Oxygen Storage Capacity and CO Oxidation Performance of CeO2 Nano-Octahedra with Saturated In3+ Doping

CeO2is widely studied in catalysis owing to its Ce4+/Ce3+redox couple and oxygen storage capacity (OSC), but its low-temperature redox activity remains a challenge. To address this, this study investigates the effects of saturated In3+doping (1 mol.%) on the structural, redox, and catalytic properties of nano-octahedral CeO2. Structural and chemical analyses reveal that In3+doping induces lattice contraction from 5.4171 to 5.4129 Å, increases oxygen vacancy concentration from 29.7% to 39.8%, and raises surface Ce3+fraction from 27.6% to 30.0%. Consequently, H2-TPR measurements show that the surface reduction peak temperature decreases from 548 to 406 °C and the onset reduction temperature shifts from 309 °C to 183 °C. Quantitative OSC analysis further demonstrates that the low-temperature OSC increases from 13.17 to 20.57 mmol O2/mol and the high-temperature OSC from 53.36 to 59.38 mmol O2/mol upon doping. As a result of these enhancements, CO-TPSR tests reveal improved low-temperature CO oxidation performance, with the CO2light-off temperature decreasing from 99 to 72 °C and the rapid oxidation temperature from 153 to 96 °C. Notably, H2O and H2signals are detected during CO-TPSR, and FTIR analysis confirms the enrichment of surface hydroxyl groups in the doped sample, offering new mechanistic insights into the involvement of surface species in the reaction pathway. Overall, saturated In3+doping effectively enhances the oxygen vacancy concentration, surface reducibility, and CO oxidation activity of nano-octahedral CeO2.