Preparation Of Several Composites Based Carbon Material And Their Application In Electrochemical Sensors

Carbon nanotubes,porous carbon materials,graphene and their derivatives possess excellent physical and chemical properties,such as excellent mechanical strength,large surface area,good conductivity and thermal conductivity.They have been widely used in the fields of energy storage,supercapacitors,electrochemical sensing and so on.Low dimensional carbon composites are based on carbon materials of different dimensions and combined with one or several other functional materials by physical or chemical methods.There is a synergistic effect existed between two kind of materials,which makes the composite has excellent comprehensive performance to meet different needs in various aspects.In this work,multi walled carbon nanotubes,porous carbon material and nitrogen doped graphene served as substrate to prepare composites via chemical reduction,hydrothermal,situ-electropolymerization and ultrasonic mixing.These composites possesses excellent electro-chemical performance.Different electrochemical sensing platform for quantitative analysis of drug molecules,environmental pollutants and small biological molecules were established based on different composite.The main contents are listed below:?1?Pd NPs/MWCNTs composite modified electrode for the detection of acetaminophenMulti-wall carbon nanotubes?MWCNTs?were carboxylated by mixed acid treatment,and then palladium nanoparticles?Pd NPs?were grown on the multi walled carbon nanotubes by chemical reduction,the final product was noted as Pd NPs/MWCNTs.The TEM and element distribution patterns of the composites showed that Pd NPs grow evenly on the surface of MWCNTs.The electrochemical performance of Pd NPs/MWCNTs/GCE was studied by AC impedance?EIS?and Chronocoulometry?CC?.The quantitative detection of acetaminophen?AP?was carried out by differential pulse voltammetry.The detection limit was 0.13?M with linear range 0.5-100?M.The constructed AP sensing platform showed good recovery in the real sample detection.It provides a reliable method for determination of paracetamol.?2?Simultaneous electrochemical sensing of hydroquinone and catechol usingnanocomposite based on palygorskite and nitrogen doped grapheneAttapulgite is a kind of natural fibrous nano-clay with porous and large specific surface area.There are a large number of hydroxyl groups on its surface which can be used as a catalytic active center.However,poor conductivity of Pal is a fatal obstacle to its further application.A suitable conductive matrix may be introduced into Pal to broaden its application in electrochemistry.Herein,We use hydrochloric acid to treat the attapulgite.After acid treatment,the specific surface area of attapulgite increased and the pore size distribution was more uniform,making it more suitable for sensor construction.Nitrogen-doped graphene?NGE?has good conductivity,it can be used as matrix that mix with attapulgite to obtain attapulgite/nitrogen-doped graphene composites.The introduction of NGE compensated for the poor conductivity of attapulgite,and the specific surface area of the copmposite increased significantly after two materials incorporation.The morphology and structure of the composite were characterized by N₂ adsorption-desorption curve,scanning electron microscopy and infrared spectroscopy.The electrochemical behavior of catechol?CT?and hydroquinone?HQ?on Pal/NGE/GCE electrode was investigated by cyclic voltammetry and differential pulse voltammetry.The results show that the oxidation peak currents of CT and HQ were proportional to the concentration in the range of 1-50?M and 2-50?M,respectively.The detection limits of CT and HQ is 0.13?M and 0.8?M,respectively.The modified electrode is easy to preparation,exhibiting high sensitivity,good stability and reproducibility.It is an economical and reliable method for simultaneous detection of HQ and CT.?3?Preparation of porous carbon based on biomass and its application in electrochemicalsensorBiomass alga was served as carbon source,porous carbon?PrC?was prepared viahydro-thermal method.The morphology and structure of PrC were observed by TEM and BET.There were plenty of pores existed observed in TEM images.PrC modified glassy carbon electrode?PrC/GCE?exhibited excellent electrochemical property dued to the large surface area and porous structure of PrC.Paracetamol demonstrated a couple of reversible redox peaks at PrC/GCE,the respond currents were enhanced significantly compared to the un-modified GCE.The experimental condition was optimized,and the electrochemical response of AP on PrC/GCE electrode was investigated by differential pulse voltammetry?DPV?..An excellent linear relationship was showed between the anode current and the concentration of AP in range 2²0?M.The LOD was calculated to be 0.35?M.In this work,the raw material was biomass alga which was easy to get and the price was low.The proposed sensor exhibited good electrochemical property and the preparation is simple,green and economy.?4?Quantitative determination of dopamine based on nitrogen doped graphene/poly-glutamate compositePoly-glutamate?PGA?film was anchored on NGE/GCE by electrochemical method to obtain PGA/NGE/GCE.NGE which modified on the surface of GCE first,can promote the polymerized process of PGA.NGE and PGA were combined by?-?interaction,synergetic effect was produced in the composite.The NGE/PGA was used in the construct of electrochemical sensor for dopamine detection.The results indicated that NGE/PGA modified electrode showed higher response current and better catalytic ability than single component modified electrode.PGA/NGE/GCE was used for quantitative determination of dopamine under optimal experiment conditions.LOD was 0.2?M and the detection range was 0.2?M²0?M,20?M⁵0?M.Moreover,PGA/NGE/GCE demonstrated excellent selectivity,stability and repeatability.