Flake-Like WO₃-Based Thin Films for Enhanced Ethanol Sensing Applications

Abstract

Undoped and vanadium-doped tungsten trioxide (V–WO3) nanocrystalline thin films were prepared on glass substrates with the spray pyrolysis method. The synthesized films were characterized using X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM), UV-visible spectroscopy, and X-ray photoelectron spectroscopy for micro-structural, topographical, optical, and chemical properties, respectively. XRD analysis confirmed that WO3-based thin films were hexagonal phases. The FESEM images showed the interconnected nanoflake-like morphology of the undoped and V-WO3 thin films. AFM investigation confirmed that the average surface roughness of the thin films ranged from 3.36 to 14.2 nm. The optical energy bandgap of the films was estimated from the optical spectrum of absorption. The static liquid distribution method was utilized to examine the gas-sensing characteristics of deposited films. The results show that the 4wt% vanadium-doped WO3 sensor responds to ethanol vapour at room temperature. The response and recovery times towards 50 ppm of ethanol gas were determined as 32 and 21 seconds, respectively. The 4wt.% V-WO3 film has shown an increased response from 1.3 to 2.8, which is 2.15 times more than the undoped WO3.