Enhancing Methane Combustion Activity by Modulating the Local Environment of Pd Single Atoms in Pd₁/CeO₂ Catalysts

Reducing methane emissions is crucial for mitigating global warming. Developing highly efficient catalysts for low-temperature methane combustion is of great importance. Supported single-atom catalysts (SACs) have received significant attention in this regard. However, their long-term stability and activity remain challenging. In this study, we present a method for creating a highly active and thermally stable Pd-1/CeO2 catalyst by using thermal-shock synthesis (Pd-1/CeO2-TS). By subjecting isolated Pd2+ ions to ultrafast shockwaves, we control their local environment, resulting in unique electronic structures and the geometry of the Pd single atoms. Compared with the single-atom Pd-1/CeO2 catalyst formed through atom trapping (Pd-1/CeO2-AT), Pd-1/CeO2-TS showed improved activity for methane combustion with a nearly 20-fold increase in turnover frequency and reversible stability against water. This increase in activity is attributed to the presence of coordination-unsaturated Pd-O species and surface hydroxyls on ceria. These factors enhance the oxygen activity and reduce the barrier for C-H bond activation, resulting in increased catalytic performance.