Room temperature mixed-potential solid-electrolyte NO2 sensor for environmental monitoring

Abstract

Mixed-potential solid-electrolyte (MPSE) gas sensors have important applications for the detection of hazardous NO2. However, limited by the poor conductivity of conventional electrolytes at low temperatures, the realization of high performance of MPSE gas sensors usually requires a compromise to high working temperatures, hindering their application. To this end, we developed a novel ultrasensitive and selective MPSE NO2 sensor based on K2Fe4O7 solid electrolyte and Ni-MOF|N2 sensing electrode (SE), which can achieve a low detection limit (LOD) as low as 5 ppb at room temperature (RT) without additional energy supply. Simultaneously, the selectivity of the sensor to the interfering gas NO achieves a 31-fold improvement by the enhanced participation of H2O molecules and unsaturated coordinated Ni ions, which are obtained by the sintering in anoxic atmospheres like N2 or Ar. Moreover, the sensor is further used as the information collection terminal of the Internet of Things (IoT) system, building a NO2 monitoring network for remote monitoring, different environment evaluation, and information sharing. This work fills the gap of the ultrasensitive MPSE NO2 sensor in the RT field and provides new insights for the construction of NO2 portable sensor networks.