An Anodization, Precursor Route To Flower-like Patterns Composed Of Nanoporous Tin Oxide Nanostrips On Tin Substrate

Tin oxide (SnO₂) is an important n-type semiconductor possessing unique electronic, optical and photoelectrical properties. SnO₂ has wide applications in many aspects such as gas sensors, lithium batteries, solar cells, and catalysts. It will be a useful tool for the tailoring of properties/applications of tin oxide material if we can precisely control the sizes, dimensionalities, shape, structure and compositions in nanoscale. Many investigations have shown that compared to bulk materials, one-dimensional (1D) nanomaterials, such as nanowires, nanobelts, and nanotubes exhibit enhanced or novel physical properties due to the restricted size and higher surface area. As a result, the research of the one-dimensional nanomaterials become popular more and more. In this thesis, salutary explorations have been developed on the synthetic strategy and formation mechanism of tin oxide nanomaterial.The anodization technique is a commonly used surface treatment method for decorating a metal surface and/or increasing corrosion/wear resistance. Since the breakthrough in the anodic formation of self-ordered porous oxide films on aluminum, the anodization techniques has attracted considerable attentions as it enables the formation of nanostructured metal oxides with unique physical and chemical properties. For example, a range of valve metals, such as Ti, Zn, W, Ta, Hf, Zr, Nb and highly ordered nanoporous or nanotube oxide structures have been successfully formed by anodization. However, reports on the formation of nanostructured SnO₂ by anodization are few. Our research based on the technology of anodic oxidization, We also report that polycrystalline SnO₂ nanostrips with a porous structure .In present work, we report for the first time an investigation on anodic oxidation of tin in an electrolyte of dimethyl sulfoxide (DMSO)/water mixtures containing citric acid in the trans-passive region. The anodization leads to the formation of flower-like patterns composed of tin citrate complex nanostrips on tin substrates. The products were characterized using XRD, SEM, TEM, FTIR, and XPS measurements. The formation mechanism of the tin citrate complex microstructures is discussed and the influences of the voltage, citric acid concentration, and electrolyte composition on the morphology of the microstructures were investigated. The nanostrips with a smooth surface can be transformed to polycrystalline SnO₂ nanostrips with a porous structure by a thermal annealing process. This work developed a simple, clean, and effective route for fabrication of large area SnO₂ nanostructured films.