Performance analysis of Fe2O3/CNT humidity sensor based on adsorption kinetics and DFT computations

Abstract

Low sensitivity, long recovery times and unstable ability at high humidity has become a problem to develop humidity sensors. To overcome these problems, iron sesquioxide/carbon nanotube (Fe2O3/CNT) composite was prepared by hydrothermal technique as the humidity sensor material. The results of XRD and FI-IR reveal that Fe2O3/CNT with abundant hydrophilic functional groups are successfully synthesized. Meanwhile, First-principles (DFT) results demonstrate that Fe2O3 has higher binding energy and density of states (DOS) peak shift when worked with water molecules than ferric oxide (Fe3O4), indicating it has better adsorption kinetics thus to high humidity sensitivity on the surface. Furthermore, the capability of the Fe2O3 material to sense humidity was investigated via hysteresis and response/recovery test. Based on the hydrophilic functional groups and high adsorption capacity for water molecules, when compared with Fe3O4-based humidity sensor, this Fe2O3/CNT device has an excellent humidity sensitivity, which display low hysteresis, good repeatability, and short response time. This work suggests that Fe2O3/CNT could be a promising candidate material for developing high-performance humidity sensor.