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

Abstract In this study, a well-dispersed Pd nanoparticle (NP)-supported RGO/Mn 3 O 4 (G/M/Pd) composite was synthesized by a clean synthetic route, where galvanic replacement reaction simply occurred between Mn 3 O 4 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 H 2 O 2 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 Mn 3 O 4 and Pd NPs, which was verified by density functional theory calculations. Trapping experiments revealed that the oxidation of HQ was considerably related to the ·OH radicals generated from the decomposition of H 2 O 2 . 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.