Self‐healable, recyclable, ultrastretchable, and high‐performance NO2 sensors based on an organohydrogel for room and sub‐zero temperature and wireless operation

Abstract To date, development of high‐performance, stretchable gas sensors operating at and below room temperature (RT) remains a challenge in terms of traditional sensing materials. Herein, we report on a high‐performance NO 2 gas sensor based on a self‐healable, recyclable, ultrastretchable, and stable polyvinyl alcohol–cellulose nanofibril double‐network organohydrogel, which features ultrahigh sensitivity (372%/ppm), low limit of detection (2.23 ppb), relatively fast response and recovery time (41/144 s for 250 ppb NO 2 ), good selectivity against interfering gases (NH 3 , CO 2 , ethanol, and acetone), excellent reversibility, repeatability, and long‐term stability at RT or even at −20°C. In particular, this sensor shows outstanding stability against large deformations and mechanical damages so that it works normally after rapid self‐healing or remolding after undergoing mechanical damage without significant performance degradation, which has major advantages compared to state‐of‐the‐art gas sensors. The high NO 2 sensitivity and selectivity are attributed to the selective redox reactions at the three‐phase interface of gas, gel, and electrode, which is even boosted by applying tensile strain. With a specific electrical circuit design, a wireless NO 2 alarm system based on this sensor is created to enable continuous, real‐time, and wireless NO 2 detection to avoid the risk of exposure to NO 2 higher than threshold concentrations.