Electrochemical Preparation And Applications Of Metal Multi-class Structure Of Nanomaterials

Noble metal nanostructures have been the subject of much intensive research due to their novel properties and intriguing applications in different areas such as electronic, magnetic, catalysis, chemical and biological sensing, optical, micromechanical devices and surface-enhanced Raman scattering (SERS) detection biomedical imaging. Different nanostructures, growth patterns are attracting the attention of many researchers due to their importance connected to some fractal growth phenomena, crystallography research and their wide applications in micro- and nanodevices. The growth of Different nanostructures is also a profound example among a wide range of pattern-forming phenomena in nature and biology. Various methods have been developed for synthesizing different crystal dendrites, electrochemical deposition as a simple, rapid and economical method has shown a powerful ability to control the crystallization engineering of nano materials and the preparation of large area thin films.Herein, we studied the electrochemical controllable growth of the different shapes and the orientation of crystallites of the Au,Ag and its alloy , nanostructures without any template, surfactant directed. It can be observed that silver dendrites were obtained in a large quantity and good uniformity by a simple electrochemical route.The main results and conclusions are summarized as follows:1. we studied the electrochemical controllable growth of the shape and the orientation of crystallites of the Ag dendritic nanostructures without any template, surfactant directed. It can be observed that silver dendrites were obtained in a large quantity and good uniformity by a simple electrochemical route. In the silver dendrites, the diameter of the trunk is around 100 nm with its length up to 16μm, the length of the branch can reach 3μm. And the crystal structures for the trunk and branches in the silver dendrites were characterized by selected area electron diffraction (SAED). Furthermore, we also investigated the effects of the growth conditions on the morphology of silver dendrites, especially the growth tendency of Ag dendrites at different controlled temperature. The results show that experimental temperature play an important role in the formation of Ag dendrites hierarchical structure during the electrodeposition process. The temperature range of 25-60℃is suitable for the formation of silver dendrites. This may be due to the fast growth of silver Ag dendrites was affected by ions diffusion speed in the electrolyte. In addition, we also initially investigated the interesting hierarchical structure of the Ag dendrites used as SERS substrates.2. The flower like nanstructure crystals of Au and its alloy Au-Ni,Au-Co,Au-Cu,were prepared by a simple low-cost electrochemical approach. The diameter of the crystal can be easily controlled via simply controlling the deposition time.We also investigaed the effect of defferent metal ions to the formation of the crystal.the results showed that the shape of the production could be controlled via adding different metal ions. More importantly,such crystals have particular morphologies and surfaces,which could have potential applications in bioelectrochemistry, superhydrophobicmaterials, etc.3. A novel modified electrode was prepared by immobilizing Au-Ni alloy flower -like nano particles onto glassy carbon electrode. The voltammetric behaviors of uric acid (UA) and ascorbic acid (AA) were studied at the Au-Ni alloy modified electrode. Compared to glassy carbon, this modified electrode electrocatalyzes oxidation of UA and AA, which increasing their oxidation currents and reducing the overpotentials greatly. Furthermore, this Au-Ni alloy flower like nano partitles modified electrode resolved the overlapping voltammetric response of UA and AA into two well-defined voltammetric peaks, their anodic potential difference (ΔE_P) was about 180 mV. All results shows that this modified Electrode has a good electrocatalytic ability to UA and AA, and has an excellent selectivity towards UA even in the presence of high concentration of AA.The Au-Ni alloy flower like nano partitles have been used to immobilize Hemoglobin(Hb) for assembling into the modified electrode and study their direct electrochemical behaviors. It was observed from the cyclic voltammetric data that Au-Ni alloy flower like nano partitles could effectively promote the direct electron transfer between the adsorbed Hb protein redox site and the electrode surface.