Enhanced humidity sensing of functionalized reduced graphene oxide with 4-chloro-3-sulfophenylazo groups
School of Engineering
Humidity sensing material plays an important role in developing efficient humidity sensors. In this paper, reduced graphene oxide grafted by 4-chloro-3-sulfophenylazo groups (rGO-SC) was synthesized. Microstructure of rGO-SC was similar to that of rGO. Humidity sensors fabricated by rGO-SC exhibited three orders of magnitude change of its impedance, a high sensing response value (S = 2961.39), short response/recovery time (1.3 s / 23.5 s), and a small hysteresis (4.56%). A synergistic effect arising between sulfonic acid and Cl groups on rGO-SC surfaces improved the humidity sensing properties of the material. Experimental results showed that the humidity sensing of the rGO-SC was attributed to electronic or ionic conductivities at varying relative humidity, respectively. © 2019 Elsevier B.V.