Tailoring electrochemical properties of hydrogel by different types of graphene oxide

In this study, different concentrations of graphene oxides prepared according to Brodie's and Hummers' method (GOB and GOH, respectively) were integrated with mixture of citric acid and hydroxyethyl cellulose (HEC-CA). This three-component solution could be easily coated on glassy carbon electrode surface and thermally crosslinked, forming solid films of nanohybrid hydrogels (HEC-CA-GOB and HEC-CA-GOH). The coated electrodes were characterized by different electrochemical techniques, which revealed that, compared to GOB, GOH significantly hindered diffusion of electroactive species to the electrode surface. Furthermore, application of the electrodes coated with HEC-CA-GOB and HEC-CA-GOH as voltammetric detectors of toxic metals and histamine was investigated. For the former, a low amount (0.075 mg mL-1) of GOB in HEC-CA enhanced the voltammetric response towards Pb2+ and Cu2+ up to 6.5 and 10 times, respectively while effect of GOH was less sound. In histamine detection, 1 mg mL-1 GOB or GOH in HEC-CA improved the response of the electrodes towards the histamine by approximately 25 % and improved antifouling properties of the sensors. As a conclusion, adjusting of GO content in the hydrogel was shown as an interesting and facile tool for preparation of electrodes with wide range of properties adjustable such as to meet requirements of various applications.