| Nanomaterials Nano-sized metal material based on its own special physical and chemical properties,and shows superior performance in the study of electrochemical sensors,make it become one of hot topics in the study of electrochemical sensor.There were seven kinds of nanocomposite were preparated which were used to fabricate glucose sensor and H2O2 sensor Investigation on the relationgship between response behavior of the sensors and morphology and structure of sensing interface material was carried out.Thus,the new methods to detect glucose,H2O2 and methanol established.The research for the development of higher sensitivity,higher selectivity and lower detection limit of electrochemical sensors provide some new ideas.to expand the application range of nanomaterials.There are six chapters in the dissertation,and the main contributions of the author are presented as follow:1.An efficient and rapid method was developed for the preparation of halloysite nanotubes(HNTs)loaded with Pd nanoparticles(PdNPs)to make a non-enzymatic sensor for glucose.In the preparation step,HNTs self-assembled by sodium dodecylsulfate(SDS)provides an ideal template for loading and arrangement of PdNPs on HNTs.The obtained PdNPs-HNTs nanocomposite material was placed on a glassy carbon electrode to detect glucose.The morphology and composition of the PdNPs-HNTs was investigated by using X-ray powder diffraction(XRD),transmission electron microscopy(TEM)and energy-dispersive X-ray spectrum(EDX).Electrochemical impedance spectroscopy(EIS)reveals charge transfer resistance for the modified electrode.Cyclic voltamnetry and amperometry were used to measure the electrocatalytic activity of the PdNP-HNT-modified electrode for non-enzymatic oxidation of glucose.The current response of the PdNP-HiNT-modified electrode towards glucose covers two linear regions(0.5 ?M to 2.0 mM and 2.0 mM to 15.0 mM).The detection limit is 0.43 ?M.Compared with other glucose sensor based on Au,the PdNPs-HNTs/GCE shows one orders of magnitude wider linear range.The poly(diallyldimethylammonium chloride)(PDDA)was used as a modifier agent which formed a functionalized layer on Halloysite nanotubes(HNTs)which are natural and abundant nanomaterial supported platinum nanoparticles(PtNPs)was prepared for the Electrocatalysis towards methanol.The oxidation of methanol was investigated in acidic media via cyclic voltanmetric analysis in the mixed 1.0 M methanol and 0.5 M H2SO4 solutions.PtNPs-PDDA-HNTs have higher electrocatalytic activity,more negative onset potential.It also has larger electrochemical active surface area(ECSA)which was shown to158.4 m2/gPt indicated higher hydrogen adsorption amount than 139.2 m2/gPt of the pristine PtNPs-HNTs.Furtermore,the PtNPs-PDDA-HNTs catalyst has a long-time stability and reproducibility for oxidation of methanol,suggesting that it is a great potential for applications in direct methanol fuel cells.2.Pd was loaded onto polystyrene microsphere.Based on the PdNPs-Ni(OH)2-PS,a glucose sensor was fabricated.Investigation on the relationgship between response behavior of the sensor and morphology and structure of sensing interface material was carried out.Thus,the new method to detect glucose was established.The PdNPs-Ni(OH)2-PS was characterized by TEM and XRD.The sensor exhibits excellent electrochemical performance toward glucose oxidation and a linear range from 2.0 ?M to 13.0 mM,a limit of 1.0 ?M(S/N = 3)and a high sensitivity of 172.5 ?AmM-1cm-2.Compared with other glucose sensor based on Pa,the PdNPs-Ni(OH)2-PS/GCE shows a low oxidation potential closed to zero.3?Carbon quantum dots(C-dot)was synthesized by hydrothermal which were uniform particle size distribution.Carbon quantum dots were doped into NiCo2O4 and AgNPs@PdNP.Based on the nanoparticles,non-enzymatic glucose sensor and H2O2 sensor were fabricated.Investigation on the relationgship between response behavior of the sensor and morphology and structure of sensing interface material was carried out.Thus,the new methods to detect glucose and H2O2 were established.The NiCo2O4@C-dot/GCE exhibits excellent electrochemical performance toward glucose oxidation and a linear range from 1 ?M?17 mM,a limit of 0.3 ?M(S/N = 3)and a high sensitivity of 402.93 ?A mM-1 cm-2.Compared with other glucose sensor,the NiCo2O4@C-dot/GCE shows low detection limit and high sensitivity.The sensor of AgNPs@PdNPs@C-dot/GCE exhibits excellent electrochemical performance toward H2O2 with a linear range from 1.0×10-7 M to7.5×10-3 M,,a limit of 3.5×10-8 M(S/N = 3)and a high sensitivity of 117.04 ?AmM-1cm-2.Compared with other H2O2 sensor,the AgNPs@PdNPs@C-dot/GCE shows low detection limit and high sensitivity.4.A sandwich structured nanocomposite consisting of reduced graphene oxide modified with silver and gold nanoparticles supported on Co3O4 was synthesized and used for fabricating a nonenzymatic sensor for H2O2 and glucose.The morphology and composition of the nanocomposite was characterized by transmission electron microscopy,scanning electron microscopy,X-ray powder diffraction and FTIR.The composite was placed on a glassy carbon electrode which then displayed excellent performance in terms of electroreduction of H2O2 and glucose.The AgNPs-Co3O4-rmGO/GCE for H2O2 sensor,if operated at pH 7.4 at a working potential of 0.4 V(vs.SCE)has the following features:(a)linearity in the 0.1 ?M to 7.5 mM concentration range;(b)a sensitivity of 146.5 ?A·mM-1·cm-2;(c)a 35 nM detection limit at a signal-to-noise ratio of 3,Compared with other H2O2 sensor based on Ag,the AgNPs-Co3O4-rmGO/GCE shows one orders of magnitude wider linear range.The glucose sensor of AuNPs-Co3O4-rmGO/GCE for glucose is long-term stable,well reproducible and selective.AuNPs-Co3O4-rmGO/GCE has the following features:(a)linearity in the 0.1 ?M?15.0 mM concentration range;(b)a sensitivity of 282.08?A·mM-1·cm-2;(c)a 0.03 ?M detection limit at a signal-to-noise ratio of 3.Compared with other glucose sensor based on Au,the AuNPs-Co3O4-rmGO/GCE shows almost two times sensitivity and two orders of magnitude wider linear range. |
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