A Cu–Pd single-atom alloy catalyst for highly efficient NO reduction†
A series of Cu–Pd alloy nanoparticles supported on Al2O3 were prepared and tested as catalysts for deNOx reactions. XRD, HAADF-STEM, XAFS, and FT-IR analyses revealed that a single-atom alloy structure was formed when the Cu/Pd ratio was 5, where Pd atoms were well isolated by Cu atoms. Compared with Pd/Al2O3, Cu5Pd/Al2O3 exhibited outstanding catalytic activity and N2 selectivity in the reduction of NO by CO: for the first time, the complete conversion of NO to N2 was achieved even at 175 °C, with long-term stability for at least 30 h. High catalytic performance was also obtained in the presence of O2 and C3H6 (model exhaust gas), where a 90% decrease in Pd use was achieved with minimum evolution of N2O. Kinetic and DFT studies demonstrated that N–O bond breaking of the (NO)2 dimer was the rate-determining step and was kinetically promoted by the isolated Pd.