Precursor Engineering of Low-Coordinated Oxygen-Bearing Cu Electrocatalysts for Selective CO₂ Reduction toward Multicarbon Products

To improve the selectivity toward multicarbon (C₂₊) products for electrochemical CO₂ reduction, herein, low-coordinated oxygen-bearing Cu electrocatalysts were obtained from copper(II) benzene-1,3,5-tricarboxylate as precursors through a two-step process following hydrogen peroxide (H₂O₂)-assisted cathodic electrodeposition and in situ electroreduction. With defects such as O atoms and vacancies introduced during electrochemical reconstruction, the oxygen-bearing Cu electrocatalysts with a lowered Cu–Cu coordination is evidenced to favor the selective eCO₂RR toward C₂₊ products. As a result, a high selectivity of 80.5% toward C₂₊ products is achieved at –1.3 V vs reversible hydrogen electrodes. Impressively, the low-coordinated oxygen-bearing Cu electrocatalysts could stably and selectively generate C₂₊ products with faradaic efficiency reaching ∼77.5% at an industrial-level current density of –200 mA cm^–2 in a flow cell. In situ spectral characterizations and theoretical calculations reveal that the lowered Cu–Cu coordination and oxygen modification could upshift the energy level of the d-band center (E_d) for active Cu sites, which would enhance the surface binding of *CO and *COH intermediates and facilitate the formation of *OCCOH intermediates by following the *CO + *CO → *CO + *COH → *OCCOH pathway, which finally enables the highly selective generation of C₂₊ products.