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

Pt/TiO photocatalysts were synthesized using incipient wetness impregnation followed by oxidative and/or reductive thermal treatments. The loading dimensions of Pt elements on the TiO surface (Pt, Pt, and Pt) were controlled by varying the impregnated solution. Experimental results demonstrate that Pt with an intermediate size exhibits the highest photolysis rate under 300 W xenon lamp irradiation, achieving a hydrogen yield of 11.42 mmol g h and an apparent quantum yield of 40.65%. Similarly, Ru/TiO and Ir/TiO photocatalysts prepared under the same conditions exhibited the same pattern. Photoelectrochemical tests reveal that Pt/TiO has the narrowest band gap, the highest interfacial charge transfer capacity, and the greatest carrier separation efficiency. DFT calculations indicate that Pt/TiO has the most suitable d-band center, resulting in a close-to-zero Δ 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.