Synthesis,Surface Modification And Electrochemical Performance Of Bismuthate Nanoscale Materials

Bismuthate nanscale materials exhibit extensive application potential in the field of electrochemical sensor owing to good electrochemical performance.The research status and progress of the synthesis,electrochemical detection of biological molecules of bismuthate nanoscale materials and polyaniline（PAn）combined nanoscale materials are reviewed.Cu bismuthate nanosheets and Ba bismuthate nanobelts were synthesized by a simple hydrothermal process,PAn/Cu bismuthate nanosheets and PAn/Ba bismuthate nanobelts were obtained by an in-situ polymerization route.The structure,morphology and size of the products were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,and high-resolution TEM（HRTEM）.The roles of the growth conditions on the formation of the Cu bismuthate nanosheets and Ba bismuthate nanobelts were systematically studied.The electrochemical detection performance of tartaric acid（TA）was systematically studied using Cu bismuthate nanosheets（Ba bismuthate nanobelts）and PAn/Cu bismuthate nanosheets（Ba bismuthate nanobelts）modified glassy carbon electrodes（GCEs）.It is of great significance to research the controllable synthesis,surface modification and electrochemical sensor application of bismuthate nanoscale materials.Cu bismuthate nanosheets were prepared by hydrothermal process using sodium bismuthate and copper iodide as the raw materials.XRD result shows that the Cu bismuthate nanosheets consist of polycrystalline tetragonal CuBi₂O₄ phase.SEM and transmission electron microscopy observations show that the nanosheets have a thickness of 50 nm and a width of 300 nm to 2μm.The products obtained from the hydrothermal conditions with low temperature（80℃and 120℃）and short duration time（0.5 h）are composed of layer-shaped morphology with tetragonal CuBi₂O₄,tetragonal Bi₂O₃ and monoclinic CuO phases.The intensity of the diffraction peaks of tetragonal CuBi₂O₄ phase increases obviously with the increase of the duration time and hydrothermal temperature.The formation and growth of the Cu bismuthate nanosheets can be explained by the nucleation and growth process.A pair of quasi-reversible electrochemical cyclic voltammetry（CV）peaks located at-0.45 V（cvp1）and-0.02 V（cvp1’）,respectively exist in the CV curve at the Cu bismuthate nanosheets modified glassy carbon electrode（GCE）in the mixed solution of 2 mM TA and 0.1 M KCl.The current of the CV peaks increases linearly with the increase of the scan rate and TA concentration.The linear detection range and detection limit are 0.005-2 mM and 1.6μM,respectively.Cu bismuthate nanosheets modified GCE shows good electro-catalytic activity for the electrochemical detection of TA.Ba bismuthate nanobelts have been prepared by a simple hydrothermal process using sodium bismuthate and barium acetate as the raw materials.XRD analysis shows that the Ba bismuthate nanobelts are composed of single crystalline monoclinic BaBiO_2.5.The nanobelts have flat tips,and the length,thickness and width are several dozens of micrometers,1μm and 50 nm,respectively.The products consist of nanosheets and fragments with irregular surface when the experiments were performed in the hydrothermal condtions of low hydrothermal temperature（80℃and 120℃）and short duration time（0.5 h）.The products are mainly composed of Ba bismuthate nanobelts with the duration time increasing to 12 h and 24 h,respectively at 180℃.The nanosheets and fragments are transformed to Ba bismuthate nanobelts with increasing the duration time and hydrothermal temperature.A pair of quasi-reversible electrochemical CV peaks located at-0.49 V and+0.01 V,respectively are observed from the CV curve at the Ba bismuthate nanobelts modified GCE in the mixed solution of 2 mM TA and 0.1 M KCl.The intensity of the electrochemical CV peak increases linearly with increasing the scan rate and TA concentration.The linear detection range and detection limit are 0.001-2 mM and 0.12μM,respectively using Ba bismuthate nanobelts modified GCE for the detection of TA.PAn/Cu bismuthate nanosheets（Ba bismuthate nanobelts）with different PAn content have been prepared by an aniline monomer in-situ polymerization route.XRD result shows that the PAn/Cu bismuthate nanosheets consist of tetragonal CuBi₂O₄ phase.PAn/Ba bismuthate nanobelts are composed of monoclinic BaBiO_2.5 phase.TEM and HRTEM observations show that amorphous PAn nanoscale particles with the size of less than 100nm attach to the surface of Cu bismuthate nanosheets（Ba bismuthate nanobelts）.The content of the amorphous PAn nanoscale particles in the combined Cu bismuthate nanosheets（Ba bismuthate nanobelts）with increasing the PAn content.A pair of quasi-reversible CV peaks located at-0.01 V（cvp1）and+0.04 V（cvp1′）,respectively exist in the CV curve at the 20wt.%PAn/Cu bismuthate nanosheets modified GCE in the mixed solution of 2 mM TA and 0.1 M KCl.The The current of the CV peak increases linearly with increasing the scan rate and TA concentration.Detection limit is0.58μM and linear detection range is 0.001-2 mM using 20wt.%PAn/Cu bismuthate nanosheets modified GCE.PAn enhances obviously the electrochemical activity for TA of Cu bismuthate nanosheets modified GCE.The linear detection range increases from0.005-2 mM to 0.001-2 mM and the detection limit decreases from 2.3μM to 0.43μM with increasing the PAn content from 10wt.%to 40wt.%.PAn/Cu bismuthate nanosheets modified GCE has good repeatability and stability.A pair of quasi-reversible CV peaks located at-0.69 V（cvp1）and+0.49 V（cvp1′）,respectively exist in the CV curve at the 20wt.%PAn/Ba bismuthate nanobelts modified GCE in the mixed solution of 2 mM TA and 0.1 M KCl.The 20wt.%PAn/Ba bismuthate nanobelts modified GCE exhibits good electro-catalytic activity toward TA with a wide linear detection range and detection limit of 0.0005-2 mM and 0.09μM,respectively.PAn enhances obviously the electrochemical activity toward TA of the Ba bismuthate nanobelts modified GCE.With the increase of scan rate and TA concentration,the CV peaks current increases linearly.The linear detection range increases from 0.001-2 mM to 0.0005-2 mM,and detection limit decreases from 0.12μM to 0.08μM with increasing the PAn content from 10wt.%to 40wt.%.The PAn/Ba bismuthate nanobelts modified GCE shows good stability and reproducibility for the detection of TA.