Comprehensive analysis of reaction mechanisms in reduced graphene oxide and hematite heterostructure gas sensors

Exposure to formaldehyde (HCHO) in humans causes various types of diseases, such as asthma, lung cancer, and nasal cancer depending on the exposure, which leads to death in severe cases. Many types of gas sensors are being studied in order to sense HCHO, but the sensors cannot detect below the WHO standard of 0.08 ppm. We present a highly sensitive and inexpensive HCHO gas sensor with a heterostructure of reduced graphene oxide (rGO) and hematite (Fe2O3) in this study. In addition, rGO and Fe2O3-based gas sensors are prepared in order to compare the response characteristics with the proposed heterostructure-based gas sensor. As a result, we observed a high response of 309 % for an HCHO of 100-ppm, which is 10 times higher compared to the reference sensors. We also addressed a neural network analysis to predict the response characteristics of the unmeasured HCHO concentration, and we obtained the highest accuracy, which was above 90 %, when we used the sigmoid model-based neural network model. These results facilitate the realization of ultra-sensitive gas sensors to HCHO gas, which lead to prevent various types of diseases.