Improvement in stability of carbon support for platinum catalyst by applying silicon carbide coating

Abstract

Silicon-carbide-coated carbon blacks (SiC/C) were investigated as support materials of platinum (Pt) nanoparticles to improve their stability. The support materials were synthesized by pyrolyzing the mixture of polycarbosilane and carbon blacks. An elemental mapping image of the support material showed that the carbon black was coated with a layer of silicon carbide less than 10 nm thick. Both the electric resistance and surface area of the support materials were of the same order as the carbon black only. The platinum nanoparticles were deposited on the support materials by electroless plating. The oxygen reduction activity of the catalysts was measured electrochemically using a rotating disk electrode. The measurement showed that the specific activity of the catalyst increased when silicon carbide was added. The catalyst stability was evaluated using thermogravimetric (TG) analysis in air from room temperature to 1273 K and potential-cycling test between 1.0 and 1.5 V. These results revealed that the catalyst stability of Pt/SiC/C was higher than that of Pt/C. This high stability of Pt/SiC/C is attributed to the protective effect of SiC against carbon corrosion that is enhanced by the platinum nanoparticles.