Electrocatalytic upcycling of nitrate and hydrogen sulfide via a nitrogen-doped carbon nanotubes encapsulated iron carbide electrode

To achieve the efficient electrocatalytic upgrading of nitrate (NO3−) and hydrogen sulfide (H2S) to value-added ammonia (NH3) and sulfur (S) from wastewater, herein, we report a remarkable nitrogen-doped carbon nanotubes encapsulated iron carbide array electrode (Fe3[email protected]/IF) as both cathode and anode for the efficient electrocatalytic reduction of NO3− to NH3 and oxidation of H2S to S, respectively. Both experimental and theoretical calculation confirm the high activity of Fe3[email protected]/IF. A maximal NH3 faradaic efficiency of ~97.9% with the yield rate of 0.922 mg h−1 cm−2 at − 1.1 V vs. SCE and the S yield rate of 33.76 mg h−1 cm−2 at the current density of 100 mA cm−2 can be achieved. In addition, a flow cell is employed with a multifunctional Fe3[email protected]/IF electrode with channels made by laser to maintains excellent stability for continuous upcycling NO3− and H2S to produce NH3 and S, which demonstrates its massive potential for practical application.