Abstract
Improving the efficiency of photocatalysts for hydrogen production while minimizing the amount of noble metals used is a pressing issue in modern green energy. This study examines the effect of ultra-small Pt additives on increasing the efficiency of the CuO(x)-dark TiO(2) photocatalyst used in the hydrogen evolution reaction (HER). Initially, Pt was photoreduced from the hydroxonitrate complex (Me(4)N)(2)[Pt(2)(OH)(2)(NO(3))(8)] onto the surface of nanodispersed CuO(x) powder obtained by pulsed laser ablation. Then, the obtained Pt-CuO(x) particles were dispersed on the surface of highly defective dark TiO(2), so that the mass content of Pt in the samples varied in the range from 1.25 × 10(-5) to 10(-4). The prepared samples were examined using HRTEM, XRD, XPS, and UV-Vis DRS methods. It has been established that in the Pt-CuO(x) particles, platinum is mainly present in the form of single atoms (SAs), both as Pt(2+) (predominantly) and Pt(4+) species, which should facilitate electron transfer and contribute to the manifestation of the strong metal-support interaction (SMSI) effect between SA Pt(n+) and CuO(x). In turn, in the Pt-CuO(x)-dark TiO(2) samples, surface defects (O(v)) and surface OH groups on dark TiO(2) particles act as "anchors", promoting the spontaneous dispersion of CuO(x) in the form of sub-nanometer clusters with the reduction of Cu(2+) to Cu(1+) when localized near such O(v) defects. During photocatalytic HER in aqueous glycerol solutions, irradiation was found to initiate a large number of catalytically active Pt(0)-CuO(x)-O(v)-dark TiO(2) centers, where the SMSI effect causes electron transfer from titania to SA Pt, thus promoting better separation of photogenerated charges. As a result, ultra-small additives of Pt led to up to a 1.34-fold increase in the amount of released hydrogen, while the maximum apparent quantum yield (AQY) reached 65%.