The electrocatalytic reduction of nitrate is a sustainable method to produce valuable chemicals such as ammonia, while simultaneously removing industrial pollutants from wastewater. However, the slow dynamics of the necessary proton-coupled electron transfer process generally result in a high barrier and low conversion efficiency.

Ji-Jun Zou, Tianjin University, China, Yong-Chao Zhang, Qingdao University of Science & Technology, China, and colleagues have developed selenium‐deficient FeSe₂/Fe₃O₄ electrocatalysts for the reduction of nitrate to ammonia. The catalysts were synthesized on pure nickel foam via a one-step hydrothermal method at 180 °C, with different selenium contents giving FeSe_1.6/Fe₃O₄, FeSe_1.8/Fe₃O₄, and FeSe₂/Fe₃O₄-type catalysts. The team found that the electrocatalytic nitrate reduction reaction activity of FeSe_1.6/Fe₃O₄ is higher than those of FeSe₂/Fe₃O₄ and FeSe_1.8/Fe₃O₄.

The researchers attribute this high catalytic activity to synergistic effects between the selenium-deficient iron selenide component and the iron oxide component. The Se-deficient iron selenide contributes to nitrate deoxygenation and the subsequent hydrogenation, while the iron oxide promotes the decomposition of water molecules to give protons. Overall, the developed catalyst has potential for use in the treatment of wastewater with high nitrate concentrations.

• Selenium‐Deficient FeSe₂/Fe₃O₄ Electrocatalyst for Nitrate Reduction to Ammonia,
  Yue Du, Haijiao Lu, Jinting Wu, Yalong Zou, Zhen-Feng Huang, Ji-Jun Zou, Tiansheng Mu, Jian Gao, Xiao-Dong Zhu, Yong-Chao Zhang,
  Angew. Chem. Int. Ed. 2024.
  https://doi.org/10.1002/anie.202420903