Technical Communication Electrochemical study of La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 during oxygen evolution reaction Eric M. Garcia a, *, Hosane A. Taro ˆco b , Tulio Matencio a , Rosana Z. Domingues a , Jacqueline A.F. dos Santos a a Universidade Federal de Minas Gerais e UFMG, Av. Anto ˆnio Carlos, 6627, Pampulha, Belo Horizonte, MG, CEP 13565-905, Brazil b Federal University of Sa ˜o Joa ˜o Del Rei e UFSJ/Sete Lagoas, Rodovia MG 424, Km 47, Sete Lagoas, MG, CEP 35701-970, Brazil article info Article history: Received 29 November 2011 Received in revised form 6 January 2012 Accepted 13 January 2012 Available online 17 February 2012 Keywords: Oxygen evolution reaction LSCF Oxidative processes abstract In this paper, oxygen evolution reaction (OER) mechanism in La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 was investigated in KOH solution by electrochemical impedance spectroscopy (EIS) and vol- tammetric measurements. The Tafel slopes and reaction orders evaluated in this paper are consistent with the B. O’Grady’s Path for oxygen evolution on oxides. The activation energy for OER in La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 was 28.3 kJ mol 1 . The obtained apparent porosity of La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 electrode is 48% and the roughness factor is around 1.6  10 4 . The polarization resistance of La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 is much low compared with other similar oxides. This can be due the high roughness and high porosity in addition to the low active energy for the process. Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. 1. Introduction The hydrogen can be considered one of the most promising energy carriers because it is ideal for applications in fuel cells, which are clean and renewable [1e3]. The water electrolysis is the most attractive route among the existed processes for very pure hydrogen generation [1,3]. The hydrogen evolution reaction (HER) is not applied only in water electrolysis, but also in several electrochemical devices as regenerative fuel cells, secondary batteries, electrochemical pseudo capacitors and many others systems. Many papers describe the elec- trolysis of water in alkaline medium. This medium is preferred because the oxygen evolution reaction (OER) (Equation (1)) occurs at lower overpotential [1e3]. Moreover the range of suitable electrode materials for alkaline medium is larger and they are cheaper than electrode materials for neutral or acid medium [3,4]. 2OH  ðaqÞ /H 2 O þ 1 2 O 2ðgÞ þ 2e  (1) The mechanism for OER generally involves the OH  adsorption as first step [4,5]. Thus, a transition metal ion with multiple valence and strong bonding power is necessary [5,6]. Considering this fact, a lot of catalysts were tested as anode materials for a more efficient and economic water electrolysis. In recent years, many efforts have been done to development of new anodes for oxygen evolution in alkaline media [3,4,9]. This has been focused [7,8] on the base metals (e.g., Fe, Mn, Ni, and Co) or base metal oxides (e.g., Fe 3 O 4 , MnO 2 , NiO, and Co 3 O 4 ) to decrease the cost. These materials (oxide and * Corresponding author. Tel.: þ55 31 3409 5714; fax: þ55 31 3409 5700. E-mail address: ericmgmg@hotmail.com (E.M. Garcia). Available online at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 37 (2012) 6400 e6406 0360-3199/$ e see front matter Copyright ª 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2012.01.058