Theoretical Investigation of Nanoscale Metal Clusters Supported on H_xMoO_3–y for CO₂ Reduction

The photothermal catalysis of carbon dioxide (CO 2 ) reduction into value-added solar fuels represents a promising approach to addressing the energy crisis and mitigating global warming. Recent experimental findings indicate that Ru-H x MoO 3– y is capable of completely converting CO 2 into methane (CH 4 ). In contrast, Pt-H x MoO 3– y has been observed to produce a range of products, with carbon monoxide (CO) being the most prevalent. A comprehensive understanding of the reaction mechanism is essential to elucidate the different sensitivities of catalysts and to facilitate the development of H x MoO 3– y -based catalytic systems. This study employs density functional theory to examine the mechanism of CO 2 reduction on Ru-H x MoO 3– y . The d 7 configuration of Ru enables the transfer of d electrons from the Ru-H x MoO 3– y catalyst to CO via π-back-bond, which results in the weakening of the C–O bond and the preferential formation of CH 4 . Moreover, Ru-H x MoO 3– y has been identified as a promising candidate for the production of ethylene (C 2 H 4 ), with its selectivity being adjustable through variations in reaction temperature and pressure. Our findings demonstrate that the performance of C–C coupling in H x MoO 3– y -based catalysts is significantly influenced by the d configuration of the metal cluster. The theoretically designed Fe/Ru-H x MoO 3– y exhibits the most favorable catalytic activity. These insights offer critical mechanistic guidance for the design of advanced photocatalysts to convert CO 2 into solar fuels.