The Synthesis Of Heteroatom-doped Carbon Nanomaterials And Applications Of Their Electrochemical

In recent years,graphene has been paid much attention in electrochemical sensor,electrocatalysis area because of its outstanding chemical and physical properties,such as large specific surface area,high efficient electrical transmission,excellent electrocatalytic activity,etc.However,the application of graphene was limited by its poor dispersion in water due to the Vander Waals interaction.Thus,the modification or functionalization of graphene or graphene oxide by various methods has become a research hotspot.Doping can change the structure of graphene electronics and it is one of the convenient ways to increase graphene's conductivity.In this paper,nitrogen-doped graphene and the composite material of nitrogen-doped graphene and metal nanoparticles are explored to apply in electrochemical sensor.The main contents were as follows:(1)Nitrogen-doped graphene(denoted N-RGO)was prepared by reducing the mixture of graphene oxide and ammonia with hydrazine hydrate.The synthesized nitrogen-doped graphene was characterized by transmission electron microscopy(TEM),fourier-transform spectroscopy(FTIR),X-ray diffraction(XRD),X-Ray photoelectron spectroscopy(XPS),and the results showed that the nitrogen doping amount was 1.8%.N-RGO modified glassy carbon electrode(NRGO/GC)was explored for the simultaneous determination of hydroquinone(HQ)and catechol(CC)using cyclic voltammetry and differential pulse voltammetry.The potential separation of the oxidation peaks between hydroquinone and catechol was up to 110 mV,which is enough to electrochemical distinguish the dihycroxybenzene isomers.The oxidation peak currents of hydroquinone and catechol linearly increased with the concentration in the ranges of 5-693 and 5-492 ?mol/L,respectively.The detection limits of hydroquinone and catechol were 0.1 ?mol/L and 0.5 ?mol/L,respectively.When simultaneously changing the concentration of the two isomers,the linear range was from 15 to 330 ?mol/L for both HQ and CC.The relative standard deviations(n=20)are 3.45% for HQ and 3.82 % for CC.(2)Uric acid(UA)and xanthine(Xa)were simultaneously determined using chitosan/N-RGO modified glassy carbon electrode(Chitosan/N-RGO/GC).Uric acid and xanthine are electrochemical oxided at 0.3 and 0.7 V(vs.AgCl/Ag),respectively.Under the optimized conditions of 0.1 ?mol/L phosphate buffer(pH 7.0),the oxidation peak current of uric acid and xanthine increased linearly with the increaseof concentration in the range of 5-340 and 10-300 ?mol/L.The detection limits for uric acid and xanthine were 0.30 ?mol/L and 0.25 ?mol/L,respectively.(3)Au-Pd/N-RGO was synthesized by "one-pot" method using caffeine as the structure-directing agent.Au-Pd/N-RGO modified glassy carbon electrode is studied for the determination of environmental pollutants hydrazine hydrate.Under the conditions of 0.1 mol/L phosphate buffer(pH 5.91),the oxidation peak current of hydrazine hydrate increased linearly with the increase of concentration in the range of30-200 ?mol/L,and the detection limit was 2.0 ?mol/L.