Direct Eight-Electron N2O Electroreduction to NH3 Enabled by an Fe Double-Atom Catalyst.

Abstract

N₂O is a dominant atmosphere pollutant, causing ozone depletion and global warming. Currently, electrochemical reduction of N₂O has gained increasing attention to remove N₂O, but its product is worthless N₂. Here, we propose a direct eight-electron (8e) pathway to electrochemically convert N₂O into NH₃. As a proof of concept, using density functional theory calculation, an Fe₂ double-atom catalyst (DAC) anchored by N-doped porous graphene (Fe₂@NG) was screened out to be the most active and selective catalyst for N₂O electroreduction toward NH₃ via the novel 8e pathway, which benefits from the unique bent N₂O adsorption configuration. Guided by theoretical prediction, Fe₂@NG DAC was fabricated experimentally, and it can achieve a high N₂O-to-NH₃ Faradaic efficiency of 77.8% with a large NH₃ yield rate of 2.9 mg h^-1 cm^-2 at -0.6 V vs RHE in a neutral electrolyte. Our study offers a feasible strategy to synthesize NH₃ from pollutant N₂O with simultaneous N₂O removal.