Highly sensitive In2O3/PANI nanosheets gas sensor for NO2 detection

Abstract

Indium oxide (In2O3) gas sensors are regarded as one of the potential materials for detecting and quantifying hazardous gases for monitoring systems and public safety assurance to address the severe environmental problems plaguing our civilization. In this work, In2O3/PANI composites were synthesized using the hydrothermal technique to explore nitrogen dioxide (NO2) sensing capabilities. The scanning electron micrographs (SEM), crystal structures (XRD), energy dispersive X-ray analysis (EDS), and the gas sensing properties were investigated to ascertain the morphology, purity, response/recovery time, optimal temperature, and recyclability. The samples displayed a gas-accessible structure with stacks of several porous nanosheets. The as-synthesized In2O3/PANI-1 sensors have extremely high responses (341.5 @ 30 ppm, 12.8 @ 3 ppm) to NO2 gas at a working temperature (250 °C), quick response times (24 s @ 30 ppm, 47 s @ 3 ppm) and recovery times (53 s @ 30 ppm, 74 s @ 3 ppm), and a low detection limit (300 ppb). Following a series of testing, high repeatability and selectivity were obtained. Furthermore, the In2O3/PANI sensor's fundamental detecting mechanism for NO2 gas was completely discussed. In addition, a developed mechanism defining the performance of the nanosheet-based sensors in NO2 gas is shown, which is backed by density functional theory (DFT) calculations to investigate the electrical characteristics of In2O3/PANI composites. This work offers an intriguing perspective as well as a useful strategy for fabricating long-lifetime In2O3-based nanosheets using the hydrothermal process.