A novel enzyme-free amperometric sensor for hydrogen peroxide based on Nafion/exfoliated graphene oxide-Co_3O_4 nanocomposite

摘要

Electrochemical detection of H_2O_2 was investigated on a Nafion/exfoliated graphene oxide/Co_3O_4 nanocomposite (Nafion/EGO/Co_3O_4) coated glassy carbon electrode. The morphological characterization was examined by scanning electron microscopy,X-ray diffraction,and electrochemical impedance spectroscopy. The modified electrode showed well defined and stable redox couples signal in both alkaline and natural aqueous solutions with excellent electrocatalytic activity for oxidation of hydrogen peroxide. The response of the modified electrode to H_2O_2 was examined using amperometry (at 0.76 V vs. Ag/AgCl reference electrode) in a phosphate buffer solution (pH 7.4). The detection limit was 0.3 mmol L~(-1) with a linearity of up to four orders of magnitude and a sensitivity of 560 μA mmol~(-1) Lcm~(-2). The response time of the electrode to achieve 95% of the steady-state current was recorded at 4 s. The ability of the sensor for routine analyses was demonstrated by the detection of H_2O_2 presents in milk samples with appreciable recovery values. In addition,the Nafion/EGO/Co_3O_4-GCE showed good selectivity for H_2O_2 detection in the presence of ascorbic acid, uric acid, and glucose. The attractive analytical performances such as remarkable catalytic activity, good reproducibility, long term stability, and facile preparation method made this novel nanocomposite electrode promising for the development of effective H_2O_2 sensor.