Investigation of fumed silica as a platinum support for methanol oxidation reaction

Abstract

In this study, we have examined fumed silica (FS) as a support material for platinum (Pt) catalyst used in methanol fuel cells for the first time. For this purpose, the carbon paste electrode (CPE) was modified with different amounts of FS to prepare CPE/xFS (x: 3, 6, 9, 12%), and then these electrodes were electrochemically coated with Pt nanoparticles to obtain CPE/xFS@Pt. The presence of FS as a support material prominently increased the methanol oxidation activity of the prepared electrodes. The highest activity was obtained in the presence of 12% FS. Characterizations were performed with cyclic voltammetry (CV), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and contact angle measurements. SEM and EDX analyses revealed that FS and electroplated-Pt homogeneously distributed on the electrode surface. SEM analyses also showed that the synthesized Pt nanoparticles formed a brain-like structure having inter-connected helical particles. The presence of FS increased the electron transfer rate, the effective surface area, and the hydrophilicity of the electrode surface. The CPE/12FS@Pt preserved its methanol oxidation activity for long periods. The results showed that FS was a highly efficient and durable supporting material for Pt-based catalysts which were used in direct methanol fuel cells.