The determination of reaction mechanism for electrocatalytic CO₂ reduction by experiments is still out of reach on copper catalyst, which limits its advance towards industrial implementation. Here, the Cu/CeO₂ catalyst as paradigm was studied to validate the reaction intermediates and pathway. The Cu/CeO₂ catalysts with different morphologies were synthesized, and it is discovered that the nanorod Cu/CeO₂ catalyst exhibits high selectivity for CO₂-to-CH₄ with the highest turnover frequency for CH₄ production among the samples. Detailed study indicates that the nanorod Cu/CeO₂ possesses the largest electrochemically active surface area, higher proportion of O-vacancy sites, and better capability of CO₂ adsorption and activation. The chemical nature above together contributes to its high activity. Theoretical calculations reveal that the doping of Cu into CeO₂ can significantly lower the reaction energy barrier of *CO₂ →*COOH and change the reaction pathway from *CHOH →*CH₂OH to *CHOH →*CH, effectively improving the catalytic performance for CO₂ electroreduction.

通过实验确定电催化还原CO ₂的反应机理在铜催化剂上仍然遥不可及，这限制了其向工业化应用的进展。在这里，研究了作为范例的 Cu/CeO ₂催化剂以验证反应中间体和途径。合成了不同形貌的Cu/CeO ₂催化剂，发现纳米棒Cu/CeO ₂催化剂对CO ₂至CH ₄表现出高选择性，样品中CH ₄生成的周转频率最高。详细研究表明，纳米棒 Cu/CeO ₂具有最大的电化学活性表面积，更高比例的O空位，以及更好的CO ₂吸附和活化能力。上述化学性质共同促成了其高活性。理论计算表明，在CeO _{2 中}掺杂Cu可以显着降低*CO ₂ →*COOH的反应能垒，将反应路径由*CHOH →*CH ₂ OH转变为*CHOH →*CH，有效提高催化性能用于CO ₂电还原。