Facile fabrication of magnesium peroxide with different morphologies via the isomorphic transformation of magnesium oxide for Fenton-like degradation of methylene blue

Magnesium peroxide (MgO2) has been widely used in the field of environmental remediation including organics degradation and bacterial inactivation, due to its good stability, environmental friendliness and high active oxygen content. In this work, MgO2 rod, cube and flower were synthesized firstly by the reaction of isomorphic MgO and H2O2, and used as Fenton-like oxidants for methylene blue (MB) degradation. The structure and morphology of as-prepared products were characterized by XRD, SEM and TEM techniques. It was found that the synthesized MgO2 retained the original morphologies of MgO precursors. The MgO precursors firstly interacted with H2O to produce hydrated MgO intermediate (MgOH+), which was further oxidized into MgO2 by H2O2. The flower-like MgO could be completely converted into MgO2 phase in a relatively short time, due to the porous structure assembled by thin nanosheets. Besides, the MgO precursors also served as self-templates for in-situ growth of MgO2, allowing the MgO2 products to maintain the morphological characteristics of MgO precursors. The results of degradation experiments showed that MgO2 rod exhibited better performance for MB degradation than MgO2 cube and flower, owing to its unique structure and high active oxygen content.