Cobalt doping of porous graphitic carbon nitride with Co[sbnd]N bonds promotes electrocatalytic N2 fixation under ambient conditions

Abstract

Electrochemical nitrogen reduction reaction (NRR) with nitrogen as the raw material under environmental conditions is regarded as a promising approach to replace the Haber-Bosch process. Nevertheless, identifying an efficient electrocatalyst to improve NRR activity is confronted with challenges. Here, porous graphitic carbon nitride (g-C3N4) was doped with cobalt through hard-template method. The resulting g-C3N4-based electrocatalyst achieved a high ammonia yield rate (49.69 µg·h−1· mgcat.−1) and Faradaic efficiency (32.20%) at a low overpotential of −0.1 V vs. RHE, exceeding those of some previously reported g-C3N4-based electrocatalysts. First-principle calculations revealed that the work function and band gap of catalyst decreased after doping Co, indicating that the introduction of Co promoted the charge transfer. The band center showed an upward shift in Co-doped porous g-C3N4, which may have compensated for the selective adsorption of N2. This work manifested the potential applications of heteroatomic doping in designing NRR catalysts.