Elucidating the Respective Roles of Photochemical and Photothermal Effects in Photocatalytic Methanol Decomposition

Photocatalytic reactions can be driven by both photochemical and photothermal processes. However, their individual contributions and synergistic effect remain to be clarified. Herein, we investigated the respective roles of these effects using a Cu-TiO₂/Ti model catalyst that integrated photochemical and photothermal functionalities within a single photocatalytic system. Employing photocatalytic methanol decomposition as a model reaction, the Cu-TiO₂/Ti catalyst achieved a high H₂ yield rate of 0.511 mmol h^-1 with selectivity of 96.6% toward HCHO among oxidation products, attributed to the cooperative action of photochemical and photothermal processes. In situ resonant Auger electron spectroscopy (RAS), together with in situ Cu K-edge X-ray absorption fine structure and excited-state density functional theory calculations, revealed the accumulation of photogenerated electrons at Cu sites from TiO₂, suggests the possible formation of an electron transfer pathway from TiO₂ to Cu, which promotes stepwise methanol dehydrogenation to HCHO and H₂. Simultaneously, the photothermal contribution from Ti enhanced catalytic activity by accelerating reaction kinetics and promoting the desorption of HCHO, thereby suppressing its overoxidation to CO.