Electrochemical synthesis of ammonia from water and nitrogen: A Fe-mediated approach

Abstract

Operation at mild conditions is essential for electrochemical processes enough to replace the Haber-Bosch process. Current electrochemical methods mainly rely on the synthesis of novel electro-catalysts before the operation of an electrochemical system, which burdens with extra cost, time, and the use of toxic non-green organic solvents. In this study, the zero-valent iron(Fe-0)-mediated synthesis of NH3 was achieved at room temperature, with the active iron prepared in an on-site and continuous way. This on-site approach enabled us to remove the step of cumbersome synthesis of nano-sized electrocatalysts, thereby providing the active surface Fe for nitrogen reduction in eco-friendlier way. When a cell voltage of 4.5 was applied in the two-electrode water-based system, NH3 was found to be synthesized, which was accompanied by the deposition of Fe on the cathode surface. Considering that iron is among the most abundant and cheapest metals, this room-temperature synthesis proof of the concept with solvent-free, in-situ deposition and its utilization as an electrochemical catalyst, once optimized, may offer an economically advantageous option.