Selenium-Deficient FeSe/FeO Electrocatalyst for Nitrate Reduction to Ammonia.

Electrocatalytic reduction of NO is a green and sustainable method that not only helps to treat industrial pollutants in wastewater, but also produces valuable chemicals. However, the slow dynamics of the proton-coupled electron transfer process results in a high barrier and low conversion efficiency. In this work, the Se-deficient FeSe/FeO heterojunction was synthesized, which showed excellent electrochemical performance in 0.1 M nitrate reduction reaction, superior to most currently reported catalysts. The high activity of Se-deficient FeSe/FeO is due to the synergistic effect between FeSe and FeO to achieve relay catalytic NO reduction. Among them, the Se-deficient FeSe contributes to NO deoxygenation and subsequent hydrogenation, and FeO promotes HO decomposition to provide H proton, jointly promote NORR. Finally, the online differential electrochemical mass spectra (DEMS), in situ Raman and DFT calculation confirmed the optimal pathway for NORR to NH on Se-deficient FeSe/FeO(100). This strategy of relay catalysis provides a potential way to treat wastewater with high concentration nitrate.