Improving anti-humidity property of In2O3 based NO2 sensor by fluorocarbon plasma treatment

A strategy in solving moisture interference is proposed by coating hydrophobic fluorocarbon on metal oxide sensors.The CF layers largely enhance the anti-humidity performance of In2O3 sensor, the response only varies 3.7% in high humidity.The sensor presents excellent sensitivity, stability and rapid response/recovery rates in high humidity. Nitrogen dioxide (NO2) is one of the most dangerous pollutants, which extremely hazard our health and live environments. In2O3 based chemiresistive gas sensors have been widely applicated to detect NO2 because of their excellently selectivity and highly sensitivity. However, the performances of In2O3 based NO2 sensors are greatly perturbed by ambient moisture, which greatly limits their practical applications. In this work, because of the unique low surface energy and hydrophobic characters of fluorocarbon (CF), a layer of CF is modified on In2O3 by CF plasma treatment to improve their anti-humidity properties in NO2 sensing. The gas sensing performance measurements demonstrate that the CF modified In2O3 (CF-In2O3) sensors show good sensitivity and selectivity to NO2. Most importantly, the modification of CF layer can largely enhance the anti-interference performance of CF-In2O3 sensor to humidity; the response varies only 3.7 % (CV) in high humidity environment. Furthermore, the mechanisms of gas sensing and anti-interference to humidity have been explained based on the experimental results. This work makes a great advance in solving moisture interference and also makes a great significant to detect NO2 in practical application.