Electrochemical Sensors Based On Graphene Nanocomposite For Determination Of Phenolic Compounds-catechol, Hydroquinone, Acetaminophen And P-aminophenol

As two positional isomers of phenolic compounds,hydroquinone and catechol are used in many fields,such as cosmetics,antioxidants,flavors,photography,dyes,pesticides,medicines,and pharmaceutical industries.However,due to the low degradability and high toxicity in the ecological system,and similar chemical structure and coexistence,they are highly toxic to living beings.As an analgesic and antipyretic drug,paracetamol（N-acetyl-p-aminophenol or acetaminophen）is mainly used for the reduction of fever and relief the pain associated with headache,arthritis,postoperative pain and backache.However,the accumulation of acetaminophen may cause severe and sometimes fatal hepatoxicity,such as,the toxic side effects of the liver,the kidneys,the blood system and the nervous system.As a synthetic intermediate or degradation product of paracetamol,the accumulation of4-Aminophenol has significant nephrotoxicity and teratogenic effect.Therefore,it is essential to develop simple,sensitive and accurate analytical methods for the detection of hydroquinone and catechol,4-Aminophenol and paracetamol.Among many other methods,electrochemical sensors have attracted significant interests owing to their excellent sensitivity and cheap equipment in this field,especially for electrochemical sensors based on nanomaterials.As a new nanomaterial,graphene has attracted wide spread attention because of its unique structure,excellent chemical and physical properties.In this paper,the electrochemical sensors were fabricated based on graphene composite and used to detect hydroquinone and catechol,4-Aminophenol and paracetamol.In addition,the proposed methods which possess good performance were applied successfully to the simultaneous determination of hydroquinone and catechol,4-Aminophenol and paracetamol in real samples with satisfied results.The main works are as follows:1.Determination of catechol based on gold/Ni（OH）₂ nanocomposites supported on reduced graphene oxide via one-step wet-chemical methodHere,the gold/Ni（OH）₂ nanocomposites supported on reduced graphene oxide（Au/Ni（OH）₂/rGO）were synthesized via one-step wet-chemical method,which were characterized by transmission electronmicroscope,fourier infrared spectrometer,scanning electron microscope,X-ray photoelectron spectroscopy and X-ray powder diffractometer.And the nanocomposites modified electrode was prepared by modifying the material on the glassy carbon electrode,which possessed excellent electrocatalytic activity to the redox reaction of catechol.Under the optimal conditions,the concentrations of catechol gave a linear relation with its response current from 0.40μM to 33.80μM with a detection limit（S/N=3）of 0.13μM.This sensor with excellent selectivity and sensitivity can be applied to detect catechol in water with pleased results.2.Simultaneous determination of hydroquinone and catechol using a glassy carbon electrode modified with Au@Pd loaded on reduced graphene oxideAu@Pd core-shell nanoparticles were synthesized successfully through the heterogeneous,epitaxial growth of Au on Pd nanoplates.The Pd nanoplates were prepared by reducing H₂PdCl₄ with polyvinylpyrrolidone,which served as seeds for the nucleation of Au atoms formed by reducing HAuCl₄with citric acid.Characterization of the as-prepared Au@Pd nanoparticle by scanning electron microscopy reveals that Au shell was formed around the Pd nanoplate.In order to avoid the agglomeration,the Au@Pd nanoparticles were loaded on the reduced graphene to give Au@Pd/rGO nanohybrid which exhibited excellent electrocatalytic activity toward the redox of hydroquinone and catechol simultaneously.The linear detection ranges were 0.01⁴00.00μM for hydroquinone and 0.10⁴00.00μM for catechol,with the detection limits of 0.01μM for hydroquinone and 0.10μM for catechol.Because of the excellent performance of lower detection,wider linear range and better selectivity,the prepared Au@Pd/rGO nanohybrid has potential applications in the electrochemical sensing field.3.Electrochemical sensor based on palladium-reduced graphene oxide modified with gold nanoparticles for simultaneous determination of acetaminophen and 4-aminophenolHerein,a newly developed electrochemical sensor based on the nanohybrid of palladium-reduced graphene oxide modified with gold nanoparticles（Au/Pd/rGO）was established,which was prepared by electrodepositing Au nanoparticles on Pd/rGO modified glass carbon electrode.The morphologies and microstructures of the as-prepared nanohybrid were characterized by X-ray photoelectron spectroscopy,Scanning electron microscopy and Infrared spectroscopy.And,experiment results showed that the prepared Au/Pd/rGO nanohybrid exhibited excellent electrocatalytic activity toward the redox of acetaminophen and4-aminophenol simultaneously.The linear detection ranges were 1.00²50.00μM for acetaminophen and1.00³00.00μM for 4-aminophenol,with the detection limits of 0.30μM for acetaminophen and 0.12μM for 4-aminophenol,respectively.The sensor can be used for the determination of acetaminophen in real medicine,the result is accuracy.Because of the excellent performance of lower detection,wider linear range and better selectivity,the prepared Au/Pd/rGO nanohybrid with more potential applications was a promising candidate for advanced electrode material in electrochemical sensing field.