriers lifetime by 1.4. Comprehensive in-depth microscopic and spectroscopic studies of the morphological, chemical, and electronic properties of hematite allow not only the characterization of the material but also the determination of the role of metallic Au nanoclusters at the electrode–electrolyte interface. Understanding the mechanism of the interactions between hematite and metallic Au nanoclusters is a key factor in designing advanced sustainable devices for solar-to-chemical energy conversion.