Fe-doped CuO embedded in carbon nanosheets for efficient and selective nitrate electroreduction to ammonia

Abstract

The nitrate electroreduction reaction (NO₃⁻RR) provides a low-carbon and environmentally friendly strategy for ammonia production. Here, a sustainable method for synthesizing carbon nanosheets is developed by assembling biomass molecules on a boric acid template, followed by thermal annealing. During this process, the introduction of Fe³⁺ and Cu²⁺ ions enables the formation of Fe-doped CuO nanoparticles embedded in carbon nanosheets (Fe–CuO/C). The Fe–CuO/C shows high activity for the NO₃⁻RR resulting in a low potential of 0.089 and −0.192 V vs. RHE at −10 and −50 mA cm⁻², with high ammonia yield and faraday efficiency. Theoretical calculations indicate that the *NO to *NOH step is the rate-determining step during the NO₃⁻RR. The doping of Fe effectively reduces the energy barrier of this step.