Stabilizing highly active atomically dispersed NiN_(4)Cl sites by Cl-doping for CO_(2)electroreduction

Nickel-nitrogen-carbon single-atom catalysts have attracted widespread interest for CO_(2)electroreduction but they suffer from poor stability.Herein,we report on the preparation of Cl-and N-doped porous carbon nanosheets with atomically dispersed NiN_(4)Cl active sites(NiN_(4)Cl-ClNC)through a molten-salt-assisted pyrolysis strategy.The optimized NiN_(4)Cl-ClNC catalyst delivers exceptional CO_(2)conversion activity with outstanding stability for over 220 h at−0.7 V versus RHE and a high CO Faradaic efficiency of 98.7%at a CO partial current density of 12.4 mA cm^(−2).Moreover,NiN_(4)Cl-ClNC displays a remarkable CO partial current density of approximately 349.4 mA cm^(−2)in flow-cell,meeting the requirements of industrial applications.Operando attenuated total reflectance surface-enhanced infrared absorption spectroscopy and density functional theory calculations are used to understand the outstanding activity and stability.Results reveal that the introduced axial Ni-Cl bond on the Ni center and Cl─C bond on the carbon support synergetically induce electronic delocalization,which not only stabilizes Ni against leaching but also facilitates the formation of the COOH*intermediate that is found to be the rate-determining step.