Pt 助剂的尺寸调控及其对光催化 CO₂ 制 CH₄ 性能的影响

Platinum is one of the most efficient cocatalysts for photocatalytic reduction of carbon dioxide (CO2) to methane (CH4), but it still suffers from low CO2 reduction rate and low selectivity of CH4. In this study, Pt/TiO2 catalysts with adjustable Pt particle size (0.55−1.80 nm) were prepared by atomic layer deposition (ALD) and used for photocatalytic reduction of CO2 to CH4. The CH4 yield and selectivity of the Pt/TiO2 catalysts showed a volcanic variation trend with the increase of Pt particle size. The 10Pt/TiO2 with Pt particle size of 1.35 nm exhibit the highest methane yield (71.9 μmol/(g·h)). Especially, a high electron-based selectivity of 81.69% for CH4 (product-based selectivity of 90.20%), and 100% for hydrocarbons (CH4, C2H6 and C3H8) are achieved, no H2 formation was detected. The CO-DRIFTS, XPS, CO2-TPD, H2O-TPD, and H2-TPD characterizations suggest that the 10Pt/TiO2 exhibited optimal CO2 adsorption/activation capacity, suitable H2O activation capacity, and higher hydrogen desorption temperature, making the generation rate of active hydrogen species from H2O matches their consumption rate for CO2 hydrogenation. This study opens an avenue for rationally designing highly efficient and selective photocatalysts for photocatalytic CO2 reduction.