Single-Atom Anchored g-C 3 N 4 Monolayer as Efficient Catalysts for Nitrogen Reduction Reaction.

Electrochemical N 2 reduction reaction (NRR) is a promising approach for NH 3 production under mild conditions. Herein, the catalytic performance of 3d transition metal (TM) atoms anchored on s-triazine-based g-C 3 N 4 (TM@g-C 3 N 4 ) in NRR is systematically investigated by density functional theory (DFT) calculations. Among these TM@g-C 3 N 4 systems, the V@g-C 3 N 4 , Cr@g-C 3 N 4 , Mn@g-C 3 N 4 , Fe@g-C 3 N 4 , and Co@g-C 3 N 4 monolayers have lower ΔG(*NNH) values, especially the V@g-C 3 N 4 monolayer has the lowest limiting potential of -0.60 V and the corresponding limiting-potential steps are *N2+H++e-=*NNH for both alternating and distal mechanisms. For V@g-C 3 N 4 , the transferred charge and spin moment contributed by the anchored V atom activate N 2 molecule. The metal conductivity of V@g-C 3 N 4 provides an effective guarantee for charge transfer between adsorbates and V atom during N 2 reduction reaction. After N 2 adsorption, the p-d orbital hybridization of *N 2 and V atoms can provide or receive electrons for the intermediate products, which makes the reduction process follow acceptance-donation mechanism. The results provide an important reference to design high efficiency single atom catalysts (SACs) for N 2 reduction.