Why Is Methanol Formation Suppressed in CO ₂ 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.