Interstitial carbon induces enriched Cuδ+ sites in Cu2O nanoparticles to facilitate CO2 electroreduction to C2+ products

The electrochemical CO2 reduction reaction (CO2RR) holds significant promise in advancing carbon neutrality. Developing catalysts for the electrochemical CO2RR to multi-carbon (C2+) products (e.g., C2H4) under industrial-level current density is urgently needed and pivotal. Herein, we report the Cu2O nanoparticles doped with interstitial carbon atoms (denoted as C-Cu2O NPs) for the conversion of CO2 to C2+ products. The interstitial carbon promotes the C-Cu2O NPs to possess abundant unsaturated Cu–O bonds, leading to a high-density Cuδ+ (0 < δ <1) species. The obtained C-Cu2O NPs exhibited significant Faradic efficiency (FE) of C2+ products approaching 76.9% and a partial current density reaching 615.2 mA·cm−2 under an industrial-level current density of 800 mA·cm−2. Furthermore, the efficient electrosynthesis of C2H4 achieved an FE of 57.4% with a partial current density of 459.2 mA·cm−2. In situ electrochemical attenuated total reflection Fourier transform infrared spectroscopy and in situ Raman spectroscopy analyses revealed that C-Cu2O NPs stabilized the intermediate *CO and facilitated C–C coupling, leading to increased selectivity towards C2+ products.