Ordered WO3-decorated ZrO2 nanotubes with efficient three-phase boundary towards highly sensitive detection of trace nitrogen dioxide

Abstract

Long-term exposure to high concentrations of nitrogen dioxide (NO₂) poses severe risks to both the environment and human health, thereby creating an urgent need for gas sensors that enable sensitive and reliable detection at relatively low operating temperatures. However, most reported NO₂ sensors still suffer from either high operating temperatures or insufficient detection sensitivity, which severely limits their practical application in atmospheric monitoring. In this study, a potential NO₂ sensor based on a ordered WO₃-decorated ZrO₂ nanotube film was fabricated via anodic oxidation and in-situ growth. The sensing properties, including a low optimum test temperature, low detection limit, high sensitivity, repeatability, and selectivity, were determined. The ordered WO₃-decorated ZrO₂ nanotube film exhibited a high NO₂ sensitivity (134.8 mV/decade) toward 0.06–10 ppm NO₂ at a medium–low working temperature of 350°C. The high performance of the sensor is primarily attributed to Knudsen diffusion in the ordered nanotube structure and the perfect three-phase boundary (TPB) of the nanocomposite, as the results indicate. This study presents a novel strategy for designing ordered nanostructures and introduces an effective approach for detecting atmospheric NO₂ concentrations.