Impedometric phenol sensing using graphenated electrochip

The manuscript reports impedance based sensing of phenol using electrochemically reduced graphene oxide (E-rGO) modified screen printed electrode (SPE). The chemically synthesized graphene oxide (GO) was reduced electrochemically directly on the electrode surface. The E-rGO was characterized using various analytical techniques like UV–vis spectroscopy, Transmission electron microscopy (TEM), Atomic force microscopy (AFM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and contact angle measurement, to get insight to its properties. The SPE/E-rGO was then used for the detection of phenol using impedance spectroscopy. Prior to impedance based phenol sensing, the mechanism of phenol oxidation was examined using differential pulse voltammetry (DPV), which showed presence of three well defined peaks at 0.62 V, 0.24 V & 0.004 V, corresponding to the oxidation of phenol, and its oxidation products. As a function of phenol concentration, the increase in oxidation current followed the linear equation having slope of −1.76 × 10 −9 A/μM and intercept of −4.69 × 10 −7, with regression coefficient of 0.996. For impedometric sensing, change in polarization resistance with change in phenol concentration was used as a signal and the dynamic linearity range was obtained from 1 μM to 40 μM. The linearity curve exhibited slope of −7.6 Ωcm −2 μM −1, intercept of 986.67 and regression coefficient (R 2 ) of 0.989 respectively. The effect of solution pH on impedometric response of graphenated electrochip was also evaluated. The impedometric results of phenol sensing were further validated using amperometery using same concentration range (1 μM to 40 μM) of phenol. The amperometry results obeyed the linear equation with slope of −0.06 A/M (ampere/molar), intercept of −13.98, and regression coefficient (R 2 ) of 0.99. The graphenated electrochip exhibited good reproducibility and selectivity towards the analyte and offers greater ease of use.