Development of a ZnO-modified Light-Scattering Sensor for the Detection of alcohols

Abstract

A light-scattering sensor that incorporated zinc oxide (ZnO) nanoparticles was developed and characterized in this study. Evenly distributed nanostructured ZnO materials were formed on the sensing elements through the calcination of zinc acetate-treated sensing elements in a high-temperature oven. There was a large change in the scattering properties of the nanostructured ZnO materials after adsorption of the target compounds; this behavior was exploited for quantitative purposes. To investigate the detection of volatile compounds using this method, both static and flow cell-type devices were constructed. To determine the most suitable nanostructured ZnO material for the light scattering sensors, several factors that influenced their morphologies, including the calcination temperature, calcination time, and the amount of ZnO colloidal solution for calcination, were examined. Fiber-like ZnO structures were produced at temperatures below 400 C. Above 400 C, particles having round shapes were observed; the higher the calcination temperature, the larger the particle sizes. Based on an examination of the signals from several volatile organic compounds, the prepared ZnO sensor was selective for the detection of alcohols, and the observed signals followed the surface-adsorption mechanism. The prepared sensor is fast in response, and the detection time can be shorter than 2 min. For quantitative purposes, the linear range was limited to low concentrations of alcohols, i.e., up to ca. 200 ppm.

Preparation and characterization of silver film coated ZnO nanowire gas sensors based on the infrared surface enhancement effect for detection of VOCs

“…5 Since the nanoscale morphology of ZnO is small compared to IR and visible wavelengths, these nanowires exhibit characteristic absorption and scattering properties for chemical sensing by Fourier Transform Infrared Spectroscopy (FTIR). [6][7][8] Moreover, several IR reectance spectroscopy studies on ZnO have been performed previously. [9][10][11][12] In addition, in situ experiments can be performed, thus allowing the monitoring of the surface chemical modications required to increase the chemical sensing ability, for instance nanowires coated with conductive polymers, such as polyaniline (PANI), polypyrrole (PPy), polythiophene (PT), and poly(3,4-ethylenedioxythiophene) (PEDOT), have applications concentrated around gas sensing.…”