Selenium-Deficient FeSe₂/Fe₃O₄ Electrocatalyst for Nitrate Reduction to Ammonia

Area of Science:

• Materials Science
• Electrochemistry
• Environmental Science

Background:

• Electrocatalytic reduction of nitrate (NO₃^-) is a sustainable method for wastewater treatment and chemical production.
• The proton-coupled electron transfer process in nitrate reduction faces challenges like high energy barriers and low efficiency.

Purpose of the Study:

• To synthesize a Se-deficient FeSe₂/Fe₃O₄ heterojunction for enhanced electrocatalytic nitrate reduction.
• To investigate the synergistic effects and reaction mechanisms of the novel catalyst.

Main Methods:

• Synthesis of Se-deficient FeSe₂/Fe₃O₄ heterojunction.
• Electrochemical evaluation of nitrate reduction reaction (NO₃RR) performance.
• In-situ characterization using differential electrochemical mass spectrometry (DEMS) and Raman spectroscopy.
• Density Functional Theory (DFT) calculations to elucidate the reaction pathway.

Main Results:

• The Se-deficient FeSe₂/Fe₃O₄ heterojunction exhibited superior electrochemical performance in NO₃RR compared to existing catalysts.
• Synergistic effects between FeSe₂ and Fe₃O₄ were observed, facilitating relay catalysis for nitrate reduction.
• Se-deficient FeSe₂ aids in NO₃^- deoxygenation and hydrogenation, while Fe₃O₄ promotes H₂O decomposition for proton supply.
• The optimal pathway for NO₃RR to ammonia (NH₃) on Se-deficient FeSe₂/Fe₃O₄(100) was confirmed.

Conclusions:

• The Se-deficient FeSe₂/Fe₃O₄ heterojunction demonstrates significant potential as an efficient electrocatalyst for nitrate reduction.
• The relay catalysis strategy offers a promising approach for treating high-concentration nitrate wastewater.
• This work provides insights into designing advanced catalysts for environmental remediation and chemical synthesis.