Electrochemical Synthesis of Ammonia from Nitrogen and Water at Ambient Conditions Shreya Mukherjee, Hao Zhang, Gang Wu Vision Long term Objective : Back up of Haber Bosch Process : synthesize ammonia with minimum energy and without using H 2 Major Limitation : Extremely slow kinetics of the process Possible Solution : Develop catalyst that can reduce nitrogen at ambient conditions Background : Approach Acknowledgement . http://www.dtu.dk/nyheder/2017/01/elektrokatalyse-kan-sikre-groen-omstilling?id=fa31e2ea-9427-418e-9437-318dfb497816 Area : Development of Electro Catalysts for synthesizing NH 3 at ambient conditions Focus : Non-Precious Metal Free Catalyst Development Catalyst Synthesis : Optimization : Tuning pyrolysis condition to tune N content Current Status & Future plan Active Site Prediction: • FE of 10 % have been achieved without using any precious metal • Ammonia production rate is comparable and even higher than some precious metal catalyst • Single atom like Ni, Ru on such carbon framework can be synthesized to further increase the activity Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York, Buffalo, New York 14260 Financial supports from the startup fund of University at Buffalo along with U.S. Department of Energy, Advanced Research Projects Agency-Energy (ARPA-e) program are greatly acknowledged. Our Goal Synthesize ammonia without using H 2 at ambient conditions Initial Motivation: Metal nitrides based on DFT Main challenge: Catalyst decomposition Further Modification FeN 4 supported on stable N doped carbon derived from ZIF8 Main Challenge: Evolution of hydrogen Innovation: Development of N doped porous carbon with minimum metal content as catalyst 0 1 2 3 4 0.5 M NaOH 0 Fe Fe-free 20% Fe 1% Fe Fe-free 0.1 M NaOH 20% Fe Production Rate (mol cm -2 h -1 ) 0.1 M KOH 1% Fe Fe-free 0.5 M KOH 500 550 600 650 700 750 800 0.05 0.10 0.15 C-ZIF-1100-1h Ar, 0.1M NaOH N 2 , 0.1M NaOH N 2 , 0.1M KOH Absorbance (a.u) Wavelength (nm) Ar, 0.1M KOH Mukherjee et al. Nano Energy 48 (2018) 217–226 Investigated Fe-N 4 Sites For NRR Activity Activity increased as Fe doping was reduced Highly disordered carbon derived from ZIF - 8 via pyrolysis under inert atmosphere Importance of pyridinic nitrogen vacancy and role of graphitic nitrogen is investigated using DFT studies Potential (V vs. RHE) Activation energy required in Haber Bosch process with triply promoted catalyst is 103 kJ/mol 20 40 60 0 2 4 6 8 Production Rate (mol cm -2 h -1 ) Temperature ( o C) 0.1 M KOH 0.1 M HCl Time (secs) Ar > N 2 N 2 > Ar Ar > N 2