In situ interface engineered Co/NC derived from ZIF-67 as an efficient electrocatalyst for nitrate reduction to ammonia

Electrocatalytic nitrate (NO3-) reduction to ammonia (NH3) is a promising alternative approach for simultaneous NH3 green synthesis and NO3- contaminants removal. However, the complex eight-electron reaction requires catalysts with superb performance due to the low NH3 selectivity and yield. In this work, the Co nanoparticles decorated N-doped carbon (NC) by in situ interface engineering were prepared by deriving ZIF-67 at 800 ℃ (Co/NC-800) for the selective NH3 synthesis. This catalyst exhibits a remarkable performance and excellent cycle stability, achieving a great NH3 yield of 1352.5 μg h-1 mgcat-1 at -1.7 V vs Ag/AgCl, with a high NH3 selectivity of up to 98.2 %, and a maximum Faradic efficiency of 81.2 % at -1.2 V vs Ag/AgCl. Moreover, DFT calculation results indicate that the interfacial effect between Co nanoparticle and NC could enhance electron transfer, and the composite Co/NC-800 shows a lower adsorption and conversion free energy, which promotes the production of ammonia.