Enhancing CO₂ methanation via synergistic multi-valence Pd⁰− Pd^δ+ interactions on TiO₂

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-PdO_x@TiO₂ catalysts during CO₂ methanation. Our findings show that H₂ preferentially dissociates at Pd⁰ sites, while Pd^δ+ sites primarily activate CO₂. Adjusting the Pd⁰/Pd^δ+ 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. © 2024 Elsevier B.V.