Preparation, characterization and sensing properties of WO₃-deposited over LED

Tungsten oxide (WO₃) nanoparticles were successfully deposited by the SILAR technique on the commercially available light-emitting diode (LED) with a wavelength of approximately 370–400 nm. X-ray diffraction (XRD) studies confirmed the thermally stable monoclinic phase of deposited WO₃, and morphological analysis showed the formation of nanoparticles with pores and voids which are essential to improve the overall sensing performance of the WO₃. The sensing characteristics of prepared WO₃ were tested, and WO₃ showed a better response towards 20 ppm of formaldehyde vapor. The formaldehyde response was doubled along with less response time under the LED illuminated condition. The WO₃ is highly selective to formaldehyde under a mixed vapor environment. The response and recovery time was found to be 32 s, and 38 s was achieved under the LED illuminated state. The role of light energy in increasing the concentration of reactive site was discussed, and a photo-assisted formaldehyde detection mechanism of WO₃ was proposed and discussed.