Temperature Tunable Selective Detection of Toluene and Isopropanol Employing Plate-Like WO3-Based Single Chemiresistor

The article reports the temperature-dependent selective detection property of plate-like tungsten oxide (WO3) toward toluene and isopropanol. A low-temperature hydrothermal method was utilized to synthesize the sensing material. An X-ray diffraction (XRD) technique and refinement study confirms the monoclinic crystal structure and a field emission scanning electron microscope (FESEM) reveals the plate-like hierarchical morphology of the synthesized material. The fabricated sensor was exposed to different volatile organic compounds (VOCs) (acetone, ethanol, toluene, isopropanol, ammonia) in the temperature range of 150 °C–300 °C. The sensor exhibited a temperature-tunable dual selectivity toward toluene at 200 °C and isopropanol at 250 °C. The sensor’s responses in the presence of 500 ppm of toluene and isopropanol at their optimum operating temperature were 10 (at 200 °C) and 12 (250 °C), respectively. Response and recovery times of the sensor for 500 ppm of analytes are around 200 and 300 s, respectively. The long-term stability of the sensor was investigated over 30 days. By adjusting the working temperature of the sensor device, the proposed sensor can detect toluene and isopropanol selectively in an indoor environment.