Studies On The Synthesis Of Nanomaterials And Their Applications In Electrochemical Catalysis And Chemical Oxgen Demand Determination

This dissertation studies the preparation of the platinum and titanium dioxide nanomaterials by electrochemical method as well as the application in electrocatalysis and photoelectrocatalysis. As to the synthesis of platinum nanomaterials, the gas bubble dynamic template method was firstly adopted to synthesize different morphology of platinum nanomaterials by adjusting the concentration of CuSO4. In addition, highly ordered anatase TiO₂ nanotube arrays were prepared by potentiostatic anodization of Ti foil under high potential followed by annealing at high temperature. What's more, Au nanoparticles were electrodeposited at the highly ordered anatase TiO₂ nanotube array (TiO₂NA) electrode under sonicating to prepare Au nanoparticle modified TiO₂NA electrode. All the nanomaterials were characterized by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and other technologies. The application of platinum nanomaterials in electrocatalysis was investigated. The pure TiO₂NA and Au nanoparticle modified TiO₂NA electrodes were applied in photoelectrochemical experiments for the determination of chemical oxygen demand (COD) , respectively. Specific tasks are as follows:Different morphologies of platinum have been facilely produced via an electrochemical deposition copper accompanying suitable amount of hydrogen evolution followed by a replacement reaction between the copper sacrificial template and H2 PtCl6 in solution. The resultant Pt has the similar morphology with initial Cu. Compared with commercial Pt/C, these platinum nanomaterials show excellent catalytic activity toward oxygen reduction and methanol oxidation.Highly ordered TiO₂ nanotube array was prepared by a potentiostatic anodization in the electrolyte of low concentration of hydrogen fluoride. High temperature annealing to form a better photoelectrocatalytic active anatase titanium dioxide nanotube array electrode, the pure TiO₂ NA and Au nanoparticle modified TiO₂NA electrodes were used to determine COD of real samples, respectively. Performances of as-prepared sensors were compared, and stability, reproducibility and lifetime for long-term determination COD were investigated. The sensors are used for the development of online monitoring instrument for determination of COD. Long-term test results indicate that the preparation process is simple and cheap, the electrodes have high surface area, long lifetime, and high photoelectrocatalytic activity. The time for photoelectrocatalytic determination COD is short (only 2-4 minutes). The method proposed is simple, fast, cost effective, and environmental friendly. Au nanoparticle modified TiO₂NA sensor has lower photoelectro-resistance, higher photoelectrocatalytical activity and stability than that of pure TiO₂NA sensor under the same conditions. Therefore, such nanotube array sensors are expected to be widely applied in the development of environmental monitors.