Sulfur dots–graphene nanohybrid: a metal-free electrocatalyst for efficient N2-to-NH3 fixation under ambient conditions

Abstract

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 N₂ reduction offers a carbon-neutral process to convert N₂ to NH₃ under ambient conditions, but it requires efficient and stable catalysts to drive the N₂ reduction reaction. Herein, we report that a sulfur dots–graphene nanohybrid acts as a metal-free electrocatalyst for ambient N₂-to-NH₃ conversion with excellent selectivity. When operated in 0.5 M LiClO₄, this electrocatalyst achieves a large NH₃ yield of 28.56 μg h⁻¹ mg_cat.⁻¹ and a high Faradaic efficiency of 7.07% at −0.85 V vs. reversible hydrogen electrode. Notably, it also shows good electrochemical stability.