Influence of swelling level on charge transmission of chitosan and reduced graphene oxide film electrodes

Abstract

Chitosan film (CS) and thermally reduced graphene oxide (rGO) are materials used for sensorial devices. However, the high level of swelling, characteristic of CS, coupled with unstable electrochemical measurements, reduces its application. Thus, the swelling effects of CS_rGO films obtained by CS and rGO acetic hydrogel subjected to surface neutralization with ethanol and base were investigated. Their morphological, chemical and electrochemical properties were compared. The untreated CS-rGO showed higher impedance due to the high degree of swelling that led to physical-chemical changes that compromised its efficiency. The neutralization treatments contributed to the reduction of the level of swelling and the formation of more capacitive films, preserving the electrostatic interaction between the functional groups of CS and rGO and maximizing the mobility of charges. Thus, the reduction in swelling, mainly facilitated after treatment with ethanol, presented the lowest impedance and swelling levels among all methods, being suitable for electrode compositions.