High yields of C₂ products through electrocatalytic CO₂ reduction (eCO₂R) can only be obtained using Cu-based catalysts. Here, we adopt the generalized frontier molecular orbital (MO) theory based on first-principles calculations to identify the origin of this unique property of Cu. We use the grand canonical ensemble (or fixed potential) approach to ensure that the calculated Fermi level, which serves as the frontier orbital of the metal catalyst, accurately represents the applied electrode potentials. We determine that the key intermediate OCCO assumes a U-shape configuration with the two C atoms bonded to the Cu substrate. We identify the frontier MOs that are involved in the C–C coupling. The good alignment of the Fermi level of Cu with these frontier MOs is perceived to account for the excellent catalytic performance of Cu for C–C coupling. It is expected that these new insights could provide useful guidance in tuning Cu-based catalysts as well as designing non-Cu catalysts toward high-efficiency eCO₂R.

中文翻译：

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铜作为电催化 CO2 还原中 C-C 偶联的独特催化剂的起源

只有使用铜基催化剂才能通过电催化CO ₂还原(eCO ₂ R) 获得高产率的C ₂产品。在这里，我们采用基于第一性原理计算的广义前沿分子轨道（MO）理论来确定Cu这种独特性质的起源。我们使用大正则系综（或固定电势）方法来确保计算出的费米能级（作为金属催化剂的前沿轨道）准确地代表所施加的电极电势。我们确定关键中间体 OCCO 呈现 U 形构型，其中两个 C 原子键合到铜基板上。我们确定了参与 C-C 耦合的前沿 MO。 Cu 的费米能​​级与这些前沿 MO 的良好对齐被认为是 Cu 对 C-C 偶联具有优异催化性能的原因。预计这些新见解可以为调整铜基催化剂以及设计非铜催化剂以实现高效 eCO ₂ R提供有用的指导。