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

Area of Science:

• Electrochemistry
• Catalysis
• Environmental Science

Background:

• Nitrous oxide (N₂O) is a potent greenhouse gas and ozone-depleting substance.
• Current N₂O electrochemical reduction yields nitrogen (N₂), a low-value product.
• Developing efficient N₂O conversion methods is crucial for environmental remediation and resource synthesis.

Purpose of the Study:

• To propose and validate a direct eight-electron (8e) electrochemical pathway for converting N₂O into ammonia (NH₃).
• To identify and experimentally verify a highly active and selective catalyst for N₂O electroreduction to NH₃.
• To demonstrate simultaneous N₂O removal and NH₃ synthesis from a pollutant.

Main Methods:

• Density functional theory (DFT) calculations to screen catalysts.
• Fabrication of a proposed Fe₂ double-atom catalyst (DAC) anchored by N-doped porous graphene (Fe₂@NG).
• Electrochemical testing in a neutral electrolyte to evaluate catalyst performance.

Main Results:

• DFT identified Fe₂@NG as an optimal catalyst for the 8e N₂O reduction pathway via a bent N₂O adsorption configuration.
• Experimental synthesis of Fe₂@NG DAC achieved a 77.8% Faradaic efficiency for NH₃ production.
• A high NH₃ yield rate of 2.9 mg h⁻¹ cm⁻² was obtained at -0.6 V vs RHE.

Conclusions:

• The Fe₂@NG DAC effectively catalyzes the direct 8e electroreduction of N₂O to NH₃.
• This study presents a viable strategy for synthesizing NH₃ from the pollutant N₂O.
• The developed method contributes to simultaneous environmental remediation and valuable chemical production.