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

Abstract

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 (PtP, PtSA, and PtC) were controlled by varying the impregnated solution. Experimental results demonstrate that PtC with intermediate size exhibits the highest photolysis rate under 300W 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 PtC/TiO2 has the narrowest band gap, the highest interfacial charge transfer capacity, and the greatest carrier separation efficiency. DFT calculations indicate that PtC/TiO2 has the most suitable d-band center, resulting in a close-to-zero ΔGH* 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.