Doped (Nd,Ba)FeO3 oxides as potential electrodes for symmetrically designed protonic ceramic electrochemical cells

Abstract

The design of new electrode materials with high redox stability has great potential for the fabrication of solid oxide fuel and electrolysis cells having a symmetrical configuration; such a configuration is particularly promising in terms of economic and technological factors due to involving a reduced number of functional materials and technological steps. Under the framework of the present study, we developed new Nd 1-x Ba x Fe 0.9 M 0.1 O 3-δ materials (where M = Cu or Ni, x = 0.4 or 0.6), characterizing their functional properties (oxygen non-stoichiometry, thermomechanical and electrical properties) under both oxidizing and reducing conditions, as well as demonstrating the principal capability of their application as symmetrical electrodes in proton-conducting electrochemical cells. The obtained results demonstrate the desirability of a low barium content due to decreased thermal expansion coefficients and chemical strain contribution and Cu-doping due to the formation of an electrochemically active scaffold having nano-sized sediments. The Nd 0.6 Ba 0.4 Fe 0.9 Cu 0.1 O 3-δ electrodes fabricated onto the BaCe 0.5 Zr 0.3 Y 0.1 Yb 0.1 O 3-δ proton-conducting electrolytes exhibit polarization resistances of 1.1 and 15.1 Ω cm 2 at 600°C in wet air and wet hydrogen measuring atmospheres, respectively. These reported results are among the first concerning the effective operation of symmetrical electrodes in systems with proton-conducting electrolytes.

The BaCe0.16Y0.04Fe0.8O3−δ nanocomposite: a new high-performance cobalt-free triple-conducting cathode for protonic ceramic fuel cells operating at reduced temperatures

“…It was found that the ORR activity of our BCYF2 cathode in proton-conducting electrolyte surpassed most of the Fe-based cathodes reported so far. [57][58][59][60][61][62][63][64] In addition, the BCYF2 also displayed a superior ORR stability in terms of the ASR value obtained in the BZCYYbbased symmetrical cell for 180 h at 600 C in wet air (Fig. S8 †), highlighting its superiority as an efficient and durable cathode for PCFCs.…”

Electrochemistry and energy conversion features of protonic ceramic cells with mixed ionic-electronic electrolytes

“…Other examples are LaFeO 3 -, SrFeO 3 -, and BaFeO 3 -based complex oxides, which display meaningful n-type conductivity values coming from the reduction of Fe 3+ -ions: 83–85 …”

Iron-based electrode materials for solid oxide fuel cells and electrolysers

“…Pr0.4Sr0.6Co0.2Fe0.7Mo0.1O3−, (La0.6Sr0.4)0.95Fe0.8Ni0.1Mo0.1O3-δ and Pr0.6Ba0.4Fe0.8Cu0.2O3−δ have been used for the electrochemical production of ethylene from ethane in a protonic SOC at 750 o C and ammonia at low temperature, respectively [317][318][319] . Along with the development of protonic conducting SOCs operating at low temperatures [320][321][322] , the special properties of iron-based materials will find more opportunities to be used to balance the stability and performance, especially in symmetrical cells 139,323 .…”