Preparation and Characterization of Polyaniline/ZnO Composite Sensor

Abstract

Polyaniline/ZnO nanocomposite thin films were prepared via an electrochemical synthesis route on ITO coated glass substrates. ZnO nanoparticles were uniformly dispersed in to the polyaniline matrix. Interaction between ZnO nanoparticle and polyaniline has been studied using X-ray diffraction (XRD), UV-Vis absorption spectroscopy, PL spectroscopy, AFM and I-V characteristics. The ammonia gas sensing behaviors of the polyaniline/ZnO composites were examined at room temperature. It was observed that the composite films showed good sensitivity, improved doping state and enhanced photoluminescence behaviour.Keywords: Polyaniline; ITO; AFM; UV-Vis absorption spectroscopy; Nanocomposites Ammonia plays very crucial role for human health. The way of natural process in animals, human and plants are responsible for production of ammonia in atmosphere. High concentrations of ammonia can cause difficulty in breathing, irritation to the eyes and skin and long term exposure of NH 3 leads to fatal [1]. There is a variety of applications of artificially synthesized ammonia in chemical industry, fertilizer factories, textile, food processing, bleaching products and refrigeration systems [2]. Therefore the human activity is a main reason for the presence of larger amount of ammonia in our atmosphere and is a necessity to detect its presence. Hence much research has been focused on the development of suitable gas sensitive materials to detect lower concentration of NH 3 with excellent performance [3].There are several studies concerning metal oxides like SnO 2 , WO 3 , ZnO, TiO 2 for NH 3 sensing applications but generally it requires a high working temperature [4,5]. There are also several conducting polymers like polythiophene, polypyrrole and polyaniline are used for detecting gases, however, the poor selectivity is the main disadvantages of pure inorganic and organic materials. New and interesting properties can be achieved by combining organic and inorganic materials [6]. Therefore conducting polymer/inorganic nanocomposites are explored as promising materials for sensing application, because of their good ability and compatibility to form chemical sensors with higher sensitivity at room temperature.Among the conducting polymers polyaniline based nanocomposites have many advantages. In literature, there are some reports available concerning the synthesis of polyaniline/ metal oxide nanocomposites in gas sensing applications. Huyen et al. [7] synthesize polyaniline/TiO 2 nanocomposites and studies the effect of TiO 2 on the sensing features. Lee et al. [8] described the effects of O 2 plasma treatment on NH3 sensing characteristics of multiwall carbon nanotube/polyaniline composite films. Wu et al. [9] reported the characterization and gas sensitivity study of polyaniline/SnO 2 hybrid material prepared by hydrothermal route. Deshpande et al. [10] reported tin oxide-intercalated polyaniline nanocomposite for ammonia gas sensing applications.We employed simple electrochemical technique to synthesize polyaniline/ZnO nanoco...

Facile Fabrication of an Ammonia-Gas Sensor Using Electrochemically Synthesised Polyaniline on Commercial Screen-Printed Three-Electrode Systems

“…In the case of a three-electrode SPE, only a drop of electrolyte is needed, and when a conductive material is electrochemically deposited on the working electrode, for further functionalisation, only suitable contacts on the top of the deposited material still need to be made. These contacts must not be in contact with the working electrode, but must connect the deposited material with the secondary electrode [48]. The deposited material and the type of synthesis represent a bottleneck for these approaches.…”

ZnO/polyaniline composite based photoluminescence sensor for the determination of acetic acid vapor

“…The common idea is that the increase in the response magnitude of the composites should be due, more than to the increased specific surface area of nanostructures, to the formation of p/n junction between p-type HCl doped polyaniline thin film and n-type ZnO semiconductor. The appearance of a variety of p-n semiconductor contacts likely facilitates the formation of various molecular adsorption sites on the polyaniline surface thus the sensitivity is increased as compared to pure ZnO or polyaniline [24,26,28]. We suppose that acetic acid detection occurs due to interaction between NH2-groups and the target molecules.…”

Instrumented indentation of PMMA/ZnO nanocomposites films

“…The diffraction pattern of nanocomposite thin films revealed a highly crystalline wurtzite structure of ZnO. The characteristic peaks of ZnO are shifted to the right approximately 0.5 degrees from their standard position in PMMA/ZnO nanocomposites due to the strong interaction between PMMA polymer and ZnO nanoparticles[28]. Moreover, it confirms the formation of the composite and suggests that there are no structural alterations, only a conformational change in the polymer backbone as a result of adding ZnO nanoparticles[29].Figures 4(a) to (d) illustrates the top surface SEM micrograph of nanocomposite film.…”