Silicon carbide-silicon as a support material for oxygen evolution reaction in PEM steam electrolysers

Aleksey Nikiforov, Irina Petrushina, Erik Christensen, Antonio Luis Tomás García, Niels Bjerrum

Research output: Contribution to conferencePosterResearch

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Abstract

There is a demand to develop a corrosion resistant and conductive substrate for the anode electrocatalyst, which can assist in the reducing of noble catalyst loading without a significant loss of performance. It was shown that SiC can act as a support material for platinum electrocatalyst in fuel cells. In the present work a commercial SiC-Si, produced by the Acheson process, with a fraction of free silicon around 20% wt. was investigated as a catalyst support for anode electrocatalyst in PEM steam electrolysers. This electrocatalyst system was characterized using several techniques such as XRD, cyclic voltammetry, SEM, EDX and steady state electrochemical polarisation in a working PEM steam electrolyser. Several SiC-Si-IrO2 electrodes have been prepared and tested. The iridium oxide content at the electrode active layer varied from x=0.2 to x=1, corresponding to the general formula (1-x)(SiC-Si)-x(IrO2). Compositions in this range were tested with the step difference in x=0.1. A diameter of about 5-6 nm of individual IrO2 crystallites was measured by X-ray diffraction and calculated from the Scherrer equation. The particle size distribution of SiC-Si was measured by the X-Ray sedimentation technique and the average particle diameter of silicon carbide-silicon was found to be in the range of 5-10 µm, while its specific surface area was about 5 sq.m/g. The oxygen evolution reaction was studied by the cyclic voltammetry technique in 85% phosphoric acid solution at temperatures between 22 and 150 degrees C in a conventional three-electrode cell. Fig. 1 shows cyclic voltammograms, recorded with the prepared supported and unsupported iridium oxide on tantalum electrodes. There was an evident increase in associated voltammetric capacitance value corresponding to the supported catalyst compared to the pure oxide catalyst material. This indicates a relatively higher number of active sites deduced from the charge transferred when cycling the potential between two preselected values. Based on the above results, the SiC-Si compound is a potential candidate as a support for the anode electrocatalyst for phosphoric acid doped membrane steam electrolysers.
Original languageEnglish
Publication date2010
Number of pages1
Publication statusPublished - 2010
EventProgressMEA 2010: Progress in MEA Materials for Medium and High Temperature Polymer Electrolyte Fuel Cells - La Grande Motte, France
Duration: 19 Sep 201022 Sep 2010
Conference number: 2

Conference

ConferenceProgressMEA 2010: Progress in MEA Materials for Medium and High Temperature Polymer Electrolyte Fuel Cells
Number2
CountryFrance
CityLa Grande Motte
Period19/09/201022/09/2010

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