The electrochemical nitrogen reduction reaction (NRR) provides a sustainable alternative to the Haber-Bosch process for ammonia (NH3) production. Transition metal catalysts have poor NRR performance due to the highly competitive hydrogen evolution reaction and the scaling relation between inert dinitrogen (N2) and other reaction intermediates. Single-atom catalysts (SACs) have been
proven to be effective in overcoming these limitations owing to the enhanced active sites and the anomalous quantum size effect.
Inspired by biological rhizobia nitrogen fixation, this proposal, Green Renewable Energy-derived Electrocatalytic Nitrogen reduction reaction that yields NH3 under mild conditions, this project GREEN has focused on the development, characterization and mechanistically understanding of S/P coordinated transition Metal Single sites-doped (Fe, Mo and FeMo) Carbon Matrices (MSCMs) as electrocatalysts for high activity and selectivity NRR.
The specific goals of GREEN and their achievement through its implementation have been as follows:
i) Successfully synthesis of MSCMs electrocatalysts to achieve high performance and selectivity towards NRR;
I have successfully synthesized the MSCMs electrocatalysts to achieve FE (Faradaic Efficiency) of 20% and j (current density) of 10 mA cm-2
ii) Characterize MSCMs to determine their electronic structure, local atomic environment, charge density and affinity with N2 molecules, etc.;
The catalysts were characterized by different techniques: PXRD (X-ray photoelectron spectrometer), FTIR (Fourier transform infrared), HRTEM (high-resolution transmission electron microscopy), SEM (scanning electron microscopy), ICP-OES (Inductively coupled plasma optical emission spectroscopy).
iii) Determine the activity of the MSCMs catalysts and fine-tuning of working conditions and parameters for highly efficient electrocatalytic NRR and the catalytic mechanisms for NRR.
Electrocatalytic test were conducted under different conditions. We optimized the electrolyte (KOH, LiClO4, Kpi), temperature (Room temperature and 40, 60 oC) and pressure (ambient pressure and 4 bars) and also we investigate the ethanol effect during the electrocatalytic process by introducing different volume percentage of ethanol (0%, 5%, 10%, 25% 50% 100%). Furthermore, to study the mechanism, we applied in-situ SEC to track the intermediates and DFT calculations are used for deeper understanding.
