Mechanistic Insights into Ammonia Oxidation over Electron Transfer-Induced Pt–O–Cu Dual Sites

The low selectivity for N2 in the oxidation of NH3 over commercial Pt/Al2O3 catalysts is primarily due to the overoxidation of NH3 facilitated by Pt sites, leading to the formation of unwanted byproducts such as N2O and NO. In this study, we present a novel strategy to enhance N2 selectivity while maintaining NH3 conversion by constructing Pt–O–Cu dual sites. These dual sites exhibit synergistic acid-redox characteristics through surface electron transfer mediated by bridged lattice oxygen. Additionally, the ability of surface-adsorbed oxygen to exchange with lattice oxygen is significantly improved. The electron-deficient Cu sites enhance NH3 adsorption by providing empty 3d orbitals, while the electron-rich Pt sites promote NH3 dehydrogenation. Subsequently, the formation of –NH or –N intermediates at the Pt sites can react with adsorbed NH3 on the Cu sites to produce N2, predominantly following the integrated selective catalytic reduction mechanism. The optimized dual-site catalyst achieves over 95% NH3 conversion and N2 selectivity at 180 °C.