Anion-Doping-Mediated\nMetal–Support Interactions\nin CeO<sub>2</sub>‑Supported Pd Catalysts for CO<sub>2</sub> Hydrogenation

The electronic and geometric robustness of active sites\nin catalysts\ndetermines their long-term efficiency in CO<sub>2</sub> hydrogenation.\nOne effective strategy to improve durability is rationalizing metal\nsite charge distribution through strong metal–support interactions\n(SMSIs). We propose an effective approach that can modulate the SMSI\nbetween Pd and CeO<sub>2</sub> by doping chlorine anions into the\nCeO<sub>2</sub> lattice. The developed Pd@CeOCl/CeO<sub>2</sub> catalyst\nexhibits sustainable activity (3150 mmol·g<sub>Pd</sub><sup>–1</sup>·h<sup>–1</sup>) and CO selectivity (99.7%) for at least\n200 h, as well as enhanced resistance toward CO and H<sub>2</sub>O.\nAnion-doping-mediated SMSIs result in significant electronic perturbations\nin the Pd<sup>δ+</sup>–[Cl–Ce–O]<sup>δ−</sup> interface, which modulates the surface properties and the energy\nband of the catalyst. Combined spectroscopic and microscopic evidence\nunveils that a Cl<sup>δ−</sup>–Cl<sup>–</sup> pair buffers the electron transfer in Pd<sup>δ+</sup>↔Pd<sup>0</sup> and Ce<sup>4+</sup>↔Ce<sup>3+</sup> cycles, which\ncircumvents the further hydrogenation of CO and shields Pd<sup>δ+</sup> sites from sintering in hydrogenation conditions.