Non-enzymatic hydrogen peroxide sensor based on graphene quantum dots-chitosan/methylene blue hybrid nanostructures

Graphene quantum dots (GQDs) functionalized with chitosan (GQDs-CS) were used for the first time as a suitable nanostructured sensing film for efficient immobilization of methylene blue (MB) through aminohydroxyl reaction to prepare a novel non-enzymatic hydrogen peroxide sensor using a glassy carbon electrode (GCE). The synthesized hybrid nanostructures were characterized by X-ray diffraction, field emission scanning electron microscopy, cyclic voltammetry, FT-IR, UV-vis, photoluminescence, and energy dispersive X-ray spectroscopy techniques. Cyclic voltammograms showed that the GQDs-CS/MB/GCE exhibited a significant electrocatalytic activity for the reduction of H2O2. The calculated k(cat) is 4.45 x 10(4)cm(3)mol(-1)s(-1). The calibration graph for H2O2 constructed by amperometry (-0.6 V vs. SCE) at the modified electrode showed two different linear ranges (1.0 x 10(-6)-2.9 x 10(-3)M and 2.9-11.78 mM) with a sensitivity of 10.115 mu A/mM for the lower linear range and a calculated detection limit of 0.7 mu M (S/N = 3). The response time of the sensor for H2O2 detection was 3s. The electrochemical response of GQDs-CS/MB/GCE is not influenced by potential interferents (ascorbic and uric acids, dopamine, caffeine, glucose, and various inorganic salts). This modified electrode exhibited suitability for the non-enzymatic H2O2 sensing in food and water samples. (C) 2017 Elsevier Ltd. All rights reserved.