Research on the oxidation mechanism of C₂H₄ in automotive exhaust over MgO-supported Ag-Cu bimetallic synergistic catalysts

Ethylene (C2H4) in vehicle exhaust is a highly reactive volatile organic compound (VOC). Its photo-oxidative reaction with NOx contributes to the formation of O3 and secondary organic aerosols (SOA), the latter being a key precursor of PM2.5. In this study, a novel MgO-supported Ag-Cu bimetallic catalyst was designed and investigated using density functional theory (DFT). The effects of Ag and Cu loading on the geometric structure, stability, and reactant adsorption characteristics of the catalyst were analyzed, and the catalytic oxidation pathways of C2H4 over AgCu-MgO was elucidated. The results indicate that loading Ag significantly enhances the adsorption of C2H4. The incorporation of Cu into Ag-MgO to form a AgCu-MgO bimetallic catalyst (dual atom catalyst, DACS) further improves the oxidative activity toward C2H4. Based on the binding energies of the Ag and Cu bimetallic sites and the adsorption energies of C2H4 and O2, three representative configurations were selected for detailed reaction pathway analysis. Among them, Configuration 6 of AgCu-MgO exhibited the highest catalytic oxidation performance. This study provides new atomic-scale insights for the rational design of efficient catalysts targeting olefinic pollutants in automotive emissions and offers valuable guidance for advancing exhaust after-treatment technologies.