Pt Single Atoms as Co-Catalysts on CdS-Sensitized Single-Crystalline TiO2 Nanoflakes for Enhanced Visible Light Photocatalytic H2 Generation

Abstract

Studies on single-atom catalysts (SACs) with individually isolated metal atoms anchored on specific supports have gained great interest in photocatalysis due to their enhanced catalytic activity and optimal atom utilization. By providing an optimized number of active sites and enhancing their intrinsic activity, SACs afford a distinctive platform for photocatalysis at the atomic level. In this study, we investigate the photocatalytic H2 generation of Pt single atoms (SAs) anchored on CdS-sensitized single crystalline anatase TiO2 nanoflakes (ATNF) in the visible spectral range. Vertically-aligned ATNF were synthesized on fluorine-doped tin oxide substrates by a hydrothermal process, which were further sensitized by CdS nanoislands (NIs) using the successive ionic layer adsorption and reaction (SILAR) technique. Finally, a reactive-deposition approach was used to successfully anchor Pt SAs on CdS-sensitized ATNF. Under optimized conditions, the highest photocatalytic H2 evolution on Pt-anchored single atom CdS sensitized ATNF was 17.8 μL h−1 under visible light illumination, which is 15.8, 7.5, and 6.7-fold higher than bare CdS/FTO, PtSA/CdS/FTO, and ATNF, respectively. Overall, the density of Pt SAs plays a vital role via strong trapping of the photogenerated electrons and significantly improves the efficiency of electron-hole separation, making PtSA/ATNF efficient solar-driven photocatalysts.