Polydopamine@electrochemically reduced graphene oxide-modified electrode for electrochemical detection of free-chlorine

Abstract

This paper describes the electropolymerization of dopamine on an electrochemically reduced graphene oxide (ERGO) surface that was utilized successfully for the electrocatalytic detection of free chlorine (free-Cl). ERGO was fabricated on a glassy carbon (GC) electrode by the reduction of graphene oxide (GO) using cyclic voltammetry (CV). Subsequently, the electrode (ERGO/GC) surface was electropolymerized using dopamine for 30 cycles and a polydopamine-modified electrode (PDA@ERGO/GC) was obtained. The PDA@ERGO/GC-modified electrode was characterized by field emission scanning electron microscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and CV. The surface coverage concentration (τ) of the PDA@ERGO/GC electrode was 1.70×10−10molcm−2. The presence of quinone functional groups on the electrode surface offers excellent electrocatalytic ability for the determination of free-Cl. The calculated kinetic parameters of the fabricated electrode confirmed its facile performance towards the determination of free-Cl with a rate constant (ks) and charge transfer coefficient (α) of 3.38s−1 and 0.75, respectively. Under the optimal conditions, the reduction current of free-Cl is proportional to its concentration range, 9.9–215.2μM, with a correlation coefficient of 0.998 and a sensitivity and detection limit (LOD) of 0.0071μAμM−1 and 44nM, respectively. Furthermore, PDA@ERGO/GC was used for the real sample determination of free-Cl from swimming pool water with satisfactory recoveries obtained in the range of 102.4% to 103.0%.