Catalytic Activity of the Transition-Metal Atom Doped Platinum Surface for NO Reduction by CO

The formation of bimetallic surface alloy catalysts is one of the most promising methods to improve the NO reduction activity of three-way catalysts. Here, the reduction of NO by CO on (100) and (111) surfaces of a series of transition metal (TM)-Pt alloy catalysts (TM = Fe, Co, Ni, Ru, Rh, Pd, Os, and Ir) was systematically studied by a density functional theory calculation and a microkinetics simulation. Under the actual reaction conditions, the surface alloy systems are stable, and TM doping enhances the adsorption strength of NO. On the basis of the dissociation energy barrier of NO, five TM-Pt(100) (Fe, Co, Ni, Rh, Ir) and three TM-Pt(111) (Fe, Co, Ni) were selected to study the overall reaction mechanism of NO+CO. Possible elementary steps for three N-containing products (N₂, N₂O, and NO₂) and CO₂ were considered. Microkinetic calculations further demonstrate that the conversion rates [turnover frequency] of products and product selectivity toward N₂ are improved in varying degrees on TM-Pt alloy catalysts. This work indicates that Fe–Pt(100), Co–Pt(100), and Ni–Pt(111) can be the optimal catalysts for NO reduction by CO, with a high N₂ conversion rate and nearly 100% N₂ selectivity in the whole temperature range of 300–1000 K.