In Situ H2O2 Generation for Tuning Reactivity of V4O7 Nanoflakes and V2O5 Nanorods for Oxidase Enzyme Mimic Activity and Removal of Organic Pollutants

Abstract Surface oxidation state mediated oxygen vacancies of metal oxide enhance oxidase-enzyme mimic, catalytic, and photocatalytic activity of the catalyst. Herein, we prepared the mixed valence V4O7 (V+3/V+4), which was thermally (650 °C) oxidized to produce V2O5 (V+5) nanorods. For the first time, we demonstrate that vanadium oxides (V4O7 and V2O5) exhibit catechol oxidase-like activity using the in situ production of H2O2. In addition, both metal oxides exhibit photocatalytic activity for organic pollutants removal in absence and enhanced in presence of H2O2. Catalytic and photocatalytic activities were modulated by the change in surface oxidation sate and oxygen vacancies tuned through the facile charge immobilization on V4O7 (V+3/V+4) to the less active V2O5 (V+5). The V4O7 shows enzyme activity higher than the corresponding V2O5 nanorods. On the other hand, the mixed valance V4O7 (V+3/V+4) was superior photocatalyst for remediation of methylene blue as it completely removes the dye in less than 15 min in presence of visible light.