Strong Electronic Interactions of the Abundant Cu/Ce Interfaces Stabilized Cu ₂ O for Efficient CO ₂ Electroreduction to C ₂₊ Products under Large Current Density

Abstract Copper‐based nanocatalysts, represented by Cu ₂ O nanocubes, are crucial for electrocatalytic CO ₂ conversion to C ₂₊ products but face significant stability challenges. Structural reconstruction from Cu dissolution and reduction under negative potentials undermines their long‐term stability. Herein, a novel Cu ₂ O@CeO _x core‐shell nanocatalyst is introduced, featuring a Cu ₂ O nanocube core encapsulated by an amorphous CeO _x shell. Due to the facilitated electron transfer of abundant Cu/Ce interfaces, the CeO _x shell layer simultaneously prevents the agglomeration and maintains the oxidation state of Cu ₂ O nanocubes, bringing in significantly improved stability. Unlike conventional coating layers, the defective CeO _x shell uniquely avoids obstructing mass transfer while effectively promoting the activation of CO ₂ and optimizing the electronic structure of Cu. The Cu ₂ O@CeO _x nanocatalyst delivers a remarkable C ₂₊ Faradaic efficiency exceeding 80% at 300 mA cm ⁻² under a low applied potential of −0.98 V, with exceptional durability lasting over 50 h, compared to just 2 h for Cu ₂ O alone. This work presents an effective strategy to enhance catalyst stability without sacrificing activity, advancing the design of durable catalysts for electrocatalytic applications.