Bi1‐CuCo2O4 Hollow Carbon Nanofibers Boosts NH3 Production from Electrocatalytic Nitrate Reduction

Abstract

AbstractAmmonia, as a high‐energy‐density carrier for hydrogen storage, is in great demand worldwide. Electrocatalytic nitrate reduction reaction (NO3RR) provides a green NH3 production process. However, the complex reaction pathways for NO3RR to NH3 and the difficulty in controlling intermediate products limit the reduction process. Herein, by incorporating atomic‐level bismuth (Bi) into CuCo2O4 hollow carbon nanofibers, the catalytic activity of the electrocatalyst for NO3RR is enhanced. The maximum Faradaic efficiency of Bi1‐CuCo2O4 is 95.53%, with an NH3 yield of 448.74 µmol h−1 cm−2 at −0.8 V versus RHE. Density Functional Theory calculations show that the presence of Bi lowers the reaction barrier for the hydrogenation step from *NO2 to *NO2H, while promoting mass transfer on the release of *NH3 and the reactivation of surface‐active sites. Differential charge density calculations also show that after Bi doping, the charge supplied by the catalyst to NO3− increases from 0.62 to 0.72 e‐, thus reasoned for enhanced NO3RR activity. The established nitrate‐Zn battery shows an energy density of 2.81 mW cm−2, thus implying the potential application.