Atomically Dispersed Nickel Coordinated with Nitrogen on Carbon Nanotubes to Boost Electrochemical CO₂ Reduction

Abstract

Single-atom catalysts (SACs) are being widely developed for the CO2 reduction reaction (CO2RR) because of their remarkable activity and selectivity. However, insufficient CO2RR performance and the poor long-term stability of the SACs remain obstacles to process scale-up. Herein, we explore Ni SACs (Ni-N/NCNT) under practical conditions using a zero-gap CO2 electrolyzer for CO production. We demonstrate that the CO2RR performance of the Ni-N/NCNT results from the suitable Ni–N–C, which enhanced electron transfer and increased CO2 adsorption. Furthermore, we propose a strategy for improving the CO2RR performance and long-term stability by focusing on the membrane electrode assembly (MEA) structure. A maximum Faradaic efficiency of 96.73% (at 2.1 V) and partial current density of 219.49 mA cm–2 (at 2.4 V) for CO production were obtained on the MEA with the Ni-N/NCNT catalyst and the Sustainion (Sust.) membrane. In addition, MEA with Sust. exhibited long-term stability at −100 mA cm–2 for over 60 h.