Electrochemical Characterisation of Cobalt-Oxide Catalysts with Different Cobalt Loading for Oxygen Reduction Reaction in Alkaline Media

Alkaline fuel cells are very promising because of their high efficiencies (1). In fuel cells the reduction of oxygen on cathode side is the performance-limiting step (2, 3). Catalysts, e.g. platinum, are used to enhance the oxygen reduction reaction (ORR) rate and also the performance. Due to the high costs of the fuel cell components, especially for the platinum catalyst (4), the fuel cell is not common for various applications up to now. The alkaline media enables the use of non-precious metals, e.g. cobalt or manganese oxides (5-8), to enhance the kinetic on the cathode side.

The electroactivities of different non-precious metal catalysts like cobalt oxide are promising to achieve a similarly high activity as platinum. A cobalt acetate precursor is plasma-treated and resulting cobalt oxide catalysts with different cobalt loading were investigated in different alkaline media and at temperatures between 25 and 75 °C using a rotating ring disk electrode (RRDE) analysis. The advantage of plasma treatment is the better distribution of particles, they are less agglomerated compared due to the common heat treatment (9-11). This leads to a higher activity of the catalyst material (9). Different characterisation methods are used to identify the catalyst material like XRD, TEM and SEM. A custom-built Teflon cell is used for the RRDE analysis to avoid glass corrosion in alkaline media. Glass corrosion affects the electrochemical measurements (12), therefore it is necessary to replace glass components for the experiments.

References:

1.            E. Gülzow, Fuel Cells, 4, 251 (2004).

2.            K. Kordesch, V. Hacker, J. Gsellmann, M. Cifrain, G. Faleschini, P. Enzinger, M. Ortner, M. Muhr and R. R. Aronson, Jounal of Power Sources, 5 (1999).

3.            B. Viswanathan, C. V. Rao and U. V. Varadaraju, in Photo/Electrochemistry & Photobiology in the Environment, Energy and Fuel, p. 43 (2006).

4.            G. Wu, K. L. More, C. M. Johnston and P. Zelenay, Science, 332, 443 (2011).

5.            S. Lu, J. Pan, A. Huang, L. Zhuang and J. Lu, Proc. Natl. Acad. Sci. U. S. A., 105, 20611 (2008).

6.            H. Meng and P. K. Shen, Electrochem. Commun., 8, 588 (2006).

7.            F. Cheng, J. Shen, W. Ji, Z. tao and J. Chen, Applied Materials & Interfaces, 1, 460 (2009).

8.            M. Mamlouk, S. M. S. Kumar, P. Gouerec and K. Scott, J. Power Sources, 196, 7594 (2011).

9.            V. Brüser, N. Savastenko, A. Schmuhl, H. Junge, I. Herrmann, P. Bogdanoff and K. Schröder, Plasma. Process. Polym., 4, S94 (2007).

10.          N. A. Savastenko, K. Anklam, A. Quade, M. Brüser, A. Schmuhl and V. Brüser, Energy Environ. Sci., 4, 3461 (2011).

11.          I. Herrmann, U. I. Kramm, S. Fiechter, V. Brüser, H. Kersten and P. Bogdanoff, Plasma. Process. Polym., 7, 515 (2010).

12.          K. J. J. Mayrhofer, G. K. H. Wiberg and M. Arenz, J. Electrochem. Soc., 155, P1 (2007).