(399f) Metal Nitride-Type Cathode Catalysts for Electrocatalytic Ammonia Production

The development of a less energy-intensive process for ammonia production will be one of the ultimate achievements of the present century [1, 2]. Recent studies have focused on development of new catalysts that operate at lower temperatures and pressures, and alternative processes. Metal nitrides are considered promising ammonia production catalysts due to the presence of lattice nitrogen in their structure which is more active than molecular nitrogen [3]. In addition to catalyst development, alternative reactor designs are also being considered. One of the most promising processes is electrocatalytically-assisted ammonia production using N₂ and H₂O in a solid oxide fuel cell (SOFC)-type reactor coupled with an oxygen ion conductive electrolyte [3, 4].

In the present study, single and bi-metallic nitrides containing Co, Mo and Fe were synthesized via different routes and characterized using XRD, XPS, XAFS, DRIFTS, RAMAN and temperature-programmed desorption (TPD) and reaction (TPRxn) techniques to study their bulk and surface properties. The electrocatalytic activity tests were performed in an SOFC-type reactor in which external electrical energy is provided to electrolyze water and enhance the flux of oxide ions to the anode side. The electrolyte used is yttria-stabilized zirconia (YSZ) sandwiched between two electrodes. Commercially available La_0.8Sr_0.2MnO₃-YSZ is used as the anode, while an in-house developed metal nitride mixed with gold paste is used as the cathode material.

References

1. Amar, I.A., Lan, R., Petit, C.T.G., and Tao, S. J Solid State Electrochem 15, 1845 (2011).
2. Hargreaves, J.S.J. Appl Petrochem Res 4, 3 (2014).
3. Skodra, A., and Stoukides, M. Solid State Ionics 180, 1332 (2009).
4. Marnellos, G., and Stoukides, M. Science 282, 98 (1998).