Photo-controlled chemical states and the optimal size of Pt for enhancing the photo- and electrocatalytic hydrogen evolution reaction

The development of low-Pt catalysts is important for the large-scale application of Pt-based catalysts. Catalytic reactions mainly occur on the surface or interface of a material, and thus the surface properties of the catalyst will strongly affect their catalytic activity; this phenomenon has attracted widespread attention. Here, a series of Pt NPs with different chemical states and particle sizes were obtained by changing the light source wavelength, light time, and other conditions of light deposition synthesis. The Pt-TiO₂ catalyst has excellent potential in both photocatalytic hydrogen evolution (4.5 mmol·g⁻¹·h⁻¹) and electrocatalytic hydrogen evolution (26 mV@10 mA cm⁻²). We also found that the photocatalytic activity is more sensitive to the chemical state of Pt and that reducing the catalyst size can improve the electrocatalytic activity. This work not only provides a green and effective method to adjust the chemical state of precious metals on metal oxides but also helps to understand the impact of surface states on the catalytic process.