P-Modified Single-Atom Cu Catalyst Boosting Electrocatalytic Performance of NO3- Reduction to NH3

Electrochemical conversion of NO3- to NH3 production is of great environmental significance for water pollution treatment and can artificially close the nitrogen cycle. However, direct nine protons and eight electrons transfer lead to low Faraday efficiency (FE) and yield. Herein, the single copper site immobilized on N,P co-doped carbon substrates (Cu-N-4/P) was prepared for efficient NO3--to-NH3 conversion. Benefiting from the electronic redistribution of the Cu site induced by the introduction of the less electronegative element P, the Cu-N-4/P catalyst exhibited a high Faraday efficiency of FE (95.89 %) for NH3 product formation at a potential of -0.6 V vs. RHE and 100 % conversion of NO3--N was achieved after 5 hours of electrolysis. Density functional theory (DFT) explains the effective operation mechanism that P doping can promote the spontaneous hydrogenation of *NO to form *NOH, thus promoting the formation of NH3 from NO3- reduction reaction. The heteroatom doping strategy mentioned proposes a new approach for promoting NO3--to-NH3 conversion at atomic level catalytic sites.