Low overpotential reduction of dinitrogen to ammonia in aqueous media

The molecular nitrogen fixation to ammonia is one of the most important processes in chemistry. In this connection, our aim was to realize an electrochemical reaction under extremely mild conditions in an aqueous media for the first time. The reduction of dinitrogen was achieved on a polypyrrole electrode in aqueous 0.1 M Li2SO4/0.03 M H+ solution at 60 bar N2-pressure. The reaction product was only ammonia and the ammonia formation efficiency depends strongly on the applied pressure, temperature, electrode potential, supporting electrolyte, film thickness of polymer electrode, as well as on the amount of proton source added to the electrolyte medium. The maximum yield of NH3 was 53 μM obtained at −0.165 VNHE after 5 h of electrolysis.