Self-assembly Films Based On Carbon Nanotubes,Graphene And Its Electrochemical Sensing

Nanomaterials with unique low-dimensional structures,fantastic physical and chemical properties have been extensively used in the new energy,the environment,biology,medicine,information and electrochemical transducer.In this thesis,carbon and noble metal nanomaterials modified glassy carbon electrodes had been fabricated by layer by layer assembly technology.These sensors were applied in the determination of paracetamol,dopamine,phenols and hydrogen peroxide,respectively,with excellent performance.A new carboxylic acid functionalized multi-wall carbon nanotubes(CMWNTs)thin film was layer by layer(LBL)assembled via covalent bond by using ethylenediamine as an arm linker,and applied to the determination of paracetamol,dopamine and phenols,respectively.Scanning electron microscopy(SEM)and Fourier transform infrared(FT-IR)spectroscopy were used to characterize the assembly process.(1)Electrochemical studies indicated that the modified electrode possess a remarkably electrocatalytic activity towards paracetamol at a lower potential compared with the bare glassy carbon electrode(GCE).The thickness of the film assembled CMW-NTs are easily controlled by changing the numbers of the cycles in the LBL assembly process,which also effectively tuned the electrocatalytic activity of the film towards paracetamol.The experiments results display that the six layers film performs the best electrocatalytic activity to paracetamol.The constructed electrode with six layers showed a good sensitivity in the linear range of 1-200 ?M,and a detection limit of 0.092 ?M(S/N=3).Furthermore,the CMWNTs film also showed good selectivity and excellent stability for the determination of paracetamol.(2)The constructed electrode showed a good sensitivity to dopamine in the linear range of 6-370?M in pH 7.0 PBS,and a detection limit of 0.532 ?M(S/N=3).Furthermore,the CMWNTs film also showed good selectivity and excellent stability for the determination of dopamine.(3)The electrochemical experiments indicated that the modified electrode could simultaneously determine the hydroquinone(HQ)and catechol(CC).Differential pulse voltammetry(DPV)experiments exhibited the oxidation peak current of HQ was linear to its concentration in the range of 10-120 ?M with the detection limit of 2.3?M in the present of 0.1 mM CC,and at the same time the oxidation peak current of CC was linear to its concentration in the range of 5-80 ?M with the detection limit of 1 ?M in the present of 0.1 mM HQ.Moreover,the CMWNTs modified electrode also showed excellent selectivity and stability.The carboxyl functionalized graphene was covalent monolayer assembled to the surface of glassy carbon electrode for simultaneously determination of HQ and CC.The proposed sensor performed excellent electrochemical responses for HQ and CC at lower potential.Under the optimized condition,the detection limits of HQ and CC are 0.2 and 0.6 ?M(S/N = 3)with linear ranges of 1-210 ?M and 5-250?M in the presence of 50 ?M isomer,respectively.And the facile preparation of this sensor has a good stability and reproducibility.The Pt nanoparticles and graphene non-enzyme hydrogen peroxide sensor was prepared by electro deposition Pt onto the carboxyl functionalized graphene monolayer assembled film.The sensor could significantly decrease the overpotential of hydrogen peroxide owing to the synergistic effect of the excellent properties of Pt nanoparticles and graphene,so it can determine H2O2 at the adjacent potential of zero(-0.01V)and avoid interference from other co-existing substances.