Surfactant-Free Hydrothermal Synthesis of SnO2 Powders with Controllable Morphologies and Their Photocatalytic Water Treatment Application

The controlled growth of nanomaterials with specific geometrical microstructures is an effective strategy for improving the optical and electrical properties of these materials. In this paper, pure rutile-phase SnO2 nanoparticles with different three-dimensional microstructures (e.g., flower-like architectures and microspheres) were prepared via a feasible surfactant-free hydrothermal process. These microstructures were composed of nanosheets, nanocubes and nanopyramids. By changing the amount of ethanol additive, the growth orientation and size of the SnO2 nanocrystals were varied, which resulted in the formation of different growth patterns. The effects of ethanol content on the morphological evolution of the SnO2 nanoparticles and the formation mechanism of the flower-like architectures and nnicrospheres were explored. Furthermore, the morphologies of the SnO2 microstructures had great effects on the surface areas of the samples. The adsorption and photocatalytic properties were both found to be mainly dependent on the surface area and slightly influenced by the band gap energy. The SnO2 microspheres exhibited higher adsorption capacity and photocatalytic activity toward the degradation of acid fuchsine compared to the flower-like architectures. When the ratio of ethanol/water in the solvent was 3:1, the products were broken SnO2 nnicrospheres with both a surface area of 58.2 m(2)/g and a photocatalytic activity of 0.073 min(-1). They showed a removal efficiency of over 80% in 35 min. With excellent recycling performance, these microspheres can be used as an efficient water treatment material.