Two-dimensional ultrathin nanosheets over mackinawite FeS for efficient electrochemical N2 reduction

Electrocatalytic N2 reduction reaction (NRR) has been considered as a promising and alternative strategy for the synthesis of NH3, which will contribute to the goal of carbon neutrality and sustainability. However, this process often suffers from the barrier for N2 activation and competitive reactions, resulting in poor NH3 yield and low Faraday efficiency (FE). Here, we report a two-dimensional (2D) ultrathin FeS nanosheets with high conductivity through a facile and scalable method under mild condition. The synthesized FeS catalysts can be used as the work electrode in the electrochemical NRR cell with N2-saturated Na2SO4 electrolyte. Such a catalyst shows a NH3 yield of 9.0 µg·h−1·mg−1 (corresponding to 1.47 × 10−4 µmol·s−1·cm−2) and a high FE of 12.4%, which significantly outperformed the other most NRR catalysts. The high catalytic performance of FeS can be attributed to the 2D mackinawite structure, which provides a new insight to explore low-cost and high-performance Fe-based electrocatalysts, as well as accelerates the practical application of the NRR.