Mechanistic Insights into Methanol Steam Reforming on PdCu(111) and PtCu(111) Bimetallic Catalysts
Methanol steam reforming (MSR) is a pivotal process for efficient hydrogen production. This study employs density functional theory (DFT) calculations to comparatively analyze the MSR reaction mechanism on PdCu(111) and PtCu(111) bimetallic surfaces. The investigation unveils how alloying modulates reaction pathways and overall catalytic performance. Notably, Cu sites stabilize adsorption of OH and CH2O species, whereas Pd/Pt sites exhibit preferential affinity for CO. This spatial site separation facilitates progression along the formate pathway. PdCu(111) demonstrates superior overall catalytic performance compared to PtCu(111), with water dissociation identified as the rate-determining step (RDS), featuring an activation energy of only 0.74 eV. The bimetallic synergy breaks the inherent contradiction between activity and selectivity of monometallic catalysts: Cu sites serve as a source of hydroxyl groups, while Pd/Pt sites enhance C–H bond cleavage efficiency, ultimately enabling high methanol conversion alongside low CO formation. From the perspectives of electronic structure and geometric configuration, this study establishes a theoretical framework to guide rational design of high-performance bimetallic catalysts for MSR.