Nitrogen (N), Phosphorus (P)-Codoped Porous Carbon as a Metal-Free Electrocatalyst for N₂ Reduction under Ambient Conditions

Abstract

The electrocatalytic conversion of nitrogen gas at ambient conditions represents a novel approach for ammonia synthesis to the sustainable society. It is critical to understand the detailed pathways and mechanisms of this promising process to develop a highly efficient catalyst. Herein, the N, P co-doping carbon (NP-C-MOF-5) catalyst was prepared for electrocatalytic N₂ reduction in acid electrolytes under ambient temperatures and pressures. Experimental results showed that there are two products including NH₃ and N₂H₄·H₂O on the NP-C-MOF-5 cathode at -0.1 V versus RHE with the yield of 1.08 and 5.77 × 10^-4 μg h^-1 mg_cat.^-1, respectively. Moreover, an electrocatalytic pathway on NP-C-MOF-5 was investigated by the electrochemical in situ Fourier transform infrared technique. The results confirmed the formation of N₂H _y (1 ≤ y ≤ 4) intermediates on NP-C-MOF-5 cathode surfaces, suggesting an associative pathway for the N₂ reduction reaction.