Abstract
Converting CO2 waste into valuable chemicals through hydrogenation is promising for reducing atmospheric CO2 and promoting sustainable carbon recycling. Supported Pd catalysts are commonly studied for CO2 methanation, yet the pivotal role of interfacial Pd species remains unclear due to ambiguous experimental results, impeding further catalyst enhancements. This study uses theoretical calculations to explore how interfacial Pd sites influence catalytic performance in Pd-PdOx@TiO2 catalysts during CO2 methanation. Our findings show that H2 preferentially dissociates at Pd0 sites, while Pdδ+ sites primarily activate CO2. Adjusting the Pd0/Pdδ+ ratios optimizes the electronic properties of these sites, enhancing CO2 activation efficiency. The designed Pd21-Pd8O9@TiO2 nanocatalyst with adjusted electronic states significantly promotes electron transfer to CO2, favoring CH4 formation by stabilizing the *CH3 intermediate and reducing the activation barrier for its conversion to *CH4. These insights advance understanding of interface engineering in metal-support systems for CO2 hydrogenation.