NH2-MIL-88B-Fe for electrocatalytic N2 fixation to NH3 with high Faradaic efficiency under ambient conditions in neutral electrolyte

The global NH3 production is dominated by Haber-Bosch process, requiring high temperature and pressure. Electrochemical N-2 reduction reaction (NRR) under ambient conditions is a greener path for artificial N-2 fixation to NH3 but calling for efficient catalyst to increase activity and selectivity. Herein, we report the iron-based metal-organic frameworks (MOFs), i.e., MIL-88B-Fe and amine-functionalized MIL-88B-Fe (NH2-MIL-88B-Fe) as efficient catalysts for electrochemical NRR under ambient temperature and pressure in neutral electrolyte. NH2-MIL-88B-Fe shows higher NH3 yield rate of 1.205 x 10(-10) mol s(-1) cm(-2) than MIL-88B-Fe (3.575 x 10(-11) mol s(-1) cm(-2)). Furthermore, NH2-MIL-88B-Fe exhibits the highest Faradaic efficiency of 12.45% at 0.05 V versus RHE. The control experiments prove that NH3 is produced through electrocatalytic NRR. This work may trigger the interest of using MOFs as highly efficient catalysts for electrochemical NH3 production.