Flexible carbonized cotton/thermoplastic polyurethane composites with outstanding electric heating and pressure sensing performance

Although flexible wearable conductive textiles for various applications have attracted great attention from researchers in recent years, it is still a great challenge to fabricate conductive textiles with the advantages of a simple fabrication process, excellent flexibility, environmental friendliness, and superior performance. Carbonized cellulose materials are gradually emerging in flexible electronics due to their flexibility, low cost, abundant raw materials, and electrical conductivity. Herein, carbonized cotton fabrics were fabricated from cotton fabrics via a simple carbonization process. Then carbonized cotton/thermoplastic polyurethane composites, with excellent electric heating performance and pressure sensing performance, were fabricated through a dip-and-dry method. Carbonized cotton/thermoplastic polyurethane composites show satisfactory electrical conductivity, electric heating temperature rising performance, heating stability, and resistance stability. The surface temperature of carbonized cotton/thermoplastic polyurethane composites can reach ≈53°C within 1.5 min at 5 V. Besides this, the fabricated flexible pressure sensor based on carbonized cotton/thermoplastic polyurethane composites exhibits the combined superiority of a wide working range (0–16 kPa), high sensitivity (98.77 kPa−1), and excellent durability (>4000 cycles). Moreover, the finger motions and wrist pulse can be monitored in real time. These results demonstrate the potential application value and broad developmental prospects of carbonized cotton/thermoplastic polyurethane composites in flexible wearable electronics.

Electrospun Cu-doped In2O3 hollow nanofibers with enhanced H2S gas sensing performance

One-dimensional nanofibers can be transformed into hollow structures with larger specific surface area, which contributes to the enhancement of gas adsorption. We firstly fabricated Cu-doped In2O3 (Cu-In2O3) hollow nanofibers by electrospinning and calcination for detecting H2S. The experimental results show that the Cu doping concentration besides the operating temperature, gas concentration, and relative humidity can greatly affect the H2S sensing performance of the In2O3-based sensors. In particular, the responses of 6%Cu-In2O3 hollow nanofibers are 350.7 and 4201.5 to 50 and 100 ppm H2S at 250 °C, which are over 20 and 140 times higher than those of pristine In2O3 hollow nanofibers, respectively. Moreover, the corresponding sensor exhibits excellent selectivity and good reproducibility towards H2S, and the response of 6%Cu-In2O3 is still 1.5 to 1 ppm H2S. Finally, the gas sensing mechanism of Cu-In2O3 hollow nanofibers is thoroughly discussed, along with the assistance of first-principles calculations. Both the formation of hollow structure and Cu doping contribute to provide more active sites, and meanwhile a little CuO can form p—n heterojunctions with In2O3 and react with H2S, resulting in significant improvement of gas sensing performance. The Cu-In2O3 hollow nanofibers can be tailored for practical application to selectively detect H2S at lower concentrations.