Selective proton-coupled electron transfer regulated by potential of zero charge for CO₂electroreduction on tailored cobalt phthalocyanine

Surface charge, a pivotal interfacial parameter governing electrocatalytic performance, remains incompletely understood regarding its mechanistic impact on catalytic processes. Herein, the potential of zero charge of cobalt phthalocyanine (CoPc)/graphene systems is modified via terminated group engineering to unravel the role of surface charge in the CO₂ reduction reaction (CO₂RR). Our findings reveal that surface charge density exerts pronounced modulation over both the formation energies of reaction intermediates and the charge transfer characteristics within adsorbed species. Neither excessively high nor low surface charge densities favor CO₂-to-CO conversion, as *COOH formation energy exhibits greater surface charge sensitivity than *CO₂ and *CO. Conversely, elevated surface charge density facilitates enhanced charge transfer to adsorbed *CO, thereby promoting its hydrogenation and favoring CH₃OH synthesis. Furthermore, high surface charge density triggers spontaneous self-protonation of CoPc bridge nitrogen atoms, which severely compromises catalyst stability. This self-protonation event leads to depletion of surface charge density, elevation of intermediate formation energies, and redistribution of charge density within adsorbed species, collectively modulating catalytic activity, selectivity, and long-term stability. Our work establishes surface charge as a core variable for dynamically regulating electrocatalytic performance, offering fundamental insights for rational interfacial charge engineering in the CO₂RR and beyond.