Shear-Strained Pd Single-Atom Electrocatalysts for Nitrate Reduction to Ammonia.

Area of Science:

• Catalysis
• Electrochemistry
• Materials Science

Background:

• Electrochemical nitrate reduction (NitRR) is a promising low-carbon ammonia synthesis method.
• Copper-based catalysts are effective but struggle with active hydrogen formation, leading to by-products.
• Improving active hydrogen generation is key to efficient nitrate-to-ammonia conversion.

Purpose of the Study:

• To develop a novel catalyst for enhanced electrochemical nitrate reduction to ammonia.
• To investigate the role of single palladium atoms on copper oxide dislocations in promoting ammonia synthesis.
• To optimize catalyst performance for higher ammonia yield and Faraday efficiency.

Main Methods:

• Preparation of Pd single atoms on dislocation-induced CuO unsaturated bonds (Pd-CuO) via low-temperature treatment.
• Electrochemical characterization, including in situ measurements.
• Density Functional Theory (DFT) calculations to understand reaction mechanisms.

Main Results:

• The Pd-CuO catalyst achieved an ammonia yield of 4.2 mol·g_cat^-1·h^-1.
• A high Faraday efficiency of 90% for ammonia production was observed at -0.5 V vs. RHE.
• Dynamic effects and shear stress on Pd single atoms promoted active hydrogen production and reduced reaction barriers.

Conclusions:

• The Pd-CuO catalyst effectively enhances electrochemical nitrate reduction to ammonia.
• Single Pd atoms on CuO dislocations, under dynamic shear stress, significantly improve catalytic activity.
• This approach offers a pathway to more efficient and selective green ammonia synthesis.