Operating Solar-Driven Selective Photothermal CO₂ Hydrogenation via Regulating the Synergistic Interaction of Acid–Base Sites and Oxygen Vacancy over Three-Dimensional Ni-Based Microsphere Catalysts

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This study reported a strategy to synergistically regulate the product selectivity of CO2 hydrogenation by modulating acid–base sites and oxygen vacancies. Designing a series of three-dimensional Ni-based microsphere catalysts (Ni/C–MOx, M = Ce, Pr, La and In) were applied for photothermal CO2 hydrogenation. As a result, Ni/C–In2O3 achieved a CO2 conversion of 33.26% with nearly 100% CO selectivity through Lewis acidic sites formed by the exposure of In3+ cations. Besides, Ni/C–CeO2 established a preferred pathway for methanation by achieving a CO2 conversion of 34.67% with a 64.66% CH4 selectivity and a 22.5 mmol g–1 h–1 yield via a synergistic mechanism involving the Ce3+-induced electron transfer, the promotion of CO2 adsorption and activation by O2– acting as a basic site, and the strong Ni–CeO2 interaction. In situ DRIFTS revealed that HCOO* was a key intermediate in the methanation process, and light illumination accelerates its conversion, thereby promoting methane formation. This study provides theoretical support for the design of solar-driven photothermal catalysts.