Theoretical Investigation of Nanoscale Metal Clusters Supported on HxMoO3–y for CO2 Reduction

Abstract

The photothermal catalysis of carbon dioxide (CO₂) 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_xMoO_3–y is capable of completely converting CO₂ into methane (CH₄). In contrast, Pt-H_xMoO_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_xMoO_3–y-based catalytic systems. This study employs density functional theory to examine the mechanism of CO₂ reduction on Ru-H_xMoO_3–y. The d⁷ configuration of Ru enables the transfer of d electrons from the Ru-H_xMoO_3–y catalyst to CO via π-back-bond, which results in the weakening of the C–O bond and the preferential formation of CH₄. Moreover, Ru-H_xMoO_3–y has been identified as a promising candidate for the production of ethylene (C₂H₄), with its selectivity being adjustable through variations in reaction temperature and pressure. Our findings demonstrate that the performance of C–C coupling in H_xMoO_3–y-based catalysts is significantly influenced by the d configuration of the metal cluster. The theoretically designed Fe/Ru-H_xMoO_3–y exhibits the most favorable catalytic activity. These insights offer critical mechanistic guidance for the design of advanced photocatalysts to convert CO₂ into solar fuels.