Metal-free C5N2 doped with a boron atom as an efficient electrocatalyst for the nitrogen reduction reaction

Electrochemical nitrogen reduction reactions (NRR) under ambient conditions are a promising and attractive way to ammonia (NH3) synthesis. It is significant to develop efficient and low-cost electrocatalysts for nitrogen reduction. Herein, an investigation of single B atom doped C5N2 as a metal-free electrocatalyst for NRR was carried out using density functional theory (DFT) calculations. The results show that the boron atom is preferentially doped into the interstitial site of C5N2. The formed B-interstitial (B-int)-doped C5N2 sufficiently activates the nitrogen (N-2) molecule through the "acceptance-donation" process. In particular, N-2 can be effectively reduced via an alternating mechanism with a low overpotential (0.38 V). Thus, by carefully controlling the doping sites, the B-doped C5N2 can be an ideal candidate for an efficient NRR, which may provide a new idea in the design of NH3 synthesis catalysts.