Modulating Single-Atom Palladium Sites with Copper for Enhanced Ambient Ammonia Electrosynthesis

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrochemical reduction of nitrogen (N₂) to ammonia (NH₃) offers a sustainable alternative for NH₃ production.
• Challenges include poor N₂ adsorption, hindered protonation, and competing hydrogen evolution.
• Single-atom catalysts show promise but require further optimization.

Purpose of the Study:

• To design and synthesize a novel diatomic catalyst for enhanced electrochemical N₂ reduction.
• To investigate the role of diatomic sites in improving N₂ adsorption, protonation, and suppressing hydrogen evolution.
• To evaluate the performance of the new catalyst for ammonia electrosynthesis.

Main Methods:

• Synthesis of diatomic Pd-Cu sites on N-doped carbon.
• Electrochemical characterization including N₂ reduction tests.
• Analysis of catalyst electronic structure and N₂ interaction using density of states and d-2π* coupling.

Main Results:

• The diatomic Pd-Cu catalyst significantly improved N₂ adsorption and protonation compared to single-atom Pd.
• Cu modulation shifted Pd's electronic states and enhanced Pd-N₂ coupling.
• Achieved a high Faradaic efficiency of 24.8±0.8% and NH₃ yield rate of 69.2±2.5 μg h⁻¹ mg⁻¹.
• Suppressed competing hydrogen evolution reaction.

Conclusions:

• Diatomic Pd-Cu sites effectively enhance electrochemical N₂ reduction to NH₃.
• This catalyst design overcomes key limitations in N₂ electrocatalysis.
• Engineering single-atom-based catalysts offers a viable pathway for efficient ammonia electrosynthesis.