J. Mater. Sci. Technol. ›› 2019, Vol. 35 ›› Issue (6): 1184-1191.DOI: 10.1016/j.jmst.2019.01.005

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Enhancement of oxygen evolution reaction activity and durability of Ba0.5Sr0.5Co0.8Fe0.2O3-δ by CO2 thermal treatment

Fengli Lianga*(), Ziqiong Yanga, Haipeng Denga, Jaka Sunarsob*(), Lili Yanga, Junkui Maoa   

  1. a College of Energy and Power Engineering, Jiangsu Province Key Laboratory of Aerospace Power System, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
    b Research Centre for Sustainable Technologies, Faculty of Engineering, Computing and Science, Swinburne University of Technology, Jalan Simpang Tiga, 93350 Kuching, Sarawak, Malaysia
  • Received:2018-11-14 Revised:2018-11-25 Accepted:2018-12-10 Online:2019-06-20 Published:2019-06-19
  • Contact: Liang Fengli,Sunarso Jaka
  • About author:

    1 These authors contributed equally to this work.

Abstract:

This work demonstrates that in situ formation of carbonate layer on the surface of Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF) obtained by exposure to CO2 during heating between 500 °C and 700 °C can provide enhanced oxygen evolution reaction (OER) performance and durability in an alkaline solution relative to the original BSCF. Three temperatures, i.e., 500 °C, 600 °C, and 700 °C were chosen to perform the CO2 thermal treatment, resulting into BSCF-500, BSCF-600, and BSCF-700 samples. The OER was enhanced in the order of BSCF-500 < BSCF-700 < BSCF-600. BSCF-600 showed the best OER performance, i.e., a low overpotential of 0.36 V required to attain 10 mA cm-2 current density as well as a mass activity of 74.14 $ Ag_{cat}^{-1} $ and a specific activity of 5.04 mA $ Ag_{cat}^{-2} $ at an overpotential of 0.4 V. The OER performance durability of BSCF-600 was highlighted by its ability to maintain a stable potential of around 1.61 V vs. RHE (RHE: reversible hydrogen electrode) when charged at a constant current density of 10 mA cm-2 throughout the 800 min continuous chronopotentiometry test. The enhanced OER performance for BSCF-600 relative to the original BSCF is attributed to three factors: (i) higher electrochemically active surface area; (ii) faster charge transfer rate and higher electrical conductivity; and (iii) modified oxidation state of cobalt ions. The formation of thin carbonate layer in BSCF-600 appears to suppress the durability issue observed in BSCF.

Key words: Carbonate, Electrocatalysis, Oxygen evolution reaction, Perovskite, Water splitting