MXene/Polypyrrole-Based Fibrous Sensor for Wearable Sensitive Ammonia Detection

It is highly desirable to develop high sensing performance polypyrrole (PPy)-based NH3 sensors with excellent portable properties, including lightweight, flexibility, and high integrability. In this work, we developed a fibrous PPy-based NH3 sensor through forming the MXene/PPy hybrid sensing material (with loadings of 0.2 mg/m MXene and 2 mg/m PPy) onto a regenerated cellulose yarn substrate (RC+@MXene/PPy yarn) by a self-assembling and in situ polymerization strategy. The chemical modification method of the regenerated cellulose yarn is developed to guarantee the strong adhesion between the MXene nanosheets and the substrate, thereby preserving the formation of the interfacial heterojunction and large surface area of the MXene/PPy sensing material. This structural integrity contributes to the obtained RC+@MXene/PPy composite yarn with significantly superior sensing performances compared to other existing PPy-based NH3 sensors, including high sensitivity (a high response of 320% at 100 ppm of NH3) and low trace levels of NH3-monitoring capability (50 ppb). Taking advantage of the great sensing performance and superior flexibility of the RC+@MXene/PPy yarn, we fabricated various wearable devices for sensitive ammonia monitoring, including early ammonia leakage detection, food spoilage warning, and non-invasive disease diagnosis.