In-Situ Exsolving Silver Nano-islands on High-Entropy Perovskites for Energy-Efficient Coupled Nitrate Reduction and...

Area of Science:

• Electrochemistry
• Materials Science
• Environmental Science

Background:

• Electrochemical nitrate reduction to ammonia (NO3RR) is key for nitrogen recycling but faces challenges like complex kinetics and hydrogen evolution.
• Coupling NO3RR with sulfide oxidation reaction (SOR) offers an energy-efficient route for dual-pollutant remediation and valuable product generation.

Purpose of the Study:

• To develop a tandem electrocatalyst for efficient electrochemical nitrate reduction to ammonia coupled with sulfide oxidation.
• To investigate the synergistic interaction between exsolved silver nano-islands and a high-entropy perovskite oxide matrix.

Main Methods:

• In situ exsolution strategy to synthesize Ag nano-islands on a high-entropy perovskite oxide (Ag-LaSrAgFeCoO_x).
• Electrochemical characterization to evaluate NO3RR and SOR performance.
• In situ characterization and theoretical calculations to elucidate the catalytic mechanism.

Main Results:

• The Ag-LaSrAgFeCoO_x catalyst achieved a high NH4+ Faradaic efficiency of 97.6% and a yield rate of 0.35 mmol h-1 cm-2.
• A relay catalytic mechanism was identified, with Ag sites activating nitrate and the perovskite matrix facilitating intermediate hydrogenation and ammonia desorption.
• The bifunctional catalyst enabled energy-efficient NO3RR||SOR coupling, yielding a positive open-circuit potential of 557 mV and stable co-production of ammonia and sulfur.

Conclusions:

• High-entropy materials serve as a powerful platform for designing tandem electrocatalysts for complex coupled reactions.
• The developed catalyst demonstrates a promising approach for simultaneous nitrogen recycling and dual-pollutant remediation.
• The synergistic interaction between exsolved Ag and the oxygen-vacancy-rich perovskite matrix is crucial for efficient catalysis.