A theoretical study into the performance of DACs loaded on MgO utilized in CO oxidation

Abstract

Single-atom catalysts (SACs) have garnered significant attention due to their unique combination of advantages from both heterogeneous and homogeneous catalysts. However, SACs composed of just one metal cannot adequately meet the various catalytic requirements. Thus, this study focused on the addition of a second metal atom to M1/MgO systems (M = Au, Ag and Cu) to create dual-atom catalysts (DACs) supported on different di-vacancy types on MgO(100) surfaces. Homogeneous (Au2, Ag2, Cu2) and multiphase (Au1Ag2, Au1Cu2 and Ag1Cu2) were analyzed for their selectivity in CO oxidation by Langmuir-Hinshaw (LH) and Eley-Rideal (ER) mechanisms using density functional theory (DFT) method. The results indicated that the tri-molecules ER pathway had the highest selectivity, and the multiphase DACs had better CO catalytic oxidation activity compared to homogeneous DACs. Among all multiphase DACs in the tri-molecules ER pathway, alloy DACs of Au1Ag2/MgO(Fc-Fc) and Au1Cu2/MgO(Fc-Vc) had the lowest energy barrier for CO oxidation, and the addition of a second metal atom improved stability compared to SAC of Au1/MgO(Fc). DFT calculations combined with microkinetic simulations revealed that under reaction conditions, Au1Cu2/MgO(Fc-Vc) had a remarkably high TOF of CO2, making it a promising DAC for practical applications. This study provides valuable insights into the development of efficient and low-cost atomic-scale catalysts.