Efficient electrocatalytic nitric oxide reduction to ammonia using manganese spinel oxides

Abstract

The 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 carbon fiber-supported CoMn₂O₄ spinel oxide nanoparticles (CoMn₂O₄/C) for the electrocatalytic NORR to NH₃. CoMn₂O₄/C delivers a 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 the HER. This work provides a reference for the rational design of electrocatalysts for boosting NH₃ production.