<i>In Situ</i> Growth of Fe₂O₃ Nanorod Arrays on Carbon Cloth with Rapid Charge Transfer for Efficient Nitrate Electroreduction to Ammonia

Abstract

Electrochemical reduction of nitrate to ammonia (NH₃), a green NH₃ production route upon combining with renewable energy sources, is an appealing and alternative method to the Haber-Bosch process. However, this process not only involves the complicated eight-electron reduction to transform nitrate into various nitrogen products but simultaneously suffers from the competitive hydrogen evolution reaction, challenged by a lack of efficient catalysts. Herein, the <i>in situ</i> growth of Fe₂O₃ nanorod arrays on carbon cloth (Fe₂O₃ NRs/CC) is reported to exhibit a high NH₃ yield rate of 328.17 μmol h^-1 cm^-2 at -0.9 V versus RHE, outperforming most of the reported Fe catalysts. An <i>in situ</i> growth strategy provides massive exposed active sites and a fast electron-transport channel between the carbon cloth and Fe₂O₃, which accelerates the charge-transport rate and facilitates the conversion of nitrate to NH₃. <i>In situ</i> Raman spectroscopy in conjunction with attenuated total reflection Fourier transform infrared spectroscopy reveals the catalytic mechanism of nitrate to NH₃. Our study provides not only an efficient catalyst for NH₃ production but also useful guidelines for the pathways and mechanism of nitrate electroreduction to NH₃.