Hierarchical Cross‐Linked Carbon Aerogels with Transition Metal‐Nitrogen Sites for Highly Efficient Industrial‐Level CO2 Electroreduction

Abstract Developing highly efficient carbon aerogels (CA) electrocatalysts based on transition metal‐nitrogen sites is critical for the CO 2 electroreduction reaction (CO 2 RR). However, simultaneously achieving a high current density and high Faradaic efficiency (FE) still remains a big challenge. Herein, a series of unique 3D hierarchical cross‐linked nanostructured CA with metal‐nitrogen sites (MN, M = Ni, Fe, Co, Mn, Cu) is developed for efficient CO 2 RR. An optimal CA/N‐Ni aerogel, featured with unique hierarchical porous structure and highly exposed M‐N sites, exhibits an unusual CO 2 RR activity with a CO FE of 98% at −0.8 V. Notably, an industrial current density of 300 mA cm −2 with a high FE of 91% is achieved on CA/N‐Ni aerogel in a flow‐cell reactor, which outperforms almost all previously reported M‐N/carbon based catalysts. The CO 2 RR activity of different CA/N‐M aerogels can be arranged as Ni, Fe, Co, Mn, and Cu from high to low. In situ spectroelectrochemistry analyses validate that the rate‐determining step in the CO 2 RR is the formation of *COOH intermediate. A ZnCO 2 battery is further assembled with CA/N‐Ni as the cathode, which shows a maximum power density of 0.5 mW cm −2 and a superior rechargeable stability.