Research Projects

Hydrazine (N₂H₄), an energy-rich compound, finds its wide application in the chemical, agricultural, and aerospace industries. The dissociation of N₂H₄ to ammonia (NH₃), N₂, and H₂ generates a huge amount of energy, which makes N₂H₄ a useful chemical as a rocket monopropellant. Additionally, the rapid development of hydrazine fuel cells opens a new area of research, as it can be used in electric vehicles. Consequently, hydrazine is in high market demand. However, the high cost of hydrazine limits its practical application. The existing industrial processes for hydrazine production use NH₃, which is itself very costly. Moreover, these processes require drastic reaction conditions such as high temperature (100˚C) and high pressure (20MPa-200KPa). Thus, it is imperative to find a cost-effective and environment-friendly method for hydrazine production. In this project, we aim to produce hydrazine electrochemically using catalysts inspired by the active site structure of the heme enzyme hydrazine synthase (HzS). It is a naturally occurring enzyme that catalyzes the anaerobic condensation of nitric oxide (NO) and NH₃ to form N₂H₄ through the anammox reaction shown in equation 1. NO + NH₄+ + 2H+ = N₂H₄ + H₂O; [E⁰ = +0.06 V] ----- (1) As reported recently, the crystal structure of HzS contains two heme sites in two out of three subunits. It has been proposed the histidine-coordinated heme center in the active site of the γ subunit catalyzes the reduction of NO to hydroxylamine (NH₂OH; shown in equation 2) while the tyrosine-coordinated heme site in the α subunit catalyzes the condensation reaction between NH₂OH and NH₃ to generate N₂H₄ (shown in equation 3). However, there is a lack of detailed mechanistic studies of this reaction to date. NO + 3H+ + 3e- = NH₂OH ----- (2) NH₂OH + NH₃ = N₂H₄ + H₂O ----- (3) In this project, we will develop molecular catalysts inspired by the structure of the heme center in the α subunit of HzS that can reduce the NH₂OH to N₂H₄. The mechanistic study of the reduction reaction will be performed both chemically and electrochemically. We will use different electrochemical techniques (CV, RDE, RRDE, bulk electrolysis, etc.) to follow the reaction kinetics and understand the mechanism of the reaction. The intermediates will be characterized using Surface Enhanced Resonance Raman Spectroscopy coupled with Rotation Disk Electrochemistry (SERRS-RDE). The N₂H₄ formed after the bulk electrolysis will be analyzed by colorimetric titration. The chemical reduction of NH₂OH to N₂H₄ will be followed using low-temperature UV-visible absorption spectroscopy, and the intermediates involved in the reaction will be characterized using Infrared Spectroscopy (IR) and resonance Raman spectroscopy. This information about the rate-determining step of the reaction and the nature of the intermediate involved in the steady state will be used for further modification of the catalyst for efficient electrochemical production of hydrazine.