A DFT study and microkinetic analysis of CO oxidation to dimethyl oxalate over Pd stripe and Pd single atom-doped Cu(111) surfaces

Abstract

Developing low amount and high catalytic performance of Pd-based catalysts are vital for the oxidation of CO to dimethyl oxalate (DMO) in industry. In this study, Pd stripe and Pd single atom-doped Cu(111) surfaces are constructed via Pd substituting four striped Cu atoms and single Cu atom of surface layer over the Cu(111) surface, respectively, namely Pd4Cu8/Cu(111) and Pd1-Cu(111) surfaces, and two possible reaction pathways related to DMO synthesis have been studied on two surfaces employing density functional theory (DFT) calculation in combination with microkinetic analysis and subsequently compared with the cases of Pd(111) and PdML/Cu(111). The results show that COOCH3-COOCH3 coupling pathway is superior to COOCH3-CO on Pd4Cu8/Cu(111) and Pd1-Cu(111). Moreover, the Pd1-Cu(111) surface shows highest catalytic activity for DMO generation, followed by the Pd4Cu8/Cu(111), the Pd(111) and the PdML/Cu(111) surface. Additionally, Pd4Cu8/Cu(111) and Pd1-Cu(111) surfaces exhibit high DMO selectivity. Thus, Pd stripe and Pd single atom-doped Cu(111) surfaces are thought to be prospective candidates to improve the catalytic performance of noble Pd and reduce its usage for CO oxidation to DMO.