High Sensitivity NO2 Gas Sensor Based on 3D WO3 Microflowers Assembled by Numerous Nanoplates

Tungsten oxide microflowers (WO3 MFs) were fabricated by a simple hydrothermal process through adjusting the pH of the solution by HCl. These MFs possess the outer diameters of about 2 mu m and are composed of numerous nanoplates with the average pore size of 10.9 nm. Chemiresistive activity of as-fabricated WO3 MFs sensor was attempted towards oxidizing and reducing target gases, revealing a superior selectivity to NO2 with a maximum response of 22.95 (2 ppm NO2) @ 105 degrees C compared to other target gases. One of the key features of as-fabricated WO3 MFs sensor is the lower detection limit of 125 ppb and operating temperature of 105 degrees C to NO2 with better reproducibility, signifying commercial prospective of the developed sensor materials. Finally, the gas sensing mechanism of WO3 MFs sensor has been proposed.