Fabrication And Application Of Electrochemical Sensors Based On Low-dimensional Functionalized Nanocarbon Materials And Its Composites

During the past few years,graphene and graphene-like nanomaterials,have become the hotspots in materials science and analytical chemistry.Graphene and graphene-like materials have various attractive physical and chemical properties,such as unique structures,ultra-large surface area,abundant active site and perfect mechiancal performance.Besides their utilization during the development of energy storage and catalysis,they are also widely used in the electrochemical sensing area for the modification of electrodes.The functionalization of graphene and graphene-like nanomaterials can efficiently combine the excellent properties of each component,and further activate the synergic effects between them,as a result,the sensing performance of the proposed electrochemical sensors can be highly improved.In this work,we synthesized several functionalized graphene and graphene-like nanocomposites.The materials were prepared mainly through electrochemical methods,along with diferent soft chemistry methods.Then further applied as electrochemical sensing platforms for the detection of various analytes,such as environmental pollutants,biological molecules,medical molecules,and explosives.The main idea of this work is to improving the sensing performance of the materials through doping and functionalization,and the contents can be divided into the following six parts:(1)A high-performance electrochemical sensor based on g-C3N4-PEDOT for the determination of acetaminophenA fast,ultrasensitive electrochemical sensing platform based on graphitic carbon nitride-electrochemically deposited-poly(3,4-ethylenedioxythiophene)(g-C3N4-PEDOT)composite was constructed by in-situ electropolymerization and applied for the quantitative determination of acetaminophen(AP).PEDOT was introduced as the conducting matrix for developing g-C3N4 composite to complement the poor conductivity disadvantage of g-C3N4.The strong affinity and synergetic effect between g-C3N4and PEDOT,which were analyzed by PM6 computational calculation,highly improved the electron transfer property and remarkably enhanced the electrochemical catalytic activity of the composite.The g-C3N4-PEDOT modified glassy carbon electrode(GCE)demonstrated better electrocatalytic activity towards the oxidation of AP than bare,g-C3N4and PEDOT modified ones.Under the optimized conditions,the oxidation peak currents at the g-C3N4-PEDOT/GCE increased linearly in the concentration range of AP from 0.01 to 2 μM and 2 to 100μM,and an ultra-low limit of detection(LOD)of 31.97 nM was obtained(S/N=3).In addition,the g-C3N4-PEDOT/GCE was successfully applied for the AP determination in the clinical human serum,and also exhibited excellent selectivity,reproducibility and stability.Except the novel AP determination approach,moreover,this work provided a new electrochemical application angle of graphitic carbon nitride theoretically as well as experimentally.(2)Boron-doped graphene for fast electrochemical detection of HMX explosiveHerein,we proposed a novel boron-doped graphene(B-GE)modified glassy carbon electrode applied as a simple,sensitive electrochemical high melting explosive(HMX)sensor.The morphology and structure features of B-GE were characterized.The electrochemical behaviors of HMX on the B-GE modified GCE were investigated by cyclic voltammetry(CV).Under the optimized conditions,CV was used for the quantitative detection of HMX,and the reduction peak cu.rrent exhibited good linear dependence with the concentration of HMX in the ranges of 2-20 μM and 20-100 μM.The low detection limit was calculated as 0.83 μM(245.81 ppb).Furthermore,the B-GE/GCE showed satisfactory repeatability,high selectivity and stability.The reduction reaction mechanism of HMX on B-GE modified electrode was explored by computational theoretical analysis.Additionally,the differences of the reduction mechanisms from nitroaromatic explosives were discussed.(3)Bamboo fungus-derived porous nitrogen-doped carbon material for the fast,sensitive determination of Bisphenol ABiomass-derived carbon materials have been considered as perfect substitutes for the traditional doped carbon materials,owing to its simple synthesis,rich-doped hetero-atoms,low cost and satisfactory electrochemical properties.In this paper,a rich nitrogen-doped carbon(NDC)material derived from bamboo fungus by simple carbonization was firstly applied for the electrochemical determination of Bisphenol A(BPA).NDC showed high catalytic activity towards the BPA oxidation for its rich doped nitrogen,high conductivity and porous structure.The morphology and structure features of NDC were characterized by the transmission electron microscopes and Raman spectrum.Meanwhile,the electrochemical properties of NDC modified glassy carbon electrode and the behaviors of BPA on the NDC modified GCE(NDC/GCE)were estimated by cyclic voltammetry and electrochemical impedance spectroscopy(EIS).Under the optimum conditions,differential pulse voltammetry(DPV)was used for the quantitative determination of BPA.A low detection limit of 1.07μM was obtained within the range of 1.0μM to 50.0μM.And the NDC/GCE was further applied for the practical determination of BPA in soil extract samples successfully.The results revealed that the low-cost,simple and sensitive NDC based platform could be a potential approach for the practical detection of BPA.(4)UA sensor based on a glassy carbon electrode modified with nitrogen-doped graphene/PEDOT composite and copper-nickel alloy nanoparticlesCu-Ni alloy nanoparticles was deposited onto PEDOT/nitrogen-doped graphene(NGE),and further applied for the selective determination of uric acid(UA).The obtained Cu-Ni alloy nanoparticles were well-dispersed with alloy features and highly improved electrochemical performance together with PEDOT and NGE in the detection of UA.The morphology and structure of Cu-Ni alloy nanoparticles decorated PEDOT/NGE were studied by transmission electron microscopes,Raman spectrum and The ratio of Cu2+ and Ni2+,the reduction potential and time and the modified amount of PEDOT and NGE were optimized accordingly.Under the optimized condition,the response current of the sensor is linear to UA concentration within the range of 1-10μM and 10-50μM.A low detection limit of 0.24μM was obtained.(5)BPA sensor based on a glassy carbon electrode modified with electrochemically reduced graphene oxide/copper-gold alloy nanoparticlesCu-Au alloy nanoparticles-electrochemically reduced graphene oxide(ERGO)composite was developed through a facile and green one-step electrochemical reduction process from GO and metal precursors.Cu-Au alloy nanoparticles were well dispersed with high density on ERGO.The Cu-Au/ERGO modified electrode exhibits large surface area,high conductivity and electrocatalytic activity,which make it a perfect candidate for the detection of BPA.The modification amount of Cu-Au alloy nanoparticles and ERGO,as well as the reduction potential and time were optimized,in order to obtain the best sensing performance.The Cu-Au/ERGO nanocomposite based nonenzymatic sensor presents high selectivity,rapid response and satisfied reproducibility and stability.A low detection limit of 0.59μM was obtained within the linear range of 0.1-1 and 1-50μM.(6)Electrochemical Detection of Dopamine by a Calixarene-Cellulose Acetate Mixed Langmuir-Blodgett MonolayerA fast,highly-sensitive electrochemical sensing platform based on cellulose acetate-calix[6]arene mixed Langmuir layer,was transferred onto a preoxidized gold electrode and applied for the quantitative determination of dopamine.Cellulose acetate was introduced as a means of better organizing the calix[6]arene monolayer and therefore improved the electrochemical sensing performance.The modified gold electrode demonstrated better recognition and sensing ability towards dopamine as compared with electrodes modified by a single component.Under the optimized conditions,the reduction peak currents at the cellulose acetate-calix[6]arene mixed monolayer modified electrode increased linearly within the concentration range of dopamine from 5-100 and 100 7500 nM,and exhibited a very low limit of detection of 2.54 nM(S/N=3).These results suggest a superior approach for controlling the electrode-electrolyte interface and optimize its electroanalytical performance.