Spin-Selective Anti-Perovskite Enables Breakthrough Nitrate-to-Ammonia Electrocatalysis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical nitrate reduction to ammonia is promising for environmental and energy applications.
• Current methods face challenges due to slow proton-coupled electron transfers and side reactions.

Purpose of the Study:

• To introduce a new antiperovskite CuNCo3 catalyst for efficient electrochemical nitrate reduction.
• To investigate the mechanism of nitrate reduction using the novel catalyst.

Main Methods:

• Synthesis and characterization of the antiperovskite CuNCo3 catalyst.
• Electrochemical measurements including Faradaic efficiency and ammonia production rate.
• Operando X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR).

Main Results:

• The CuNCo3 catalyst achieved 100% Faradaic efficiency for ammonia production.
• A high ammonia production rate of 124.6 mg mg_cat^-1 h^-1 was recorded at -0.4 V vs. RHE.
• Operando spectroscopy revealed that spin-selective Co sites are crucial for stabilizing intermediates and lowering hydrogenation barriers.

Conclusions:

• The antiperovskite CuNCo3 framework effectively stabilizes spin-selective Co sites, enhancing nitrate reduction.
• This study demonstrates a robust, earth-abundant catalyst platform for high-performance electrocatalytic ammonia synthesis from nitrate.
• The findings provide mechanistic insights into nitrate reduction pathways.