High-Performance Ag Cu Nanoalloy Catalyst for the Selective Catalytic Oxidation of Ammonia

High-performance Ag-Cu alloy nanoparticles (NPs) were successfully synthesized by a solventless mix-bake-wash method and tested for NH3-SCO. The prepared Ag2Cu1 catalyst with a perfect Ag-Cu alloy structure exhibited better T-100 (200 degrees C, the temperature at which 100% NH3 conversion was obtained), higher reaction rates, and lower E-a compared to that with ordinary bimetallic Ag-Cu (AgCuOx). The characterization data revealed much smaller Ag-Cu alloy nanoparticles of the Ag2Cu1 catalyst and more Ag-Cu metallic species on the surface, which can increase the amount of chemisorbed surface oxygen (O-beta) and enhance NH3 adsorption and activation in the low-temperature range, therefore leading to a much higher NH3-SCO activity. Kinetic studies and density functional theory calculations indicated that Cu decoration at Ag by Ag-Cu alloying could enhance the adsorption/activation of NH3 and O-2. It has been found that O-2 was more easily transformed from the adsorption state to the transition state than NH3, which enhanced the performance of NH3 oxidation. In addition, the Ag2Cu1 catalyst exhibited excellent durability because of the stabilization of Ag sites by the Ag-Cu alloy structure.