Anion-Doping-Mediated Metal–Support Interactions in CeO₂-Supported Pd Catalysts for CO₂ Hydrogenation

The electronic and geometric robustness of active sites in catalysts determines their long-term efficiency in CO2 hydrogenation. One effective strategy to improve durability is rationalizing metal site charge distribution through strong metal–support interactions (SMSIs). We propose an effective approach that can modulate the SMSI between Pd and CeO2 by doping chlorine anions into the CeO2 lattice. The developed Pd@CeOCl/CeO2 catalyst exhibits sustainable activity (3150 mmol·gPd–1·h–1) and CO selectivity (99.7%) for at least 200 h, as well as enhanced resistance toward CO and H2O. Anion-doping-mediated SMSIs result in significant electronic perturbations in the Pdδ+–[Cl–Ce–O]δ− interface, which modulates the surface properties and the energy band of the catalyst. Combined spectroscopic and microscopic evidence unveils that a Clδ−–Cl– pair buffers the electron transfer in Pdδ+↔Pd0 and Ce4+↔Ce3+ cycles, which circumvents the further hydrogenation of CO and shields Pdδ+ sites from sintering in hydrogenation conditions.