Promoting Efficient H2 Dissociation in Photothermal CO2 Hydrogenation through Functional Separation and Synergistic Coupling of Active Sites

Abstract

Efficient H2 dissociation and subsequent spillover of active hydrogen species are critical factors for achieving high activity in CO2 hydrogenation reactions. Herein, we constructed a well-designed and highly dispersed Cu–In bimetallic catalyst supported on CeO2. This catalyst enables the spatial separation of plasmonic enhancement, H2 activation, and CO2 conversion sites, thereby significantly improving H2 dissociation capability and H-spillover efficiency. Comprehensive investigations using multiple transient characterizations, together with in situ/operando spectroscopy, reveal that the three components are tightly coupled through H-spillover, electron transfer, and interfacial interactions. Specifically, the Ce sites on the CeO2 surface serve as the active centers for CO2 conversion via a redox mechanism, while the available indirect but consistent evidence suggests that In species likely act as the primary H2 dissociation sites, promoting the reduction of Cu species and the regeneration of oxygen vacancies on the CeO2 surface through H-spillover. Meanwhile, the localized surface plasmon resonance (LSPR) effect of Cu significantly enhances the light absorption and photothermal conversion efficiency of the catalyst. The photoexcited LSPR electrons generated by Cu are further transferred to the In species and CeO2 surface, thereby facilitating H2 dissociation and the redox cycling of Ce sites. Such a “functional separation–synergistic enhancement” strategy effectively improves the catalytic activity, and the optimal catalyst achieves a CO yield of 230.1 mmol gcat–1 h–1 W–1 cm2 under 1.5 W cm–2 light irradiation at the surface temperature of 300 °C, significantly outperforming both the corresponding dark reaction and the monometallic Cu/CeO2 and In/CeO2 counterparts. This work provides important design principles and mechanistic insights for constructing highly active CO2 hydrogenation catalytic systems by enhancing H2 dissociation and H-spillover processes.