Why Is Methanol Formation Suppressed in CO2 Reduction Over Copper Electrocatalysts?

Electrocatalytic CO2 reduction (CO2RR) to produce methanol (CH3OH) provides a sustainable alternative to its energy-intensive industrial synthesis. However, C2+ species and CH4 are typically the dominant products on prototypical Cu catalysts, with no CH3OH formation. Herein, employing constant-potential explicit solvent methods, we systematically compared the thermodynamics and kinetics of C2+ products (covering 21 possible C-C coupling paths), CH4, and CH3OH formation to uncover the origin of intrinsic suppression of CH3OH. Nine C-C coupling pathways exhibit significantly lower barriers than C1 products, underscoring the facile formation of C2+ products via multiple accessible routes beyond conventional CO-CO coupling. For C1 products, the selectivity-determining intermediate *CH2OH favors C-O bond cleavage toward CH4 rather than hydrogenation to CH3OH, placing CH3OH formation at a kinetic disadvantage. This mechanism remains valid irrespective of Cu surface structures or applied potentials, and simulated Faradaic efficiencies (FE) align well with experimental trends, further validating our theoretical insight. Building on this, we propose a strategy that involves redirecting the pathway from *COOH to *HCOO and selectively stabilizing *CH2OH to steer its hydrogenation toward CH3OH. These findings establish a foundation for selective CH3OH production and highlight its synthesis as a key direction in electrocatalytic CO2 conversion.