Electrocatalytic nitrate (NO₃⁻ ) reduction reaction (NO₃⁻ RR) is a promising avenue for wastewater treatment and value-added ammonia (NH₃) generation. Herein, cobalt manganese spinel nanoparticles embedded in multichannel carbon fibers (CoMn₂O₄/NC) to obtain optimal NH₃ Faradaic efficiency is 92.4% with a yield rate of 144.5 mmol h⁻¹ g⁻¹ at − 0.7 V versus reversible hydrogen electrode (vs. RHE). The interfacial between CoMn₂O₄ and NC induces the 3d orbital electrons of Co and Mn in less localized states, which promotes *NH₃ desorption. Electrochemical in situ Raman spectra and online differential electrochemical mass spectrometry (DEMS) identified the intermediates and products. The theoretical calculation demonstrates that the existence of NC could reduce the free energy difference of the rate-determining step (RDS, 0.42 eV) of NO₃⁻ RR, suppressing hydrogen evolution reaction (HER) by enhancing the interaction of *H. Coupled benzyl alcohol oxidation reaction (BOR) with NO₂⁻ RR to obtain lower reduction voltage and high value-added anode products.