Electrochemical promotion of ammonia synthesis with proton-conducting solid oxide fuel cells

¹Department of Environment Systems, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8563, Japan

²Research Institute of Energy Frontier, Department of Energy and Environment, Research Institute of Energy Frontier, AIST Tuskuba West, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan

Adv. Mater. Lett., 2019, 10 (8), pp

DOI: 10.5185/amlett.2019.2259

Publication Date (Web): Jan 14, 2019

Copyright © IAAM-VBRI Press

E-mail: otomo@k.u-tokyo.ac.jp

Abstract

Direct electrochemical synthesis of ammonia was performed using proton-conducting solid oxide fuel cells. In this study, we investigated the effect of electrode potential on the reaction kinetics of ammonia formation with Fe- and Ru-based catalysts in detail. The cell configuration was Pt|BaCe_0.9Y_0.1O₃ (BCY)|K-modified Fe or Ru-BCY. The ammonia formation rate of K-Ru was higher than that of K-Fe at the rest potential. However, the ammonia formation rate significantly increased by cathodic polarization for the Fe catalyst, and it showed a linear increase for the Ru catalyst, i.e., the ammonia formation rate for K-Fe significantly increased from the rest potential by several hundred times to -1.2V at 700^oC, but K-Ru showed only a five times increase. The results suggest that the addition of K into Fe-BCY and cathodic polarization can improve the ammonia formation rate because of the promotion of bond dissociation of the N molecule on the Fe catalyst. The present work provides a hint for efficient ammonia formation and contribute to further development of ammonia electrochemical synthesis with proton-conducting solid oxide fuel cells.  © VBRI Press.

Keywords

Ammonia synthesis, proton conductor, electrochemical promotion, energy storage.