Low-temperature and high-response nitric oxide sensor based on mesoporous WO3 microtubules inherited from absorbent cottons

The fabrication of low-temperature and high-response WO 3 -based gas sensor is very important for effective detection of hazardous nitric oxide , but the less association has been reported to date. Herein, cheap absorbent cottons were simply soaked into ethanol solution of tungsten hexachloride , and then the immersed template was calcined for preparing WO 3 materials with tubular morphology. Among, WO 3 -600 microtubules obtained by calcining at 600 °C are formed by the inter-linkage of nanoscale particles with better crystallinity , and possess small-size mesopores , low initial resistance and large specific surface area , as well as rich oxygen vacancy defects. Their synergism ensures its high sensing ability to ppb-level NO at low energy consumption. At lower 92 °C, WO 3 -600 sensor realizes a response value ( S = R g/ R a, R g and R a being the resistances in tested gas and air) of 167.1 toward 1 ppm NO gas, being higher than vast majority of reported WO 3 -based NO sensors. At the meantime, the sensor also possesses characteristics of fast recovery (13 s, the time for the change from R g to 10 % R g + 90 % R a), low actual detection concentration (50 ppb) and theoretical limit of detection (45 ppb), large sensitivity (the slope of calibration curve between sensor response and gas concentration) of 170.1 ppm −1 during 50–1000 ppb concentrations, as well as good selectivity , reproducibility, moisture tolerance and 60 days’ stability. In addition, we also analyzed the enhanced NO sensing mechanism.