Loading Pt clusters is more conducive to photocatalytic hydrogen evolution compared to single atoms and nanoparticles

Pt/TiO₂ photocatalysts were synthesized using incipient wetness impregnation followed by oxidative and/or reductive thermal treatments. The loading dimensions of Pt elements on the TiO₂ surface (Pt_P, Pt_SA, and Pt_C) were controlled by varying the impregnated solution. Experimental results demonstrate that Pt_C with an intermediate size exhibits the highest photolysis rate under 300 W xenon lamp irradiation, achieving a hydrogen yield of 11.42 mmol g^-1 h^-1 and an apparent quantum yield of 40.65%. Similarly, Ru/TiO₂ and Ir/TiO₂ photocatalysts prepared under the same conditions exhibited the same pattern. Photoelectrochemical tests reveal that Pt_C/TiO₂ has the narrowest band gap, the highest interfacial charge transfer capacity, and the greatest carrier separation efficiency. DFT calculations indicate that Pt_C/TiO₂ has the most suitable d-band center, resulting in a close-to-zero ΔG_H* value of 0.05 eV. This optimal value significantly balances the adsorption and desorption of hydrogen intermediates (H*) during the photocatalytic hydrogen evolution (PHE) reaction. This study provides new insights into the preparation of precious metal-loaded photocatalysts.