A novel impedimetric humidity sensor based on a one dimensional [Pb0.5(TAA)]n (HTAA = 3‑thiopheneacetic acid) coordination polymer

Abstract

Recently, coordination polymers (CPs) have been proved to be promising candidates to construct humidity sensors mainly based on signal transduction of optical and mechanical manners, however the electrical sensors are still limited, especially the impedance type ones with advantages of simple circuit, cheap equipment, real-time monitoring, and high sensitivity. In this work, a lead containing CP with the formula of [Pb0.5(TAA)]n (noted as PbL, HTAA = 3‑thiopheneacetic acid) was obtained under hydrothermal conditions. The PbL CP possesses a novel one dimensional (1D) [PbOPb]n chain along this structure. Considering the [PbOPb]n chain and numerous activity sites (Pb cations, oxygen atoms, sulfur atoms), the PbL CP was employed as a humidity sensing film in an impedimetric sensor. The item product of PbL exhibited superior humidity sensing performance, including high sensitivity, fast response, narrow hysteresis and good repeatability. Moreover, the corresponding humidity sensing mechanism was discussed through the complex impedance spectra (CIS) as well, which confirmed great contributions to conduction by distinct charge carriers at different moisture contents. This work may provide an ideal candidate for impedimetric humidity sensors, and further develops a new promising application for CPs in electrical sensory devices.