Design and preparation of the WO3 hollow spheres@ PANI conducting films for room temperature flexible NH3 sensing device

The development of room temperature NH3 sensors with flexible substrate can fulfill the future demands of high NH3 sensing performance under the premise of lower energy consumption and safety circumstance in wearable electronics field. The polyaniline and a serious of WO3 hollow spheres@ polyaniline hybrid were successfully synthesized via a combined route of simple hydrothermal method and in-situ chemical oxidative polymerization. The room temperature NH3 sensors were fabricated by assembling WO3 hollow spheres@ polyaniline hybrid on flexible polyethylene terephthalate (PET) films. The NH3 sensing properties of the fabricated devices demonstrated that the device utilizing 10 mol% WO3 hollow spheres@ polyaniline (PAWHs 10) hybrid exhibited the best sensing performance to 100 ppm NH3 (response value at 25) at 20 °C. Moreover, the PAWHs10 hybrid sensor also achieved excellent NH3 selectivity, ppb-level detection limit (1.67–500 ppb NH3), and good response/recovery rates (136 s/130 s) at 20 °C. The enhanced sensing performance of incorporation of polyaniline and WO3 hollow spheres was mainly attributed to the hollow structure of WO3 and the formation of p-n heterojunction between PANI and WO3 hollow spheres.