Preparation And Electrochemical Application Of Novel Carbon Based Composites

In recent years,novel carbon based materials with their excellent properties such as large specific surface area,good electrical conductivity and so on have attracted attention,which has greatly promoted the development of society.Graphene and nitrogen doped porous carbon,as two representative carbon based materials,are widely used in the field of energy systems,materials and environmental detection.In view of the above reasons,firstly,we used reduced graphene as the carrier to prepare manganese doped nanocomposites,which were successfully used for water splitting and improve energy utilization.Secondly,a series of electrochemical enzyme-free sensors were prepared by using the novel nitrogen doped porous carbon as the carrier to detect hydrogen peroxide,hydrazine,dopamine,ascorbic acid,uric acid and other important analytical substances.In the introduction part,the preparation methods,sources and application of novel carbon based materials in recent years are introduced.The main part of the articles mainly includes the following five aspects:(1)The development of oxygen evolution reaction(OER)electrocatalysts with low-cost and high efficient for renewable energy systems is very essential.Layered double hydroxides have been confirmed as the promising candidates for OER.Nevertheless,intrinsically inferior properties of layered double hydroxides inhibit the electrocatalytic activity for OER.Herein,the Mn-doped Ni Fe layered double hydroxide(Ni Fe LDH)/reduced graphene oxide(Mn-Ni Fe LDH/r GO)is designed by a facile hydrothermal approach,which exerts outstanding OER activity and durability.Remarkably,the optimal Mn-Ni Fe LDH/r GO composite shows the enhanced the OER performances with the ultralow overpotential of 256 m V@10 m A?cm^-2,Tafel slope of40.0 m V?dec^-1 and excellent stability.Such superior OER activity is comparable to these of recently reported state-of-the-art OER catalysts.This work provides a strategy for the rational design of highly active,durability and low cost electrocatalysts for energy conversion applications.(2)In this chapter,dopamine hydrochloride and manganese acetate were used as precursors for prepared successfully the manganese ion precursor doped with dopamine at room temperature under alkaline conditions.Then the manganese oxide doped dopamine derived nitrogen doped porous carbon(Mn O@DNPC)was successfully prepared by high temperature carbonization nanocomposites.The morphology and properties of these materials were characterized by BET,TEM and XRD.The electrocatalytic properties of the composite materials were investigated by cyclic voltammetry in detail.The effects of different amount of manganese,calcination temperature,and the catalytic effect of composite materials in different potential ranges on hydrogen peroxide were also explored.The experimental results show that compared with Mn O and DNPC,Mn O@DNPC composite modified electrode has a higher catalytic effect on hydrogen peroxide.Under the optimized experimental conditions,the linear range of H₂O₂ in the reduction potential range was 30?6380?m with the detection limit of 0.013?m(S/N=3),and the linear range of oxidation potential was 20?4190?m with the detection limit of 0.01?m(S/N=3).In addition,the composite materials modified electrode had good stability,repeatability and selectivity for the determination of H₂O₂,which may be successfully used for the determination of H₂O₂ in some actual samples.(3)Nitrogen doped porous carbon(NPC)derived from ZIF-8 was successfully prepared through organic solvent method in normal temperature and high temperature carbonization method.After that,silver nanoparticles were effectively coated on the NPC by simple electrochemical reduction method.At the same time,the electrochemical reduction response of H₂O₂ on composite materials modified glass carbon electrode was detected by cyclic voltammetry.The result proved that comparing with bare GCE,silver nanoparticles modified GCE,NPC modified GCE,Ag NPs@NPC modified electrode showed an excellent electrocatalytic activity towards H₂O₂ with stronger current response and higher reduction potential own to good conductivity of NPC substrate and fast electron transfer of silver nanoparticles.Under the appropriate experimental conditions,the result of electrochemical measurement showed a wider linear range of 2?1868?M and a lower detection limit of 0.054?mol/L(S/N=3).Moreover,this modified electrode also showed good selectivity,reproducibility and stability.Thus,this method could be applied to determine H₂O₂ in some actual samples with satisfactory results.(4)In this chapter,nitrogen doped porous carbon(NPC)derived from ZIF-8 was firstly prepared following the previous chapter.Subsequently,copper and cobalt were decorated on NPC to form novel nanocomposite by hydrothermal reduction method.The Cu/Co@NPC composite material was characterized using X-ray powder diffraction,transmission electron microscopy and X-ray photoelectron spectroscopy.The electrochemical response of Cu/Co@NPC modified glassy carbon electrode towards hydrazine oxidation was investigated by cyclic voltammetry,demonstrating superior electrocatalytic activity compared with single material modified electrode.The oxidation peak current is the largest and the oxidation peak potential is the lowest.This may be attributed to synergistic effect based on fast electron transfer of Cu/Co with high surface area,strong conductivity of nitrogen doped porous carbon substrate.Under the optimum conditions,a linear range was obtained from 5 to 1850?mol/L with a limit of detection of 0.08?mol/L for hydrazine.In addition,good stability,excellent reproducibility and selectivity were obtained.At the end,the proposed sensor was successfully used to measuring the content of hydrazine in water samples with satisfied results.(5)In this chapter,carbon nanotubes wrapping nitrogen doped porous carbon was successfully prepared by in-situ growth at room temperature and high temperature carbonization method.The composite materials were characterized and then the electrochemical oxidation behavior of ascorbic acid,dopamine and uric acid at NPC@CNTs composites modified glassy carbon electrode was investigated by cyclic voltammetry.The results showed comparing with NPC-GCE,CNTs-GCE and bare GCE exhibited an excellent electrocatalytic activity towards AA,DA and UA with obvious current response and higher potential difference own to excellent conductivity of effecting combination between NPC and CNTs.Under the optimized conditions,the electrochemical measurement results showed a wide linear range of 40?2100?M(AA),0.5?49?M(DA)and 3?50?M(AA)with three detection limit of 0.36?M(AA),0.02?mol/L(DA)and 0.57?M(UA),(S/N=3).Moreover,the modified electrode showed good stability reproducibility and selectivity.The proposed method can be applied to determine AA,DA and UA simultaneously in actual samples.