Investigation of the mechanism of methanol electrooxidation: a potential-dependent DFT study.

The methanol electrooxidation reaction (MER), a critical process in direct methanol fuel cells, is systematically investigated through potential-dependent density functional theory (DFT) simulations to unravel its mechanism and potential effects on Pt-based catalysts. For pure Pt, the rate-determining steps (RDSs) are identified as methanol adsorption and CO oxidation, leading to a high overpotential of 0.9 V. Alloying Pt with Cu (PtCu) significantly reduces the overpotential to 0.7 V, with CO oxidation remaining the sole RDS. Potential-dependent analysis reveals that PtCu exhibits enhanced methanol adsorption and weakened CO binding strength due to electronic structure modulation, effectively mitigating CO poisoning. Furthermore, multiple reaction pathways occur on PtCu surfaces, accelerating intermediate consumption. This work elucidates the regulatory effects of electrode potential on reaction thermodynamics, pathway selection, and adsorption behavior, providing theoretical insights for designing efficient and CO-tolerant bimetallic catalysts.