High-performance and wearable hazardous gases sensor based on n-n heterojunction film of NGO and tetrakis(1-pyrenyl)porphyrin.

The popularity of "Internet of Things" and portable electronic devices creates unprecedented demands for wearable gas sensors with excellent performance. In this study, the flexible n-n heterojunction film is firstly produced from metalloporphyrin complex 5,10,15,20-tetrakis(1-pyrenyl) porphyrin cobalt (II) (CoTPyrP) and nitrogen-doped graphene oxide (NGO) film, using solution-processing quasi-Langmuir-Shäfer (QLS) method and employed as the electrochemical identification layer for the wearable sensor. Thanks to the attractive electron-transfer properties from porphyrin to NGO, and the local regulation of electron transport by N and C atoms with different electronegativity on NGO, the resulting sensor shows good responses to NO2, SO2, NH3, H2S gases with the low detection limit (LOD) of 6, 74, 113 and 178 ppb, respectively. The uniform and compact structure of the heterojunction films provide excellent mechanical flexibility and suppress the penetration of gases into the film to obtain fast recovery speed. In addition, a sensor array consisting of NGO/CoTPyrP heterojunction and CoTPyrP film sensor is established, achieving selective identification of four hazardous gases. The present work provides potential application for hazardous gases identification in actual systems, and proposes an effective method to develop new flexible n-n heterojunctions for wearable gas sensors.