▎ 摘　　要

NH3 is an important chemical with a wide range of applications, but its synthesis mainly relies upon the harsh Haber-Bosch process with huge CO2 emission. Electrochemical N-2 reduction offers a carbon-neutral process to convert N-2 to NH3 under ambient conditions, but it requires efficient and stable catalysts to drive the N-2 reduction reaction. Herein, we report that a sulfur dots-graphene nanohybrid acts as a metal-free electrocatalyst for ambient N-2(-) to -NH3 conversion with excellent selectivity. When operated in 0.5 M LiClO4, this electrocatalyst achieves a large NH3 yield of 28.56 lg h(-1) mgcat.(-1) and a high Faradaic efficiency of 7.07% at similar to 0.85 V vs. reversible hydrogen electrode. Notably, it also shows good electrochemical stability.