Enhanced gas sensing performance of sprayed ZnO–ZnWO4 toward CO gas

Abstract

Composite ZnO–ZnWO₄ films were obtained by a cost-effective chemical spray pyrolysis approach on a glass substrate using zinc chloride and ammonium metatungstate as starting precursors. The X-ray diffraction investigation indicated that the crystal structure of the obtained films was a composition of ZnO and ZnWO₄ phases with the predominant ZnWO₄ phase. Scanning electron microscopy images for sprayed mixed ZnO–ZnWO₄ layers exhibit a porous structure. Gas sensing performance was tested for detecting carbon monoxide (CO) at different operating temperatures. It was found that the sprayed composite ZnO–ZnWO₄ layer shows a maximum sensitivity of 422.7% for 30 ppm CO at 250 °C with good sensor performance. This study suggests that the sprayed ZnO–ZnWO₄ composite layer is a good candidate material for CO detection at a relatively low operating temperature.