Preparation Of Layered Double Hydroxide Nanocomposites And Its Application On Electrochemical Detection Of Hydrazine And Hydrogen Peroxide

A series of LDHs （immingled by Co, Ni, Fe） were synthesized by constant pH value co-precipitation method at room temperature, we study the electrochemistry properties ofhydrotalcite-like compounds at modified electrode. Then we prepare layered doublehydroxide （LDH） supported palladium nanomaterials and layered double hydroxide supportedPrussian blue nanocomposites via ion exchange process and chemical method. Thesynthesized sample was characterized by X-ray diffraction （XRD）, Transmission electronmicroscope （TEM） and X-Ray photoelectron spectroscopy （XPS）. The nanomaterials wereimmobilized on glassy carbon electrode for electrochemical oxidation of hydrazine andelectrochemical detection of hydrogen peroxide （H2O2） respectively. The research contentsare as follows:1. LDHs was prepared from Mg（NO₃）₂·6H₂O and Al(（NO₃）₃·9H₂O by constant pH value co-precipitation method at room temperature. Conducting PANI was obtained by miniemulsioncopolymerization, using DBS as the doping agent and surfactant and ammonium persulfate asthe oxidant. Chemical oxidative polymerization of aniline was performed in a micellarsolution of dodecyl benzenesulfonate （DBS, anionic surfactant） to obtain conductive particles.The electrochemical behavior of PANI and its complexes with different LDHs atmodifiedglass carbon electrode was investigated by cyclic voltammetry （CV）. Fe（CN）₆^3-has thehighest reduction current and oxidation current at the modified glass carbon electrode (LDHsof n(Mg²⁺)/n(Al³⁺)=3), the result shows that the plate charge density impacts the capabilityof the electron transfer of this modified glass carbon electrode. Fe（CN）₆^3-has lower reductioncurrent and oxidation current at the modified glass carbon electrode （LDHs immingled by Co,Ni, Fe）, the result shows that the structure of hydrotalcite-like compounds impacts theelectrochemistry properties of this modified glass carbon electrode.2. PdCl₄^2-was successfully intercalated in the gallery space of Mg-Al layered doublehydroxide （LDH） via ion exchange process, and reduced by hydrazine to prepare layereddouble hydroxide （LDH） supported palladium nanomaterials. The synthesized sample wascharacterized by X-ray diffraction （XRD）, Transmission electron microscope （TEM） and X-Ray photoelectron spectroscopy （XPS）. The nanomaterial was immobilized on glassy carbonelectrode for electrochemical oxidation of hydrazine in phosphate buffer （pH7.0） using cyclicvoltammetry （CV）. The electrochemically effective surface areas were determined bychronocoulometry （CC）. Amperometric response was studied at the working potential-0.1Vand found that the anodic peaks current of modified electrodes having a good linear relationship to hydrazine concentration in the range of1.0×10^-5～2.0×10^-4mol·L^-1. Theelectrochemically effective surface areas for GCE and LDH-Pd⁰/GCE were0.02089cm²and0.02762cm²respectively. The oxidation of hydrazine on modified electrode was diffusioncontrolled process, with4electrons and4protons taking part in.3. Layered double hydroxide supported Prussian blue nanocomposites （denoted as LDH-PB）were successfully prepared via chemical method and characterized by Fourier transform IR,X-ray diffraction, Transmission electron microscope （TEM）, chronocoulometry and cyclicvoltammetry. With the help of polyaniline, polystyrene sulfonate and LDH-PB compositefilm could be immobilized on glassy carbon electrode for electrochemical detection ofhydrogen peroxide （H2O2）. The fabricated electrode exhibits a well-defined pair of redoxpeaks and excellent electrocatalytic activity. This sensor response to H2O2shows a linearrange of6×10^-6～1.86×10^-4mol·L^-1with the low detection limit of0.38μmol·L^-1at a signal-to-noise ratio of3. For the advantages of easy update, low cost and good stability, this sensorcan be expected to wide use in the pharmaceutics, clinical diagnostics, and industrialdetection of hydrogen peroxide.