Lignin-Derived Ordered Mesoporous Carbon-Supported Bimetallic Cu–Co Nanoparticles for Enrichment and Electroreduction of Nitrate to Ammonia

Owing to the electrocatalytic performance in the nitrate reduction reaction (NO3RR), bimetallic catalysts are emerging reliable candidates for noble metal electrocatalysts to realize the treatment and conversion of nitrate wastewater into valuable ammonia. The bimetallic catalysts can further be economized in the fabrication and enhanced in electrocatalytic performance by using inexpensive biomass-derived mesoporous carbon as supports. Herein, lignin-derived ordered mesoporous carbon (OMC)-supporting bimetallic CuCo nanoparticles (Cu5Co5/OMC) were prepared to enable the nitrate reduction reaction with an ammonia yield rate of 21.05 mg h–1 cm–2, Faradaic efficiency (FENH3) of 96.9% at −0.6 V vs reversible hydrogen electrode (RHE), and a stable FENH3 of above 85% within a wide potential window (−0.2 to −0.8 V vs RHE). An appropriate proportion of copper/cobalt is beneficial to the adsorption and activation of nitrate and progressive hydrogenation through electron redistribution. OMC supports enable uniform dispersion of bimetallic CuCo active sites and good enrichment of reactants. And the density functional theory (DFT) theoretical calculations prove the strong metal–support interaction between CuCo NPs and OMC for boosting the outstanding electrocatalytic performance of Cu5Co5/OMC for NO3RR. The reaction pathway for nitrate reduction was revealed by combination of electrochemical in situ Fourier transform infrared and in situ Raman spectra.