Modified graphene oxide/Nafion composite humidity sensor and its linear response to the relative humidity

Graphene oxide (GO) and its derivatives have attracted great interests in humidity sensing area for its unique 2D structure and excellent hydrophilic property. But the stability is unsatisfactory. Besides, the long-term linearity is seldom studied. In this work, diamine modified GO (MGO) has been synthesized and mixed with Nafion polymer to form a hybrid film, and applied to the humidity sensors. Both MGO and its composite show good sensitivity to the relative humidity (RH). The addition of Nafion decreases the charge transfer resistance (Rct) and increase the sensitivity of MGO based sensor. Linearity of the sensor is improved by the combination of MGO and Nafion. Long-term testing results show the linearity of the composite sensors changes over time but always keeps a better linearity than the pure MGO sensor.