Room temperature operable solid-state sensors for selective methanol vapour detection from orthorhombic WO3 nanoplates

Facile hydrothermal synthesis of tungsten oxide (WO3) has been successfully done without using any surfactant. The average crystallites size and band gap were calculated as 24 nm and 2.60 eV, respectively. During the selectivity analysis, WO3-based sensor possessed the highest response towards methanol among various volatile organic compounds (VOCs) (methanol, ethanol, isopropanol, acetone and toluene) at room temperature. The response of the sensor towards methanol was calculated to be 1.35, 1.85, 3.00, 4.85 and 12.77 at 20 ppm, 50 ppm, 100 ppm, 300 ppm and 500 ppm respectively. The response and recovery time was calculated as 8.70 s and 3.22 s respectively at 500 ppm. The sensor's response was also investigated under various relative humidity (RH) environments of 33 %, 44 %, 54 %, 75 %, 97 %. It was found that the response gets decreased with increased RH. After 20 days of observation, very low decrease (from 12.77 to 10.99) was observed in response.