Exploration of Gas-Dependent Self-Adaptive Reconstruction Behavior of Cu₂O for Electrochemical CO₂ Conversion to Multi-Carbon Products

Structural reconstruction of electrocatalysts plays a pivotal role in catalytic performances for CO₂ reduction reaction (CO₂RR), whereas the behavior is by far superficially understood. Here, we report that CO₂ accessibility results in a universal self-adaptive structural reconstruction from Cu₂O to Cu@Cu_xO composites, ending with feeding gas-dependent microstructures and catalytic performances. The CO₂-rich atmosphere favors reconstruction for CO₂RR, whereas the CO₂-deficient one prefers that for hydrogen evolution reaction. With the assistance of spectroscopic analysis and theoretical calculations, we uncover a CO₂-induced passivation behavior by identifying a reduction-resistant but catalytic active Cu(I)-rich amorphous layer stabilized by *CO intermediates. Additionally, we find extra CO production is indispensable for the robust production of C₂H₄. An inverse correlation between durability and FE_CO/FE_C2H4 is disclosed, suggesting that the self-stabilization process involving the absorption of *CO intermediates on Cu(I) sites is essential for durable electrolysis. Guided by this insight, we design hollow Cu₂O nanospheres for durable and selective CO₂RR electrolysis in producing C₂H₄. Our work recognizes the previously overlooked passivation reconstruction and self-stabilizing behavior and highlights the critical role of the local atmosphere in modulating reconstruction and catalytic processes.