Comparison of Pyrochlore and Perovskite Electrodes Towards the Oxygen Evolution in Alkaline Media
In the present work, a comparison of OER behavior of a group of pyrochlore materials (A2B2O7-δ), and non-noble transition metal perovskites (ABO3) will be presented. The pyrochlore and perovskite structures were synthesized by a facile two-step combustion method yielding high purity phases with crystallite size in the vicinity of 20nm. The synthesized compounds include La1-xCaxFeO3, Pb2Ru2O7, and their substitutions, compared to un-supported RuO2 prepared by thermal decomposition of RuCl3. The catalysts powders were dispersed on a Nafion containing solution to form a catalyst ink . The samples were tested in alkaline media in a traditional three-electrode system under continuous N2purging. Among the characteristics that make pyrochlores attractive for oxygen electrodes, is the unusual framework containing high density of oxygen vacancies and their apparent ordering which is believed to aid in the oxygen anion mobility . Perovskite materials are attractive due to the wide range of substituting elements that can be employed to tune their electrocatalytic properties.
All the samples were characterized by XRD for phase analysis, XPS for valency, SEM for surface morphology. The OER electrochemical performance has been investigated by means of steady state current measurements. XRD spectra of selected samples and the OER activity are presented in Figure 1a and 1b, respectively. The effect of dopant concentration on the oxygen evolution activity will be discussed.
This work is supported by the IGERT-NSF fellowship and partially funded by the US Department of Energy/NETL, Oak Ridge Institute for Science and Education (ORISE) fellowship.
 Malkhandi, S., Yang, B., Manohar, A.K., Manivannan, A., Surya Prakash, G.K., and Narayan, S.R., J. Phys. Chem. Lett. 2012, 3, 967-972.