Hollow Hierarchical Cu₂O‐Derived Electrocatalysts Steering CO₂ Reduction to Multi‐Carbon Chemicals at Low Overpotentials

Abstract The electrochemical reduction of carbon dioxide into multi‐carbon products (C₂₊) using renewably generated electricity provides a promising pathway for energy and environmental sustainability. Various oxide‐derived copper (OD‐Cu) catalysts have been showcased, but still require high overpotential to drive C₂₊ production owing to sluggish carbon–carbon bond formation and low CO intermediate (*CO) coverage. Here, the dilemma is circumvented by elaborately devising the OD‐Cu morphology. First, computational studies propose a hollow and hierarchical OD‐Cu microstructure that can generate a core–shell microenvironment to inhibit CO evolution and accelerate *CO dimerization via intermediate confinement and electric field enhancement, thereby boosting C₂₊ generation. Experimentally, the designed nanoarchitectures are synthesized through a heteroseed‐induced approach followed by electrochemical activation. In situ spectroscopic studies further elaborate correlation between *CO dimerization and designed architectures. Remarkably, the hierarchical OD‐Cu manifests morphology‐dependent selectivity of CO₂ reduction, giving a C₂₊ Faradaic efficiency of 75.6% at a considerably positive potential of −0.55 V versus reversible hydrogen electrode.