Integrating biphase γ- and α-Fe2O3 with carbon dots as a synergistic nanozyme with easy recycle and high catalytic activity

Abstract A new method is offered for the synthesis of heteronanostructures as a multifunctional catalyst mimicking functions of dual- or multi-enzyme activities. In this method, the coordination reaction and surface adsorption are firstly used to preform ferrous and ferric ion-modified carbon dots (CDs) for regulating heterogeneous nucleation process of iron oxide. Thus a unique multiphase nanostructure containing CDs and biphase γ- and α-Fe2O3 is obtained under hydrothermal conditions. As-prepared heteronanostructure with magnetic properties shows excellent enzyme-like activities under visible light irradiation, which is more than a 6-fold enhancement compared to pure phase Fe2O3 nanomaterials. This could be attributed to highly efficient charge separation and transfer efficiency induced by heterogeneous interfaces as well as multiphase-induced new electronic energy level structure. Moreover, its catalytic activities can be also tuned by temperature, pH, hydrogen peroxide and levels of oxygenation in microenvironments. Not only does this work open an effective strategy to design novel heteronanostructures, but it also may provide a synergistic nanozyme as a multimodal platform for a broad of applications.