CERAMICS INTERNATIONAL Available online at www.sciencedirect.com Ceramics International 40 (2014) 13753–13756 Short communication Fabrication and evaluation of Sm 0.5 Sr 0.5 CoO 3  δ impregnated PrBaCo 2 O 5 þ δ composite cathode for proton conducting SOFCs Xinguo Xi a , Xiahui Chen b , Guihua Hou a , Ning Xu a , Qinfang Zhang a , Zetian Tao a,n a Key Laboratory for Advanced Technology in Environmental Protection of Jiangsu Province, Yancheng Institute of Technology, Yancheng 224051, China b School of Microelectronics and Solid-State Electronics, University of Electronic Science and Technology of China, Chengdu 610054, China Received 23 April 2014; received in revised form 14 May 2014; accepted 18 May 2014 Available online 27 May 2014 Abstract High catalytic activity PrBaCo 2 O 5 þ δ (PBC) cathode with impregnated Sm 0.5 Sr 0.5 CoO 3 δ (SSC) was investigated as a highly active cathode for intermediate-temperature SOFCs (IT-SOFCs) with BaZr 0.1 Ce 0.7 Y 0.2 O 3 δ (BZCY7) electrolytes. The nanoscale impregnated SSC particles were deposited on the surface of the PBC framework. The single cell with impregnated SSC cathode was tested from 600 to 700 1C with humidified hydrogen (  3% H 2 O) as the fuel and the static air as the oxidant, and showed higher performance than the cell with pure PBC cathode. The results indicated that the impregnation method can be promising ways to improve the catalytic activity of cathode for proton- conducting SOFCs. & 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Keywords: Impregnation; Composite cathode; Solid oxide fuel cells; Impedance spectroscopy; Catalysis activity 1. Introduction Solid oxide fuel cells (SOFCs) have attracted much attention worldwide because of the demand for clean, secure, and renewable energy [1,2]. Unfortunately, the expensive SOFC system limits the commercial use for the high operating temperature. The reduction of the working temperature of SOFCs becomes the urgent demand for broad commercializa- tion [3]. Intermediate-temperature SOFCs, especially proton- conducting SOFCs attract considerable interest for those low operating temperatures [4–7]. Proton-conducting SOFCs have some advantages compared with oxygen conducting SOFCs, such as low activation energy and high energy efficiency. However, the development of proper cathode materials for proton-conducting SOFCs remains a challenge because the cathode materials sensitively affect the performance of intermediate-temperature SOFCs. Many traditional cathode materials researched for oxygen ion conducting SOFCs such as La 1 x Sr x MnO 3 do not have enough catalytic activity to induce the oxygen reduction reaction at the intermediate temperature range because of their low oxygen permeability which thereby limits the oxygen reduction rates in the triple phase boundary (TPB) [8,9]. Recently, Zhang et al. [10] have reported that PrBaCo 2 O 5 þ δ had the highest bulk diffusion coefficient and surface exchange coefficient among the various layered LnBaCo 2 O 5 þ δ oxides, and Zhao et al. [11] find that PrBaCo 2 O 5 þ δ could be the potential cathode for proton- conducting IT-SOFCs. Meanwhile, Sm 0.5 Sr 0.5 CoO 3 δ has been proved to be a potential cathode with high catalysis ability for SOFCs [12]. In addition, another feasible way to improve the cell performance is to increase the tripe-phase boundary of cathode which is positive correlation to the cell performance [13]. One important way is adopting the technique of impregnation to obtain nanostructure cathode [14,15]. The specific surface area is obviously increased and the cell performance would be significantly improved. In the present study, we employed impregnation technology to fabricate Sm 0.5 Sr 0.5 CoO 3 δ impregnated PrBaCo 2 O 5 þ δ composite cathode which have nanostructure and high surface area to obtain high catalysis ability. With the cathode for www.elsevier.com/locate/ceramint http://dx.doi.org/10.1016/j.ceramint.2014.05.082 0272-8842/& 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved. n Corresponding author. Tel.: þ86 515 88298923; fax: þ 86 515 88298927. E-mail address: newton@mail.ustc.edu.cn (Z. Tao).