Greatly enhanced electrochemical nitrate-to-ammonia conversion over an Fe-doped TiO2 nanoribbon array

Abstract

Electrochemical nitrate (NO₃⁻) reduction is an appealing approach to remove NO₃⁻ contaminants and simultaneously convert them into high value-added ammonia (NH₃), but it requires highly active catalysts with high selectivity. Herein, Fe doping is proposed as an effective strategy to greatly enhance the electrocatalytic NO₃⁻-to-NH₃ conversion over a TiO₂ nanoribbon array supported on a Ti plate. Such an Fe–TiO₂/TP catalyst achieves a large NH₃ yield of up to 940.17 μmol h⁻¹ cm⁻² and a high NH₃ faradaic efficiency of 95.93% under alkaline conditions, superior to those of its undoped TiO₂/TP counterpart (57.47 μmol cm⁻² h⁻¹, 35.77%). Moreover, it also shows excellent electrochemical and structural stability. Theoretical calculations reveal that Fe doping can dramatically improve the electronic conductivity of TiO₂ and optimize the adsorption of reactive species on its surface.