One-pot synthesis of La 0.7 Sr 0.3 MnO 3 supported on flower-like CeO 2 as electrocatalyst for oxygen reduction reaction in aluminum-air batteries Yejian Xue, Heran Huang, He Miao ** , Shanshan Sun, Qin Wang, Shihua Li, Zhaoping Liu * Key Laboratory of Graphene Technologies and Applications of Zhejiang Province, Ningbo Institute of Materials Technology & Engineering (NIMTE), Chinese Academy of Sciences, Ningbo, Zhejiang 315201, PR China highlights  A novel LSM-CeO 2 hybrid catalyst has been synthesized by a facile one-pot method.  The LSM particles about 150 nm are well distributed on the flower-like CeO 2 .  The flower-like CeO 2 particles are formed from nanosheets, approx. 40 nm thick.  Hybrid material shows the remarkable catalytic activity and stability during ORR.  P max of the Al-air battery with LSM-CeO 2 hybrid material reaches 238 mW cm 2 . article info Article history: Received 2 March 2017 Received in revised form 5 May 2017 Accepted 9 May 2017 Keywords: Aluminum air battery Cerium dioxide Oxygen reduction reaction Perovskite catalyst Rotating ring-disk electrode abstract A novel La 0.7 Sr 0.3 MnO 3 -CeO 2 (LSM-CeO 2 ) hybrid catalyst for oxygen reduction reaction (ORR) has been synthesized by a facile one-pot method. The flower-like CeO 2 with the diameter of about 3 mm is formed by the agglomeration of nanosheets with the thickness of about 40 nm. The LSM particles with the diameter of about 150 nm are well distributed on the flower-like CeO 2 , thus the interaction between LSM and CeO 2 is built. Therefore, the LSM-CeO 2 composite catalyst exhibits the much higher catalytic activity toward ORR with the direct four-electron transfer mechanism in alkaline solution than LSM or CeO 2 . Furthermore, the stability of LSM-CeO 2 is superior to that of Pt/C, and the current retention is 93% after 100000 s. The maximum power density of the aluminum-air battery using LSM-CeO 2 as the ORRC can reach 238 mW cm -2 , which is about 29% higher than that with LSM (184 mW cm -2 ). It indicates that LSM- CeO 2 composite material is a promising cathodic electrocatalyst for metal-air batteries. © 2017 Elsevier B.V. All rights reserved. 1. Introduction Aluminum-air (Al-air) battery is very attractive due to its high theoretical energy density (8.1 kWh kg 1 ) and low cost [1]. The Al- air battery is mainly composed of the aluminum metal anode, alkaline aqueous electrolyte and air-breathing cathode electrode, which is generally composed of the gas diffusion layer, current collecting layer and oxygen reduction reaction catalyst (ORRC) [2,3]. The low power density seriously limits the commercial application of the Al-air batteries due to the sluggish oxygen reduction reaction (ORR) [4e6]. Therefore, ORRCs for the metal-air batteries with high catalytic activity still need to be further studied. So far, a variety of ORRCs with high catalytic activity including noble metals and their alloys, transition-metal oxides, carbon ma- terials, and organometallic macrocycles have been developed in metal-air batteries [7e13]. The Pt/C is the state-of-the-art catalyst for ORR at room temperature in the alkaline solution. However, the scarcity and high price greatly inhibit the practical application of Pt/ C. The LaMnO 3 is one of the most frequently-used ORRCs in the fuel cells and metal-air batteries [14e19], and its intrinsic ORR activity can be comparable to that of the state-of-the-art Pt/C [11]. In gen- eral, the manganese valence state of the La 1-x Sr x MnO 3 (LSM) perovskite which can be tailored by the substitution of La with Sr was proposed as an important factor for their ORR activities [15e22]. * Corresponding author. ** Corresponding author. E-mail addresses: miaohe@nimte.ac.cn (H. Miao), liuzp@nimte.ac.cn (Z. Liu). Contents lists available at ScienceDirect Journal of Power Sources journal homepage: www.elsevier.com/locate/jpowsour http://dx.doi.org/10.1016/j.jpowsour.2017.05.027 0378-7753/© 2017 Elsevier B.V. All rights reserved. Journal of Power Sources 358 (2017) 50e60