Reduced Graphene Oxide Supported Silicotungstic Acid for Efficient Conversion of Thiols to Disulfides by Hydrogen Peroxide

Reduced graphene oxide (RGO) supported silicotungstic acid (STA) as a redox catalyst (STA-RGO) for efficient conversion of thiols to disulfide was prepared with an impregnation method. The catalyst was characterized by XRD, FTIR, UV-vis, TEM techniques, and zeta potential measurements. The uniform distribution of the STA on RGO was indicated by broadening of the XRD peaks of RGO. The Keggin unit of STA on the prepared catalyst was found to remain intact as noticed by FTIR. The increase in negative zeta potential and shifts in the characteristic UV-vis absorption bands of STA-RGO as compared with pure STA and RGO indicate the interaction between the two. The prepared catalyst was found to facilitate the oxidation of various thiols to their corresponding disulfides in the presence of hydrogen peroxide as an oxidant at room temperature. A probable mechanism involving sufenic acid as an intermediate is proposed.