Reversible Switched pH-Responsive Hydroquinone Electrochemical Sensor Based on Composite Film of Polystyrene-b-Poly (Acrylic Acid) and Graphene Oxide

The detection of some environmental pollutants remains still a great challenge and the current methods suffer from low sensitivity, reproducibility and require sophisticated instruments. Here, a simple, sensitive and pH-responsive electrochemical sensor for the detection of hydroquinone (HQ) was developed based on a pH-responsive block copolymer polystyrene-b-poly(acrylic acid) (PS-b-PAA) and graphene oxide (GO) composite film (PG) modified glassy carbon electrode (GCE). The electrochemical behaviors of HQ at the modified GCE (PG/GCE) electrode were studied by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The peak current of the PG/GCE electrode toward HQ was significantly enhanced at pH 7.0 and greatly suppressed below pH 6.0, which are caused by swelling and shrinking of pH-responsive block copolymer and the synergistic effect with GO. The PG/GCE exhibited a reversible “On/Off” switch for the HQ electrochemical behaviors between pH 4.0 and pH 7.0. When the pH of the medium is 7.0, the PG complex film on the PG/GCE is in the “On” state, the linear detection range of HQ is from 16 μM to 104 μM with a detection limit as low as 0.34 μM. Furthermore, the PG/GCE can also successfully detect the HQ concentration of the lake water sample with satisfactory recovery, indicating that the pH-responsive block copolymer/GO-functionalized sensor provided a powerful avenue for simple, sensitive and convenient detection of HQ, which can be translated into practical application.