Adsorption Dependent Fenton-like Catalysis on Graphene Oxide-Fe3O4 Composite: Electron Transfer Mediated by Target-catalyst Interactions

Recently, the non-radical oxidation routes involved in the Fenton-like systems have received much concern as it is thought to be a highly efficient catalytic process compared to the free radical oxidization which suffers from the quenching effects of the radicals. In this study, an unprecedented non-radical pathway is found in the degradation of phenol with H2O2 used as the oxidant and graphene oxide-Fe3O4 composite ([email protected]3O4) as the catalyst. The kinetics investigation shows the degradation rate at 318 K is higher than the value calculated according to the arrhenius equation fitting, implying different catalytic process included. In addition, the non-radical route is verified by ESR spectra in which the species of singlet oxygen (1O2) rather than the radical of •OH is revealed to be preferentially generated during the activation of H2O2 by [email protected]3O4. Distinct structural variation could be observed from the XPS and IR spectra of [email protected]3O4 before and after the phenol adsorption, which indicates the covalent interactions of phenolic hydroxyl to Fe atoms and H-bond to the alcoholic hydroxyl groups of GO. The oxidation of phenol appears to undergo a target adsorption mediated electron transfer pathway, resulting in the apparent increasement of degradation efficiency. The mechanism proposed in this work will shed light on the interpretation of adsorption dependent catalytic Fenton-like degradation.