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要旨

Electroreduction of CO₂ to value-added products is a promising strategy for CO₂ reuse, where copper has a unique ability to produce oxygenates and C₂₊ products. Unfortunately, the electronic factors making copper so unique are unknown, which limits our ability to design improved catalysts. By combining in situ surface sensitive X-ray resonant photoelectron spectroscopy with density functional theory calculations, we uncovered the complex electronic structure of copper during the electrocatalytic reduction of CO₂. We found that the pseudocapacitive charging of copper, produced by the incorporation of protons and electrons into the subsurface, facilitates the activation of CO₂, while simultaneously increasing the barrier for H-H coupling. The net result is that cathodic pseudocapacitive charge suppresses the hydrogen evolution reaction and promotes the production of hydrocarbons and oxygenated products on copper. These results represent a new paradigm in the understanding of CO₂ reduction, highlighting the key role of pseudocapacitive charge in the reaction.