CO oxidation on Ni-based single-atom alloys surfaces

Abstract

CO oxidation on single-atom alloys (SAAs) surfaces is of potential importance in automobile industry. The relatively simple mechanism of CO oxidation reaction and the well-organized possible active sites in SAAs enable accurate modeling with theory, making the rational design of SAAs catalysts feasible. Van der Waals density functional theory (DFT), combined with micro-kinetic modelling, is used to study CO oxidation on 12 M-Ni(111) SAAs and pure Ni(111) surfaces. On Fe-, Co-, Ru-, Rh-, and Ir-Ni(111) SAAs surfaces, CO oxidation takes place over the region containing the alloying atom, while for the other SAAs, it occurs at the pure-Ni area. Micro-kinetic modelling reveals that Rh-Ni(111) SAA surface presents the largest reaction rate, followed by Au-Ni(111) and Ir-Ni(111) under our considered reaction conditions, consistent with the experimental observations on the corresponding nanoparticles. Among 12 SAAs, only Zn-Ni(111), Cu-Ni(111), and Cd-Ni(111) yields the poorer catalytic activity than pure Ni(111) for CO oxidation. The origin of catalytic reactivity sequence of SAAs for CO oxidation is discussed from the analyses of rate-limiting steps, electronic property and alloying effects.