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

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.