Evolution of the hydrothermal aging mechanism in Ni/CeO2 catalysts for N2O decomposition based on surface effect

The utilization of Ni/CeO 2 catalysts for direct catalytic decomposition of N 2 O represents a promising technological pathway to mitigate N 2 O emissions from ammonia-fueled combustion. This study investigated the influence of Ni doping on the N 2 O decomposition process over both fresh and hydrothermal aging CeO 2 catalysts through simulated gas test bench. By combining comprehensive physicochemical characterization with DFT calculations, the hydrothermal aging mechanism underlying the deterioration of catalytic activity and physicochemical properties in Ni/CeO 2 catalysts was elucidated. The findings revealed that hydrothermal aging was accompanied by crystallite growth and textural deterioration. Further, hydrothermal aging altered the crystal structure of Ni/CeO 2 via edge/corner truncation, resulting in a decreased Ce 3+ /Ce 4+ ratio, an increased O II /O I ratio, and consequently, a reduction in the comprehensive combustion index ( S ) and combustion stability index ( R w ) for N 2 O decomposition. Ni doping was found to modify the catalytic activity of CeO 2 by regulating the adsorption energies of N 2 O and H 2 O molecules on low-Miller-index surfaces. The Gibbs free energy changes induced by H 2 O adsorption on these low-index surfaces (153.6 °C → 430.2 °C → 531.4 °C) were identified as the primary cause for the directional surface migration of CeO 2 , which ultimately led to the degradation of the catalytic activity of Ni/CeO 2 catalysts. • Ni doping enhances N 2 O decomposition and hydrothermal stability. • Hydrothermal aging triggers edge truncation and Ni exsolution. • DFT shows Ni narrows CeO 2 band gap and weakens H 2 O adsorption. • Surface thermodynamics shows H 2 O drives CeO 2 (111 → 110/100) surface evolution.