Development of nanostructures by electrochemical method for chemical sensors

Abstract

Innovations based on nanotechnology are introduced in the field of chemical sensors to reduce the sensor dimensions and increase the surface-to-volume ratio and for low power operation of a reliable sensor with faster response and quicker recovery. The formation of nanoporosity with controlled dimensions is another important parameter of the superior nanomaterials and thin films for chemical sensors. The response time can be reduced to as low as millisecond by the choice of appropriate nanostructures, and the selectivity can be improved to a large extent. Thus the material properties can be tailored to enhance the sensor performance. The electrochemical anodization is one of the modern techniques to meet the above challenges. This simple yet versatile method introduces a significant difference for achieving superb nanostructure morphology by manipulating the simple parameters like electrolyte composition, concentration, conductivity, and anodization voltage. It is realized by now that the electrochemical method can control the architecture from well-separated nanostructures to densely packed arrays where the aspect ratio can be monitored by selecting the appropriate electrolyte, the anodization voltage, and UV radiation. Moreover, the electrochemical anodization can be performed at room temperature that can avoid the grain growth and degradation of the grown materials, normally experienced in high-temperature growth technique. This chapter also highlights the appropriate characterization methods for nanocrystalline and nanoporous materials and thin films. The state-of-the art chemical sensors using electrochemically grown nanostructures of ZnO, TiO2, SnO2, and porous silicon are analytically discussed. The updated relevant literature References are included in the chapter.