Study On Bioelectrochemical Sensing And Design Of Transition Metal And Transition Metal Oxides Nanocomposites

Transition metal and transition metal oxides are very important catalyst in many areas due to the advantages of poisoning resistance,good stability,repeatability and high selectivity.Among them,the nickel-based nanomaterials were considered as more preferable material owing to the low cost and abundance on the earth,carbon materials with large specific surface area,good conductivity,high stability and good biological compatibility,are always used as substate to composite active catalyst.However,it is still a great challenge to load the nickel-based eatalysts on carbon materials in an easy process.Therefore,in present work we provide the design and prepare the nickel-based materials/carbon composite electrochemical catalysts in order to avoid the problems of the tedious synthetic process and uneasily control morphology.Four different nickel based catalysts/carbon materials composite electrochemical catalysts were systemly studied and the non-enzymatic glucose sensing performance were investigated in the research.The results are listed as followings:1.The preparation of amorphous Ni(OH)2/CQDs microspheres and its non-enzymatic glucose sensing properties.The amorphous Ni(OH)2/CQDs microspheres were prepared by a CQDs assistant crystallization inhibition process.The morphologies and composition of the microspheres were characterized by SEM,TEM,XRD,EDS,and TG/DSC.The results showed that the microspheres had uniform heterogeneous phases with amorphous Ni(OH)2 and CQDs.The sensor based on amorphous Ni(OH)2/CQDs microspheres showed remarkable electrocatalytic activity towards glueose oxidation comparing to the conventional crystalline Ni(OH)2,which included two linear range(20 ?M-350 ?M and 0.45 mM-2.5 mM)with high selectivity of 2760.05 ?A.mM-1·cm-2 and 1853.64 ?A.mM-1.cm-2.Moreover,the interference from the commonly interfering species such as urea,ascorbic acid,NaCl,L-proline and L-Valine,can be effectively avoided.The high sensitivity,wide glucose detection range and good selectivity of the electrode may be due to their synergistic effect of amorphous phase and CQDs incorporation.2.The synthesis of NiO/Nitrogen doped carbon sphere(NiO/NCS)composites and the nonenzymatic glucose sensing performance.The NiO/NCS were successfully achieved via an easy one pot synthetic method with urea acting as both nitrogen source and Ni precipitator.The electrocatalytic performances of the obtained NiO/NCS modified glass carbon electrodes showed superior activity for direct electrocatalytic oxidation of glucose than that of nitrogen free NiO/carbon sphere(NiO/CS),which might be due to the synergistic effect of the properties of NCS and NiO nanoparticles.The introduce of nitrogen can improve the conductivity of the NiO/NCS and accordingly accelerate the electron transport within the composites,which was very beneficial to improve the sensitivity to glucose detection for NiO/NCS modified electrodes.The NiO/NCS electrodes exhibited two corresponding linear regions of 1-800 ?M and 4-9 mM with the sensitivity of 398.57 ?A·mM-1·cm-2 and 17.81 ?A·mM-1·cm-2,and the detection limit of 0.25 ?M and 0.05 mM respectively.Moreover,the NiO/NCS composites have also exhibited good selectivity.3.The carbon nanotubes entangled Ni/NiO porous polyhedrons and its nonenzymatic glucose sensing performance.The CNTs/Ni/NiO were obtained by in situ growing process with Ni-MOF precursor acting as both the carbon source and catalyst(Ni/NiO)source,which showed highly improved electrochemical performance.The enhanced glucose oxidation activity of Ni/NiO/CNTs may be due to die synergistic effect of metallic nickel and carbon nanotubes.4.The design of hierarchical CuCO2O4/C microspheres and the nonenzytamci glucose sensing investigation.The hierarchical CuCO2O4/C microspheres were fabricated via a two-step method involving hydrothermal and calcination processes.SEM,TEM,HRTEM,XRD and XPS were used to characterize the morphology,structure,and composition of the materials.The CuCO2O4/C microspheres have a hierarchically flower-like structure composed of nanoparticles-stacked nanosheets.Moreover,the as-prepared double-metal oxide hierarchical microsphere composites exhibit greatly improved electrochemical performance than that of pure CuCO2O4,owing to the synergistic effect of CuCO2O4 and carbon spheres.The CuCO2O4/C5:1 modified electrode exhibited high sensitivity of 707.71 ?A-mM-1·cm-2 in a wide linear range from 5 to 8000 ?M with detection limit of about 1.5 ?M.The outstanding glucose sensing performance of CuCO2O4/C5:1 demonstrated that this kind of spinel bimetallic oxides composites can be favorable candidates for the development of non-enzymatic sensor.