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Synergistic Cu2O@Ni(OH)2 Core-Shell Electrocatalyst for High-Efficiency Nitrate Reduction to Ammonia.
Zunjie Zhang1, Bingcheng Ge2, Mengran Liu2
1School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, P. R. China.
ACS Applied Materials & Interfaces
|April 23, 2025
Summary
This study introduces a novel copper-based catalyst, Cu₂O@Ni(OH)₂, for efficient electrocatalytic nitrate reduction to ammonia. The catalyst enhances ammonia production by combining copper
Area of Science:
- Electrochemistry
- Materials Science
- Catalysis
Background:
- Nitrate reduction to ammonia (NO₃RR) offers a sustainable route for pollutant remediation and ammonia synthesis.
- Copper-based catalysts excel in NO₃RR due to strong nitrate intermediate binding but suffer from poor water dissociation.
- Inefficient H• generation limits the hydrogenation of nitrate intermediates, hindering overall NO₃RR performance.
Purpose of the Study:
- To design and synthesize a novel shell-core nanocube electrocatalyst, Cu₂O@Ni(OH)₂, for enhanced electrocatalytic nitrate reduction.
- To investigate the synergistic effects between copper oxide and nickel hydroxide for improved NO₃RR performance.
- To elucidate the mechanism of enhanced water dissociation and nitrate hydrogenation.
Main Methods:
- Synthesis of Cu₂O@Ni(OH)₂ shell-core nanocubes via liquid phase reduction, etching, and precipitation.
- Electrochemical characterization including cyclic voltammetry and chronoamperometry.
- Operando Raman and Auger electron spectroscopy to study catalyst transformation during NO₃RR.
- Density functional theory (DFT) calculations and electron paramagnetic resonance (EPR) analysis to understand reaction mechanisms.
Main Results:
- Cu₂O@Ni(OH)₂-3.3% exhibited a high ammonia yield rate of 557.9 μmol h⁻¹ cm⁻² and a Faradaic efficiency of 97.4% at -0.35 V vs. RHE.
- Operando spectroscopy confirmed the reduction of Cu₂O to Cu during the NO₃RR.
- DFT and EPR studies revealed that Ni(OH)₂ facilitates H₂O dissociation, lowering the activation energy barrier and promoting H• generation.
Conclusions:
- The synergistic effect between Cu₂O and Ni(OH)₂ significantly enhances electrocatalytic nitrate reduction to ammonia.
- The developed Cu₂O@Ni(OH)₂ catalyst demonstrates superior performance for sustainable ammonia production.
- This work provides insights into designing efficient electrocatalysts for NO₃RR by addressing water dissociation limitations.
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