First-Principles Study of NO Reduction by CO on Cu2O(110) and Pd1/Cu2O(110) Surfaces

Selective catalytic reduction of NO by CO (CO-SCR) is considered as one of the most effective methods for simultaneous removal of two pollutants. The main challenge to achieve this goal is to develop a low-cost, highly effective, and stable catalyst. In this work, on the basis of experimental study, we designed a Pd1/Cu2O(110) single-atom catalyst to improve the selectivity of Cu2O to N2. The reaction mechanisms of NO reduction by CO on the undoped Cu2O(110) and Pd1/Cu2O(110) were studied by using density functional theory and microkinetic models, and the catalytic performance of the two catalysts was compared. The results showed that both surfaces have high CO oxidation activity. Pd doping improves the adsorption strength of NO and CO and changes the preferential configuration of NO on the surface with oxygen vacancies. Possible reaction pathways for the formation of N2 and N2O were located. Microkinetic analysis showed that the overall NO conversion rate and CO2 formation rate on Pd1/Cu2O(110) are much higher than those on Cu2O(110). Compared with the 100% selectivity of N2O on Cu2O(110) at 300–450 K, doping a single Pd atom into the top layer of Cu2O(110) can obtain 100% N2 selectivity in the whole temperature of 300–1000 K. It is further confirmed that the reaction proceeds via the different mechanism on the undoped and Pd-doped surfaces. N2O is formed on Cu2O(110) via the intermediate NNO, while N2 is formed on Pd1/Cu2O(110) via the dimer ONNO. This study is expected to provide a clue for the design of oxide-supported single-atom catalysts for NO reduction.