Electrocatalytic Reduction of Nitrogen to Hydrazine Using a Trinuclear Nickel Complex

Abstract

Activation and reduction of N₂ have been a major challenge to chemists and the focus since now has mostly been on the synthesis of NH₃. Alternatively, reduction of N₂ to hydrazine is desirable because hydrazine is an excellent energy vector that can release the stored energy very conveniently without the need for catalysts. To date, only one molecular catalyst has been reported to be able to reduce N₂ to hydrazine chemically. A trinuclear T-shaped nickel thiolate molecular complex has been designed to activate dinitrogen. The electrochemically generated all Ni(I) state of this molecule can reduce N₂ in the presence of PhOH as a proton donor. Hydrazine is detected as the only nitrogen-containing product of the reaction, along with gaseous H₂. The complex reported here is selective for the 4e^-/4H⁺ reduction of nitrogen to hydrazine with a minor overpotential of ∼300 mV.