Preparation Of Nano-Pd And Its Electrochemical Behaviour For Formaldehyde

The series nano-Pd materials were prepared via ultrasonic irradiation, visible lighting, simple heating and lyotropic liquid crystal (LLC) methods, respectively. The micro-morphology was controlled by change of experimental conditions. The electrocatalytic properties of the series nano-Pd materials modified glassy carbon electrode(Pd/GCE) for formaldehyde oxidation were investigated by cyclic voltammetry(CV) using three electrode system. The thesis was not only to obtain some kinds of simple synthetic methods for preparing nano-Pd materials with controllable morphology and size, but to supply theoretical basis for development of formaldehyde on the electrochemistry.1. The nano-Pd materials were prepared via ultrasonic irradiation, visible lighting, and simple heating methods separately in the palladium (Ⅱ) chloride H2O/EtOH solution without template and with the soft template of hexadecyl trimethyl ammonium bromide(CTAB) and the mixture of CTAB and sodium dodecyl sulfonate(SDS), respectively. The samples were characterized by XRD、TEM、UV、HRTEM and low temperature nitrogen adsorption-desorption. The effects of the experimental conditions on the micro-morphology of palladium nanoparticles were investigated and the reaction mechanisms were also discussed. The electrocatalytic properties of the nano-Pd modified glassy carbon electrode (Pd/GCE) for formaldehyde oxidation had been also studied systematically by cyclic voltammetry. Comparison of the electrocatalytic activity for formaldehyde and the relative standard deviation using three methods under the same experiment conditions, the results indicate that the nano-Pd materials wich were prepared via simple heating methods with the soft template of the mixture with a distributed size of (30±2) nm, has the best excellent electrocatalytic activity for the oxidation of formaldehyde with the peak I value of1345μA and the RSD (relative standard deviation) of0.72%. The optimized experimental condition was that the molar ratio of CTAB:SDS was100:1and the reaction time was3h. Under the optimized condition, the nano particles were easy to form regular morphology, such as quadrilateral nanoparticles.2. The phase diagrams of the ternary system of brine/SDS/cyclohexane/n-pentanol were determined at25℃. The small angle X-ray diffraction, DSC and the polarizing microscope were used for determining the structures of various samples in brinc/SDS/cyclohexane/n-pentanol liguid crystalline regions. The nano-Pd materials were prepared via without light, visible lighting and ultraviolet light methods respectively with lyotropic liquid crystal as soft template. The effects of the experimental conditions on the micro-morphology of palladium nanoparticles were investigated as well. The electrocatalytic properties of the nano-Pd modified glassy carbon electrode (Pd/GCE) for formaldehyde oxidation had been also studied systematically by cyclic voltammctry. Comparison of the electrocatalytic activity for formaldehyde and the RSD under the three experiment conditions, the results indicate that the nano-Pd materials wich were prepared via visible lighting methods with a distributed size of (31±2) nm. has the best excellent elcctrocatalytic activity for the oxidation of formaldehyde with the peak I value of988μA and the RSD of3.89%. The optimized experimental condition is that the strength of incandescent lamp was100W and the reaction time was6h. Under the optimized condition, the nano-particles were rhombus, pentagonal and regular quadrilateral. The size and morphology of the nano-Pd were similar to synthesis in24h without lighting and6h lighted. The results showed that the growth of the nano-Pd accelerated because of the function of light and heat.3. Comparison of the electrocatalytic activity for formaldehyde under the optimized experiment conditions, the results indicate that the glassy carbon electrode(Pd/GCF) was modified by nano-Pd materials which were prepared via simple heating methods, had the better electrocatalytic activity for the oxidation of formaldchyde.