Enhanced visible-NIR absorption and oxygen vacancy generation of Pt/H_xMoWO_y by H-spillover to facilitate photothermal catalytic CO₂ hydrogenation

Photothermal catalytic hydrogenation of CO2 is an intriguing approach to reduce CO2 under mild conditions, which is possible because of photoinduced electron-hole pair generation and an overall increase in the localized temperature under light irradiation. However, the lack of a catalyst with an adequate photothermal conversion efficiency and the ability to generate a sufficient number of photoinduced electrons are the main factors limiting the applicability of this method. H-doped WOy demonstrates surface plasmon resonance (SPR) capabilities, and can be adjusted by changing the dopant (H+) concentration. To improve the potential of the WOy plasmonic effect based on H-doping, we herein report that the Mo-doped Pt/WOy (Pt/MoWOy) substantially increases the dopant (H+) and oxygen vacancy concentration in Pt/HxMoWOy during the H-2 reduction process, facilitating photothermal hydrogenation of CO2 to CO. The developed Pt/HxMoWOy exhibits excellent catalytic performance (3.1 mmol h(-1) g(-1)) in the photothermal reverse water-gas shift (RWGS) reaction at 140 degrees C, outperforming undoped Pt/HxWOy (1.02 mmol h(-1) g(-1)). Experimental and comprehensive analyses, including photoelectrochemical measurements, UV-Vis-NIR diffuse-reflectance spectroscopy, and a model reaction, showed that abundant surface free electrons and oxygen vacancies (V-O) in Pt/HxMoWOy are responsible for the efficient CO2 adsorption and transfer of photoinduced electrons to carry out the reduction of CO2 to CO. X-ray photoelectron spectroscopy (XPS) and in situ X-ray absorption fine structure (XAFS) measurements revealed a reversible redox event for the Mo and W atoms during the RWGS reaction, confirming that the oxygen vacancies between Mo and W atoms in Pt/HxMoWOy act as active sites and that Pt nanoparticles activate H-2 to enable the regeneration of the oxygen vacancies. Moreover, density functional theory (DFT) calculations demonstrated that Mo-doping substantially decreases the energy barrier for oxygen vacancy formation in WOy in the H-2 reduction process. We expect that this study will provide an innovative strategy for designing a highly efficient catalyst for photothermal CO2 conversion.