Synthesis,Surface Modification And Electrochemical Performance Of Bismuth-based Composite Oxide Nanorods

Great research interest has been devoted to bismuthate nanomaterials owing their unique electrochemical,optical and catalytic properties.The current research status and progress of the synthesis of bismuth-based one-dimensional?1D?nanoscale materials and electrochemical detection of biomolecules are discussed in this dissertation.Zinc bismuthate nanorods and bismuth nickelate nanorods have been synthesized by simple hydrothermal process without surfactants,and the polyaniline nanocomposites were synthesized by using an in situ polymerizing process.The structure,morphology and size of product were analyzed by using X-ray diffraction?XRD?,scanning electron microscope?SEM?,transmission electron microscope?TEM?,high-resolution TEM?HRTEM?.Some influential factors of the products were studied systematically and the formation mechanism is proposed.The electrochemical behaviors of L-cysteine?L-CySH?at the zinc bismuthate nanorods and polyaniline/zinc bismuthate nanorods composite modified glassy carbon electrodes?GCEs?,electrochemical responses of tartaric acid at the bismuth nickelate nanorods and polyaniline/bismuth nickelate nanorods composite modified GCEs were investigated in detail.It is of important research significance for the surface modification,controlled synthesis and application of bismuth-based composite oxide 1D nanoscale materials.Zinc bismuthate nanorods with single crystalline cubic ZnBi₃₈O₅₈ phase have been synthesized by a simple hydrothermal process using sodium bismuthate and zinc acetate without any additives.Electron microscopy images show the nanorods have the length and diameter of 2-10?m and 40-250 nm,respectively.The growth of the zinc bismuthate nanorods has been proposed as a nucleation and crystalline growth process based on the structure and morphology of the products obtained from different hydrothermal conditions.Zinc bismuthate nanorods modified GCE has been prepared and used for the electrochemical determination of L-cysteine.A pair of semi-reversible redox peaks located at-0.07 V and-0.52 V are observed at the nanorods modified GCE in KCl solution and the electrode process is diffusion controlled.As the concentration of l-cysteine increases and the scan rate increases,the intensity of the CV peak increases significantly.There is a linear relationship between the peak current and concentration of0.0001-2 mM.The detection limit is 0.074?M?based on the signal-to-noise ratio of 3?with a correlation coefficient of 0.996.The nanorods modified GCE shows good stability and reproducibility.Single crystalline bismuth nickelate nanorods with cubic Bi₁₂NiO₁₉ phase have been successfully synthesized by a facile hydrothermal using bismuth acetate and sodium bismuthate without any additives.Electron microscopy show that the diameter and length of the bismuth nickelate nanorods are 30-100 nm and 1-3?m.The formation,length and diameter of the nanorods depend on the hydrothermal temperature and duration time.The bismuth nickelate nanorods are applied as the GCE materials for the detection of tartaric acid in KCl solution.The roles of scan rate,electrolyte species and tartaric acid concentration on the electrochemical responses of tartaric acid have been investigated.The obtained linear concentration calibration plot shows a low detection limit of 0.52?m,wide linear range of 0.001-2 mM and correlation coefficient of 0.996.The bismuth nickelate nanorods modified GCE shows good reproducibility and stability.A simple in-situ polymerizing aniline monomer process in aqueous solution has been used for the synthesis of the polyaniline/zinc bismuthate nanorods composites and polyaniline/bismuth nickelate nanorod composites.XRD pattern shows that the nanocomposites have cubic ZnBi₃₈O₅₈ crystallization structure and cubic Bi₁₂NiO₁₉ phase.TEM and HRTEM techniques show that the amorphous polyaniline attaches firmly to the surface of the nanorods.The polyaniline/zinc bismuthate nanocomposites modified GCE exhibits good electrocatalytic activity toward L-Cysteine.The influences of scan rate,L-Cysteine concentration and polyaniline content are investigated.With increasing the polyaniline content from 10wt.%to 40wt.%,the LOD decreases obviously from 0.032?M to 0.012?M.The polyaniline/zinc bismuthate nanocomposites modified GCE shows good reproducibility and stability.The GCE is modified with polyaniline/bismuth nickelate nanorod composites for the electrochemical detection of tartaric acid.Electrochemical responses of tartaric acid have been investigated by controlling the parameters,such as scan rate and tartaric acid concentration.The peak current is linearly increased with increasing the scan rate and tartaric acid concentration.The linear range increases from 0.001-2 mM to 0.0005-2 mM and LOD decreases from 0.37?M to 0.18?M as increasing the polyaniline mass percentage from 10wt.%to 40wt.%.Compared with the bare GCE and nanorods modified GCE,polyaniline/nanorod nanocomposites greatly enhances the electrochemical detection performance of L-cysteine and tartaric acid.