Hydrogen Peroxide Electrochemical Sensor Based On Carbon Quantum Dots/Metal Nanocomposites

Hydrogen peroxide is a common green oxidant in daily life.It is widely used in food,medicine,environment,biomedicine and other fields.Low concentrations of hydrogen peroxide are helpful for wound healing,but high concentrations of hydrogen peroxide are corrosive and can cause burns when it comes into contact with the skin,mucous membrane,and respiratory tract.Hydrogen peroxide is also an important intermediate product in the process of cell metabolism and one of the reactive oxygen species in human body,which is closely related to disease and human health.Therefore,realizing the effective detection of hydrogen peroxide is very important for human life.Hydrogen peroxide has electrochemical activity and can be redox on the electrode surface.This paper focuses on the electrochemical detection of hydrogen peroxide and the preparation of carbon quantum dots and their composites.The main research contents are as follows:1.Green fluorescent carbon quantum dots(CQDs)were prepared by electrochemical electrolysis with graphite rod as carbon source.The microscopic morphology,composition and formation mechanism of CQDs were studied by characterization methods such as transmission electron microscopy and infrared spectroscopy.The results show that CQDs are uniform and small spherical,with an average particle size of 7.0 nm.Its surface contains oxygen-containing functional groups such as hydroxyl and carbonyl,and has good water solubility.This method has the advantages of simple operation,low cost and relatively green.2.Carbon quantum dots-silver nanoparticle composites(CQDs-AgNPs)were prepared by chemical reduction method with ascorbic acid as reducing agent and CQDs as stabilizer and carrier.They were drop-coated on the surface of glassy carbon electrode to prepare CQDs-AgNPs/GCE.The electrochemical performance of CQDs-AgNPs/GCE for the detection of hydrogen peroxide was investigated by cyclic voltammetry and chronoamperometry.The results show that CQDs-AgNPs/GCE has good electrocatalytic activity for the reduction of hydrogen peroxide in the range of 4.00 ?mol/L ? 0.15 mmol/L and 0.15 ? 4.73 mmol/L,with a detection limit of 0.82 ?mol /L(S/N=3).The sensor is simple to prepare and has good selectivity.It can be applied to the determination of hydrogen peroxide content in contact lens care solution,with a recovery rate of 94.0% ? 100.0%.3.CoNPs-CQDs thin films were synthesized on glassy carbon electrodes by one-step electrodeposition,and a new method for sensitive detection of hydrogen peroxide was established.The morphology of CoNPs-CQDs on the modified electrode surface was investigated by scanning electron microscopy,and it was found that the particles on the electrode surface were uniform and well dispersed.Chronoamperometry studies show that under neutral conditions,CoNPs-CQDs/GCE has a fast and sensitive response to hydrogen peroxide oxidation in the range of 0.75 ?mol/L ? 1.65 mmol/L and 3.24 ? 9.14 mmol/L,the detection limit was 0.33 ?mol/L(S/N=3).The sensor has a wide linear range and good stability.It is applied to the determination of hydrogen peroxide in human serum with a recovery rate of 97.8% ? 102.5%.