Superior dye degradation using SnO2-ZnO hybrid heterostructure catalysts

Abstract

We investigated the efficiency of oxide based hierarchical heterostructure as adsorbent for the treatment of organic dyes, Methyl orange (MO) and Methylene Blue (MB), containing solution. Nanocrystals such as ZnO nanorods (at various temperatures of 30, 60 and 75 °C) and SnO2 nanoparticles were synthesized by electrodeposition method and hydrothermal approaches, respectively. SnO2-ZnO heterostructures were formed by spin coating SnO2 nanoparticles on ZnO nanorods matrix to form a heterostructured film. The surface morphologies and structural characterization of as-prepared heterostructures were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) techniques. While, absorption spectra of all samples were examined by UV-vis diffuse reflectance spectroscopy. The photocatalytic activities of as-prepared samples for organic dyes degradation were tested under UV light as model reaction. The SnO2-ZnO heterostructured photocatalyst showed superior activities than individual ZnO and SnO2 nanocrystals. This heightened behavior was attributed to its better charge separation capability and the slow charge recombination originating due to difference in energy values of conduction band edges of SnO2 and ZnO. The SnO2-ZnO heterostructure demonstrated better stability and recyclability up to five times, which is highly desirable for potential industrial applications including dye degradation and wastewater treatment systems.