Catalytic oxidation mechanism of AsH over CuO@SiO core-shell catalysts via experimental and theoretical studies.

In this study, CuO@SiO core-shell catalysts were successfully synthesized and applied to efficiently remove hazardous gaseous pollutant arsine (AsH) by catalytic oxidation under low-temperature and low-oxygen conditions for the first time. In typical experiments, the CuO@SiO catalysts showed excellent AsH removal activity and stability under low-temperature and low-oxygen conditions. The duration of the AsH conversion rate above 90 % for the CuO@SiO catalysts was 39 h, which was markedly higher than that of other catalysts previously reported in the literature. The considerable catalytic activity and stability were attributed to the protection and confinement effects of the SiO shell, which resulted in highly dispersed CuO nanoparticles. Meanwhile, the strong interaction between the CuO core and SiO shell further facilitated the formation of active species such as coordinatively unsaturated Cu and chemisorbed oxygen. The accumulation of oxidation products (AsO and AsO) on the interface between the CuO core and SiO shell and the pore channels of the SiO shell is the main cause of catalysts deactivation. Furthermore, through combined density functional theory (DFT) calculations and characterization methods, a reaction pathway including gradual dehydrogenation (AsH*→AsH*→AsH*→As*) and gradual oxidation (2As*→As*+AsO*→2AsO*→AsO) for the catalytic oxidation of AsH on CuO (111) surface was constructed to clarify the detailed reaction mechanism. The CuO@SiO core-shell catalysts applied in this study could provide a powerful method for developing AsH catalysts from multiple know AsH removal systems.