The Nature of Active Sites for Plasmon-Mediated Photothermal Catalysis and Heat-Coupled Photocatalysis in Dry Reforming of Methane

Solar energy-induced catalysis has been attracting intensive interests and its quantum efficiencies in plasmon-mediated photothermal catalysis (P-photothermal catalysis) and external heat-coupled photocatalysis (E-photothermal catalysis) are ultimately determined by the catalyst structure for photo-induced energetic hot carriers. Herein, different catalysts of supported (TiO₂-P25 and Al₂O₃) platinum quantum dots are employed in photo, thermal, and photothermal catalytic dry reforming of methane. Integrated experimental and computational results unveil different active sites (hot zones) on the two catalysts for photo, thermal, and photothermal catalysis. The hot zones of P-photothermal catalysis are identified to be the metal–support interface on Pt/P25 and the Pt surface on Pt/Al₂O₃, respectively. However, a change of the active site to the Pt surface on Pt/P25 is for the first time observed in E-photothermal catalysis (external heating temperature of 700 °C). The hot zones contribute to the significant enhancements in photothermal catalytic reactivity against thermocatalysis. This study helps to understand the reaction mechanism of photothermal catalysis to exploit efficient catalysts for solar energy utilization and fossil fuels upgrading.