Simultaneous electrochemical deposition of an e-rGO/β-CD/MnO2 ternary composite for a self-powered supercapacitor based caffeine sensor†
A self-powered supercapacitor based on a caffeine sensor electrode has been developed using an electrochemically deposited rGO/β-CD/MnO2 ternary composite with ionic liquid assistance. This typical composite electrode was prepared from electrochemically reduced e-rGO followed by the addition of β-cyclodextrin and MnO2 from Mn(CH3COOH)2·4H2O on FTO surfaces. The composite material is indexed to the corresponding crystalline phase of MnO2 in the XRD investigation and Mn 3p, Mn 2p, C 1s, and O 1s signals were identified from XPS analysis. The cyclic voltammetry study reveals that the potential of the caffeine samples and the square wave voltammetry peak currents indicate an increasing trend for caffeine oxidation. The sensor expressed a sensitivity of 0.187 μA cm2 μM−1 with a linear range of 10–550 μM (n = 3.12). The corresponding supercapacitor also exhibited a specific capacitance of 352 F g−1 and it showed a very good life time from a long term cyclic test. The proposed ternary composite electrodes may be suitable electrodes for self-powered sensor devices.