How symmetry factors cause potential- and facet-dependent pathway shifts during CO2 reduction to CH4 on Cu electrodes

The deactivation of copper electrodes is a serious problem that can affect the scalability and deployment CO2 electrolyzers. effect generally attributed to cathodic deposition Fe Zn impurities from electrolyte. Herein, an experimental-theoretical study shows existence potential- facet-dependent pathways for reduction CH4 on Cu. small-overpotential pathway deactivates electrodes, while large-overpotential does not. Theoretical modeling traces origin *COH *CHO, two *CO hydrogenation products. *COH, which reduces *C (precursor coke), more stable than *CHO around equilibrium potential, but its symmetry factor smaller. Hence, *COH-based coking opens first until potential negative enough *CHO-based dominate. This highlights often-neglected role factors in electrocatalysis design suggests small increases *CHO’s mitigate Cu deactivation.