Nanoscopically-optimized carrier transportation and utilization in immobilized AuNP-TiO2 composite HER photocatalysts

Abstract Immobilized visible light-active composite HER photocatalysts are promising high-performance catalysts which take advantage of the synergy between the various building components; and they can be easily recycled and are relatively environmentally benign. However, structural and componential features remarkably regulate the catalytic processes and optimizations based on systematic studies on the mechanism of reactions using such catalysts are still lacking. In this report, we fabricate an interfacially immobilized composite AuNP-TiO2 catalyst using the layer-by-layer technique, which permits delicate tuning of the catalyst components and structural features down to the nanoscopiclevel. The influence of calcination, the diameter of the AuNPs, and the componential ratio between the two components have been studied. The results indicate that calcination is necessary for superior catalytic performance. AuNPs, possessing a 16 nm diameter, functions better than AuNPs with diameters of approximately 30 nm and 50 nm. The optimized componential ratio was identified at a moderate value with few or many AuNPs both hindering the photocatalytic HER performance. We believe that our study provides an effective strategy for the fabrication of superior HER photocatalysts (H2 production rate 5.21 mmol·g-1·h−1), and the mechanistic investigations can be used to optimize other noble metal–semiconductor composite catalysts.