Clean synthesis of RGO/Mn3O4 nanocomposite with well-dispersed Pd nanoparticles as a high-performance catalyst for hydroquinone oxidation

In this study, a well-dispersed Pd nanoparticle (NP)-supported RGO/Mn3O4 (G/M/Pd) composite was synthesized by a clean synthetic route, where galvanic replacement reaction simply occurred between Mn3O4 and a palladium salt, thereby avoiding the use of harsh reducing and capping agents. The G/M/Pd composite served as a robust catalyst for the catalytic oxidation of hydroquinone (HQ) to benzoquinone (BQ) with H2O2 in an aqueous solution. Oxidation was completed in only 4 min, with a turnover frequency (TOF) of 3613 h(-1); this TOF is one hundred times those of previously reported Pd- and Ag-based catalysts. The superior performance was related to the electronic inductive effect between Mn3O4 and Pd NPs, which was verified by density functional theory calculations. Trapping experiments revealed that the oxidation of HQ was considerably related to the center dot OH radicals generated from the decomposition of H2O2. In addition, the influencing factors were further investigated, including catalyst and HQ concentrations, solution pH, solvents, and various inorganic and organic interferences. Moreover, the G/ M/Pd catalyst exhibits diverse applications for the catalytic oxidation of HQ derivatives with high TOFs. (C) 2019 Elsevier Inc. All rights reserved.