Synergistic enhancement of electrocatalytic CO₂ reduction to C₂ oxygenates at nitrogen-doped nanodiamonds/Cu interface

To date, effective control over the electrochemical reduction of CO₂ to multicarbon products (C ≥ 2) has been very challenging. Here, we report a design principle for the creation of a selective yet robust catalytic interface for heterogeneous electrocatalysts in the reduction of CO₂ to C₂ oxygenates, demonstrated by rational tuning of an assembly of nitrogen-doped nanodiamonds and copper nanoparticles. The catalyst exhibits a Faradaic efficiency of ~63% towards C₂ oxygenates at applied potentials of only −0.5 V versus reversible hydrogen electrode. Moreover, this catalyst shows an unprecedented persistent catalytic performance up to 120 h, with steady current and only 19% activity decay. Density functional theory calculations show that CO binding is strengthened at the copper/nanodiamond interface, suppressing CO desorption and promoting C₂ production by lowering the apparent barrier for CO dimerization. The inherent compositional and electronic tunability of the catalyst assembly offers an unrivalled degree of control over the catalytic interface, and thereby the reaction energetics and kinetics.