Effects of Mg doping on optical and CO gas sensing properties of sensitive ZnO nanobelts

Abstract

We report the synthesis, optical characterization and enhanced carbon monoxide (CO) gas sensing properties of magnesium (Mg) doped 1D zinc oxide (ZnO) nanobelts obtained via a vapor transport method. The structural, morphological and compositional properties of the samples were investigated by powder X-ray diffraction (p-XRD), field emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) analysis. Optical characterization was carried out using Raman spectroscopy, Photoluminescence (PL), diffuse reflectance spectroscopy (DRS), UV sensing and CO gas sensing. Crystalline nanobelts were obtained with average thickness of about 34 nm, width of 290 nm, and length of 3.25 μm. Significant changes in the bandgap energy due to Mg doping were observed. The gas sensing properties of undoped and Mg doped ZnO nanostructures were tested based on the resistance change upon exposure to air and CO gas. The ability of Mg doped ZnO nanobelts to sense 20 ppm of CO gas at 350 °C was enhanced fivefold, with good stability, indicating that Mg doping is very effective in improving the CO sensing of ZnO nanobelts. In addition, a model that describes the CO gas sensing mechanism of both undoped and Mg doped ZnO nanostructures is presented.