A synergistic photothermal-dual site strategy to accelerate proton–electron transfer enables enhanced CO2-to-syngas conversion

Abstract

Efficient photocatalytic CO₂ reduction necessitates optimal charge balance and proton migration between the CO₂ reduction and H₂O oxidation half-reactions. However, traditional research has predominantly focused on optimizing these half-reactions independently, neglecting potential synergistic effects. Here, this work demonstrates a photothermal catalyst of Pt/Ta₂O_5−x nanoplates that synergistically leverages the photothermal effect and redox dual-site cooperation to simultaneously accelerate the CO₂ reduction and H₂O oxidation, thereby maximizing proton–electron transfer. The integration of the photothermal effect and photocatalysis ensures a strong driving force for CO₂ conversion while accelerating proton migration, with Pt plasmonics generating localized heat from solar energy. In situ characterization reveals that O vacancies in Ta₂O_5−x enhance H₂O dissociation to provide abundant protons, while Pt acts as an electron acceptor site, effectively activating the CO bond. Theoretical calculations further illustrate synergistic CO₂ reduction and H₂O oxidation on Pt and O vacancy sites, where the oxidation of *OH to *OOH is synchronized with the *CO desorption to CO, significantly lowering the energy barrier for proton-coupled electron transfer. Impressively, Pt/Ta₂O_5−x exhibits exceptional photothermal catalytic performance in CO₂-to-syngas conversion with a syngas yield up to 1.97 mmol g⁻¹ h⁻¹, which is 16.3-fold higher than that of Ta₂O_5−x. Furthermore, the apparent quantum efficiency reaches 3.5% at 365 nm, and the syngas selectivity is a remarkable 82%, while also exhibiting good stability.