Preparation of anode catalysts for sorbitol electrooxidation based on the nanocomposites of fumed silica, reduced graphene oxide and gold nanoparticles

Abstract

In this study, fumed silica (FS), reduced graphene oxide (rGO), and their hybrid (FS-rGO) are tested as support materials for Au nanoparticles to prepare anode catalysts for sorbitol fuel cells. Chemical reduction method is used to obtain Au@FS, Au@rGO, and Au@FS-rGO catalysts characterized by SEM, EDAX, TEM, XRD, and Raman analysis. The Au contents of the catalysts are determined as 32.5% (Au@FS), 32% (Au@rGO), and 32.8% (Au@FS-rGO). Diameters of Au nanoparticles are measured as 1.51 nm (Au@FS), 5.90 nm (Au@rGO), and 7.05 nm (Au@FS-rGO). The highest current density for sorbitol oxidation is obtained with Au@FS-rGO. The onset potential of sorbitol oxidation obtained with Au@FS-rGO (0.007 V) is much smaller than those of Au@FS (0.028 V) and Au@rGO (0.038 V), indicating the synergistic effect of FS and rGO. FS significantly increases the activity and stability of the catalysts compared to rGO one of the commonly researched support materials in fuel cells.