Cu/SnO2 gas sensor fabricated by ultrasonic spray pyrolysis for effective detection of carbon monoxide

Abstract

In this paper, we report results of morphological, structural, optical analysis of ultrasonically sprayed Cu-doped SnO2 thin films and their applications in conductometric gas sensors to detect small traces of CO molecules. Effects of Cu-doping on morphological, structural and optical properties of SnO2 nanostructures were investigated by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and UV-Vis. Spectroscopy measurements. Scanning electron microscopy revealed that porosity of the film surfaces is increased with increasing Cu-doping. From the XRD patterns, the size of the crystallites and crystal quality of the films are found to be decreased with Cu-doping. UV-Vis. spectroscopy results presented that the transmittance and bandgap can be manipulated with Cu-doping where both are decreased with Cu-doping. The relation between morphology and structure of the films with CO response properties are discussed properly. The gas response of the films with different Cu-doping has been investigated at different CO concentrations at different operating temperatures. From the sensing measurements, it is found that Cu-doping improves the SnO2 based sensor response to CO gas. Furthermore, the possible sensing mechanism to enlighten the improved gas sensing behavior of the films is proposed.