Indomethacin–V 2 O 3 –Reduced Graphene Oxide Nanocomposites as Catalysts in the Electro-Fenton Process

A single-step sonochemical method (20 kHz) is demonstrated for the functionalization of reduced graphene oxide (rGO) with V2O3 and indomethacin complexes to form catalytically efficient an indomethacin–V2O3–rGO nanocomposite with rodlike shape and average diameter (44.6 ± 8.3) nm without any surface active additives in an aqueous medium. UV–vis absorption, infrared, and Raman spectroscopies confirm that the formation of an indomethacin–V2O3–rGO nanocomposite relies on sonochemical complexation of indomethacin with vanadium trioxide and rGO through covalent binding with V–O–V, C–C ring, and −C(═O)–OH groups involving H-bond formation. Sonochemically designed indomethacin–V2O3–rGO nanocomposites can accelerate the single-electron transfer reaction in the redox couple Fe(CN)63–/S2O32– by ∼25.6 times higher than that in pristine indomethacin. The enhanced catalytic activity of nanocomposites is due to covalently bonded V2O3, rGO, and indomethacin, including complexes of indomethacin with vanadium and VO(IV), conjugated indomethacin–rGO structure, and H-bond formation. Indomethacin–V2O3–rGO nanocomposites are efficient hydroxyl radical scavengers in the electro-Fenton process due to indomethacin–vanadium complexes, with the activity being by ∼13.6 times higher than that of pristine indomethacin and not accessible by V2O3–rGO.