Atomic-scale Cu-Zn synergy directs asymmetric C-C coupling for ethanol-selective CO2 electroreduction

초록

Selective electrochemical conversion of CO2 to ethanol remains a major barrier to scalable ethanol production and effective carbon utilization. Here we report a CuZn single-atom dimer on N-doped carbon (CuZn-SAD-NC) that exhibits a significant single-product Faraday efficiency (FE) of 69% and remains stable without degradation for 55 h in a two-electrode system. XANES analysis reveals that Zn electronically modulates the oxidation state of Cu through direct bonding, promoting *CO protonation on Cu to form *COH and enabling asymmetric CO-*COH coupling, as further supported by in situ Raman and DFT calculations. The resulting *OCHCH2 intermediate subsequently undergoes protonation to yield ethanol, facilitated by the enhanced local CO availability provided by Zn. Control Experiments show that the FE of EtOH was highly sensitive to the dispersion of CuZn atoms in CuZn-SAD-NC, with a maintained minimal intermetallic distance and decreased significantly when clusters became the predominant species in CuNP-ZnSA-NC. This work establishes a foundational approach for enhancing product selectivity by precisely tuning the metal-metal distance and oxidation states of targeted metals to stabilize specific reaction intermediates. © 2026 Elsevier B.V.

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