A highly active defect engineered Cl-doped carbon catalyst for the N2 reduction reaction

Abstract

eNRR is a promisingly environment-friendly strategy to obtain ammonia under ambient conditions. For metal-based catalysts, the competitive adsorption of H⁺ over N₂ remains the primary hurdle for high ammonia yield and faradaic efficiency. Carbon-based metal-free catalysts attract our attention for the potential of being promising NRR catalysts due to their natural low HER activity. In this study, we prepared a modified Zn-based metal–organic framework (Zn-BTC) decorated with Cl ions by simply adding NaCl in the synthetic process. The existence of Cl ions in the framework contributes to the generation of large pores during thermolysis. Moreover, –Cl and –COCl species were formed in situ and connected with carbon atoms in the defect area. Benefitting from such a structure, this catalyst achieves a high ammonia yield rate of 103.96 μg h⁻¹ mg_cat⁻¹ and a faradaic efficiency of 21.71% at room temperature. Theoretical results also proved that the newly produced –COCl and –Cl functional groups could attract more electrons from adjacent carbon atoms due to their stronger electronegativity, thus improving its affinity towards N₂ while lowering the HER activity as reactive sites.