Selective CO₂-to-formate electrochemical conversion with core-shell structured Cu₂O/Cu@C composites immobilized on nitrogen-doped graphene sheets

The electrochemical conversion of CO₂into fuels and chemicals attracts worldwide attention for tackling global warming and energy crises. However, the efficiencies and selectivities for targeted products such as formate are still far from satisfactory. Herein, core-shell structured Cu₂O/Cu@C immobilized on nitrogen-doped graphene sheets (Cu₂O/Cu@C/NG) is prepared and used for CO₂reduction. Cu₂O/Cu@C/NG yields higher activity towards formate in terms of a lower onset potential (−0.38 VversusRHE) and higher faradaic efficiency (82.1 ± 1.2%), as well as stable performance over 30 h. The enhancements in selectivity and activity are attributed to the synergistic effects between Cu sites and N doping, simultaneously improving CO₂adsorption and the interfacial charge transfer process. Additionally, N doping restrains hydrogen evolution on the copper sites, leaving more available sites for CO₂reduction. This study provides an efficient strategy to increase the activities of electrocatalysts for CO₂-to-formate electroreduction.