Nitrite reduction over Ag nanoarray electrocatalyst for ammonia synthesis.

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Chemistry

Background:

• Electrochemical reduction of nitrite to ammonia is a promising method for ammonia synthesis and nitrogen contaminant removal under mild conditions.
• Efficient and selective catalysts are crucial for this process but remain a challenge.

Purpose of the Study:

• To develop an efficient electrocatalyst for the selective reduction of nitrite to ammonia.
• To investigate the catalytic mechanism of nitrite reduction on silver.

Main Methods:

• Fabrication of a silver (Ag) nanoarray catalyst supported on nickel oxide (NiO) nanosheets on carbon cloth.
• Electrochemical testing in 0.1 M NaOH with 0.1 M nitrite (NO2-).
• Density functional theory (DFT) calculations to elucidate the catalytic mechanism.

Main Results:

• The Ag nanoarray catalyst achieved a maximum ammonia yield of 5,751 μg h⁻¹ cm⁻².
• A high Faradaic efficiency of up to 97.7% for ammonia production was observed.
• DFT calculations provided insights into the catalytic mechanism of nitrite reduction.

Conclusions:

• The Ag nanoarray on NiO nanosheets is an efficient electrocatalyst for selective nitrite to ammonia reduction.
• This catalyst demonstrates potential for simultaneous ammonia synthesis and N-contaminant removal.
• The study provides a mechanistic understanding of the catalytic process.