Influence of sol concentration on CdO nanostructure with gas sensing application

The effect of sol concentration has been investigated on the sol-gel derived CdO nanostructures to optimize the optical and electrical properties enhancing gas sensing properties at low temperatures. X-ray diffraction patterns show that 0.5 M CdO film has cubic structure (111) preferred orientation with 34 nm particle size. Scanning electron micrographs indicated concentration dependent surface morphology. The optical band gap energy for highly transparent thin films increases from 1.9 eV to 2.34 eV as molarity was increased from 0.2 M to 1.0 M. The photoluminescence spectra of the samples have a violet to blue emission peak centred at 435 nm. J-V characteristics show that thin film of 0.5 M has conductivity 1.41 x 10(-3) S/m. The sensor characteristic such as response curve, sensor response, response time and recovery time were measured for optimized thin film at different operating temperatures. The sensor response was found 20% near room temperature (32 degrees C) and proportional to temperature. Fastest response time 10s and recovery time 20s were observed near room temperature. The resistivity of sensor was found to decrease in presence of gas attribute to more charge carriers with flower like morphology. Our study is encouraging to get faster response by CdO thin films near room temperature. (C) 2017 Elsevier B.V. All rights reserved.