Electrocatalytic CO₂ reduction (CO₂RR) to alcohols offers a promising strategy for converting waste CO₂ into valuable fuels/chemicals but usually requires large overpotentials. Herein, we report a catalyst comprising unique oxygen-bridged Cu binuclear sites (CuOCu-N₄) with a Cu···Cu distance of 3.0–3.1 Å and concomitant conventional Cu–N₄ mononuclear sites on hierarchical nitrogen-doped carbon nanocages (hNCNCs). The catalyst exhibits a state-of-the-art low overpotential of 0.19 V (versus reversible hydrogen electrode) for ethanol and an outstanding ethanol Faradaic efficiency of 56.3% at an ultralow potential of −0.30 V, with high-stable Cu active-site structures during the CO₂RR as confirmed by operando X-ray adsorption fine structure characterization. Theoretical simulations reveal that CuOCu-N₄ binuclear sites greatly enhance the C–C coupling at low potentials, while Cu-N₄ mononuclear sites and the hNCNC support increase the local CO concentration and ethanol production on CuOCu-N₄. This study provides a convenient approach to advanced Cu binuclear site catalysts for CO₂RR to ethanol with a deep understanding of the mechanism.

中文翻译：

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氧桥铜双核位点可在超低过电势下有效电催化二氧化碳还原为乙醇

电催化CO ₂还原(CO ₂ RR) 为醇提供了一种将废弃CO ₂转化为有价值的燃料/化学品的有前途的策略，但通常需要大的过电势。在此，我们报道了一种催化剂，其包含独特的氧桥铜双核位点（CuOCu-N ₄），其Cu·Cu距离为3.0–3.1 Å，并在分层氮掺杂碳纳米笼上伴随传统的Cu-N ₄单核位点（ hNCNC）。该催化剂对乙醇表现出最先进的0.19 V低过电势（相对于可逆氢电极），在-0.30 V超低电势下具有56.3%的出色乙醇法拉第效率，并具有高稳定的Cu活性位点通过原位X射线吸附精细结构表征证实了CO ₂ RR过程中的结构。理论模拟表明，CuOCu-N ₄双核位点极大地增强了低电势下的C-C耦合，而Cu-N ₄单核位点和hNCNC载体增加了CuOCu-N ₄上的局部CO浓度和乙醇产量。这项研究为先进的Cu双核位催化剂CO ₂ RR转化为乙醇提供了一种便捷的方法，并对其机理有了深入的了解。