Microenvironmental Effects on CO₂ Hydrogenation Over PdZn Alloy Catalysts

Understanding catalytic reactions under realistic gas-phase conditions is essential for the computational design of next-generation industrial catalysts with enhanced efficiency and selectivity. In this work, a hybrid quantum/classical framework is employed to systematically investigate the effects of partial pressure, temperature, and surface coverage on CO₂ hydrogenation over PdZn alloy catalysts. The multiscale approach incorporates local gas-phase densities and realistic catalyst structures, enabling accurate prediction of reaction selectivity across operating conditions. The results reveal a temperature-dependent shift in pressure response: at low temperatures, increasing pressure favors the COOH pathway, while at elevated temperatures, the HCOO pathway becomes more competitive as pressure increases. This opposite trend reflects a competition of long-range and short-range interactions between gas molecules and intermediates, which evolves nonlinearly with the system pressure. The surface structure further modulates catalyst-environment interactions by altering local gas accessibility, for example, through suppressing CO₂ adsorption while promoting the catalyst binding of smaller molecules like H₂. These findings provide a detailed mechanistic understanding of how catalyst structure and reaction environment jointly regulate free-energy pathways in CO₂ hydrogenation. The transferable strategy of integrating microenvironmental effects into first-principles modeling advances the rational design of catalytic systems for efficient CO₂ utilization and broader chemical transformations.