Oxygen-deficient NiCo2O4 porous nanowire for superior electrosynthesis of ammonia coupling with valorization of ethylene glycol

Abstract

Electrocatalytic nitrate reduction (NO3RR) is emerging as promising pathway for ammonia (NH3) synthesis. The development of NO3RR-based coupling systems are vital for the energy-saving electrosynthesis of high-added chemicals, but the efficient bifunctional electrocatalysts are lacking. Herein, we take oxygen-deficient NiCo2O4 (Vo-NiCo2O4) porous nanowire as a conceptual example to study its potential application in the co-production of NH3 and formate by ethylene glycol oxidation reaction (EGOR) assisted NO3RR technology. Benefiting from the unique porous structure, abundant oxygen vacancies, active dual metal centers, and the improved reaction kinetics, the Vo-NiCo2O4/NF displays excellent bifunctional performance and can be applied for NO3RR||EGOR electrolyzer by the membrane electrode assembly (MEA). Specifically, the electrolyzer achieves a high current density of 100 mA cm−2 a low voltage of 1.53 V and delivers high Faradaic efficiency of formate (over 94.2 %) and NH3 (over 96.3 %) at 1.4 V, along with superior catalytic stability over 120 h. In-situ characterizations confirm the main active Co-O species and the formation of formate for EGOR, as well as the NHO pathway with the appearance of –NH2OH key intermediate for NO3RR. Our work offers a promising strategy for co-upcycling production of valuable chemicals.