PtRu/C-LaNiO₃Composite Electrodes for Electrocatalysis

Abstract

PtRu/C-LaNiO 3 composite coatings on Ni foam supports were prepared by brush painting and characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy analysis and cyclic voltammetry. The electrodes electrocatalytic properties toward the oxygen evolution reaction in alkaline medium were evaluated by steady state measurements. The results show that PtRu/C loading of 5% produce electrodes more active than the LaNiO 3 coating for the oxygen evolution reaction. The improved electrocatalytic performance of the composite electrodes was related to the increase of the exchange current density and the shift of the Tafel lines for less positive potentials compared to the LaNiO 3 oxide electrodes. The enhanced performance of the composite electrodes was attributable to enhancement of the electrical conductivity, higher surface area and to the electrocatalytic nature of the composite.Oxygen evolution reaction (OER) is one of the processes currently limiting the performance of Regenerative Fuel Cells (RFCs). The reaction exhibits severe electrochemical overpotential which lowers the energy efficiency of RFCs. Noble metals are still considered the best electrocatalysts for the oxygen reactions as they provide the lowest overpotential and highest stability. However the level of precious metal required for high activity and stability leads to high costs. Alternative materials such as mixed oxides are very interesting for catalytic applications and its combination with small amounts of precious metals could lead to improved electrode activity for OER due to synergistic effect between noble metal and oxide. 1-4 The perovskite oxide LaNiO 3 is among those considered for use as electrocatalyst and electrocatalyst support in RFC systems due to its metallic conductivity, reasonable stability and low cost. Recently it was proposed by Yuasa et al. the use of LaNiO 3 as a potential material to replace carbon black, owing to its higher stability against anodic polarization as compared to carbon support. 5 During the past years our efforts have been devoted to study coated electrodes, based on the perovskite-type oxide LaNiO 3 , in order to optimize their performance for the OER, via the use of an adequate oxide preparation method and the choice of Ni foam as support. [6][7][8][9] In order to improve the performance of these coated electrodes, the addition of PtRu nanoparticles supported on Carbon was attempted. In this work we present our results on the performance of PtRu/CLaNiO 3 composite coatings on Ni foam supports as anodes for OER in alkaline medium. The electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy analysis (EDS) and cyclic voltammetry (CV). Their electrocatalytic properties were evaluated by steady state measurements.The comparison with LaNiO 3 oxide coatings on Ni foam supports shows the manifested benefit of the addition of PtRu/C nanoparticles on the improvement of the composite electrode activity for the OER. ExperimentalThe perovskite-type oxi...

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