Transition-Metal-Doped Hexagonal Boron Nitride for Efficient and Selective Nitrate-to-Ammonia Electrocatalysis:...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry
• Catalysis

Background:

• Nitrate contamination poses a significant threat to water resources, necessitating effective remediation strategies.
• Electrochemical nitrate reduction reaction (NO₃RR) offers a promising pathway for both nitrate removal and ammonia (NH₃) production.
• Developing efficient and selective electrocatalysts is crucial for advancing NO₃RR technology.

Purpose of the Study:

• To computationally screen transition-metal-doped hexagonal boron nitride (TM@h-BN) monolayers as potential single-atom catalysts for NO₃RR.
• To identify catalysts with low overpotentials and high selectivity for ammonia synthesis.
• To establish design principles for next-generation electrocatalysts for sustainable ammonia production.

Main Methods:

• First-principles density functional theory (DFT) calculations were performed to evaluate the catalytic performance of various TM@h-BN systems.
• Key reaction parameters, including limiting potentials and binding energies, were systematically analyzed.
• A SISSO-based machine learning framework was integrated to identify descriptor-performance relationships.

Main Results:

• Fe@h-BN and Ir@h-BN were identified as highly promising catalysts, with limiting potentials of -0.45 V and -0.31 V, respectively.
• These catalysts demonstrate balanced interaction with nitrate, efficient ammonia production, and suppressed hydrogen evolution reaction (HER).
• High selectivity towards NH₃ was observed due to elevated byproduct formation potentials.
• Machine learning identified key descriptors and established a predictive equation for NO₃RR catalyst performance.

Conclusions:

• Fe@h-BN and Ir@h-BN represent advanced single-atom catalysts for efficient electrochemical nitrate reduction to ammonia.
• The study provides valuable mechanistic insights and a transferable design principle for developing novel electrocatalysts.
• This work contributes to sustainable ammonia production and effective water resource management.