(513fq) High Temperature Electrochemical Nitrogen Reduction on Solid Oxide Supported Catalysts

Electrochemical ammonia synthesis offers an alternative to the energy intensive Haber-Bosch process that would use electrochemical potential instead of high pressure and temperature to drive the reaction. Unfortunately, the highest yields achieved electrochemically are orders of magnitude lower than necessary to be industrially relevant [1]. This is often attributed to the dominance of the competing hydrogen evolution reaction (HER) at the reducing potentials necessary for the nitrogen reduction reaction (NRR) to take place. Most electrochemical NRR experiments are run at ambient pressures and temperatures in liquid electrolytes, however, the kinetics are extremely challenging at these conditions. A less frequently used experimental method for electrochemical NRR is to perform the reaction at higher temperatures using a solid electrolyte for proton conduction [2]. High temperatures offer faster kinetics and allow the use of a solid electrolyte, which may reduce the access of protons to the active site for NRR. One computational study of ambient temperature electrochemical NRR on metals suggested that this reduced proton concentration could improve selectivity [3]. Using density functional theory (DFT) and micro-kinetic modeling, we show the combined effect that high temperature and limited proton concentration can have on the electrochemical NRR for different catalysts supported on proton conducting BaZrO₃.

References:

1. Soloveichik, G. Catal. 2, 377–380 (2019).
2. Kyriakou, V., Garagounis, I., Vourros, A., Vasileiou, E. & Stoukides, M. Joule 4, 142–158 (2020).
3. Singh, A. R. et al. ACS Catal. 9, 8316–8324 (2019).