Efficient Electrocatalytic Nitric Oxide Reduction to Ammonia by Manganese Spinel Oxides

Abstract

Electrocatalytic nitric oxide (NO) reduction reaction (NORR) driven by renewable electricity is a sustainable route for air pollution treatment and ammonia (NH3) synthesis. Herein, we report a carbon fiber-supported CoMn2O4 spinel oxide nanoparticles (CoMn2O4/C) for electrocatalytic NORR to NH3. The CoMn2O4/C delivers the maximum NH3 Faradaic efficiency of 89.3% with a yield rate of 497.6 mmol h−1 g−1 at −0.7 V versus a reversible hydrogen electrode (vs. RHE), which is significantly better than that of CoMn2O4 (325 mmol h−1 g−1, 86.3%) under similar conditions. In situ Raman and theoretical calculations confirmed that the CoMn2O4/C composite catalyst contributed to optimizing the adsorption behavior of protons and NO on the CoMn2O4 surface. The conductive carbon support coupling significantly enhances the NO adsorption energy of CoMn2O4 and decreases the free energy change of the potential determining step (PDS) to *NHO, effectively promoting *NH3 desorption and inhibiting HER. This work provides a reference for the rational design of electrocatalysts for boosting NH3 production.