The Research On Preparation Of Nanoporous Metal By The Soluable Aerogels Template

As a new class of materials with special structure and function, nanoporous metals combine properties of traditional metals such as good thermal and electrical conductivity, catalytic activity, and ductility with properties characteristic of nanoarchitectures such as aerogels with high surface area, low density and high strength-to-weight ratio. As such, nanoporous metals have attracted great attention in the field of electrochemical, hydrogen stroge, separation and filtration, optical and biological applications. Moreover, some high-Z porous metal foams with light weight and high mechanical strength can provide a novel target materials for high-energy density physics experiments like ICF?Inertial Confined Fusion?. Currently, the most common strategies to make porous metals are mainly based on dealloying, combustion, templating, sol-gel assembly, electrochemical etching and laser ablation. Among them, templating is a powerful method to control porosity within metals by using sacrificial inorganic or organic materials as templates, which,however, is usually limited to prepare nanoporous metal powder and film, or existing the impure product shortcomings after removing the template at high temperature. This paper innovativly put forward a kind of method to preparing nanoporous metals with a self-supporting structure, which used the solublecellulose and SiO₂ aerogels as a template. The research contents in this thesis mainly include the following parts:?1? The nanoporous nickel has been prapared by electroless plating using SiO2 aerogel as template, whose structure and morphology in different prapering process parameters are characterized by means of scanning electron microscope?SEM?, transmission electron microscopy?TEM?, X-ray powder diffraction?XRD?, inductively coupled plasma atomic emission spectrometry?ICP-AES?, N2 adsorption and so on.?2? The uniform activation- sensitized SiO₂ has been prapared and used for template to prepare nanoporous copper through electroless plating, which verifing the SiO₂ areogel is versatile in preparation of nanoporous metals. In addition, we have studied the the main factors influencing the morphology and structure nanoporous copper by changing the chemical plating temperature and time.?3? We have prepared cellulose aerogel sucessfully and synthesized nanoporous nickle by using it as a template, and obtainednanoporous nickel sheet with self-supporting and high specific surface area after the nickle powder beening pressed. We have also studied the effects of plating time and mechanical compression on the structure and morphology of nanoporous nickel metal.From the study above, we have reached the following conclusions:?1? Nanoporous nickel can be successfully synthesized by electroless plating when using SiO₂ aerogel as a template, the resulting product is a copy of the template structure. The Ni content of SiO₂/Ni has been increased with the electroless timeincreasing, and the Ni content of SiO₂/Ni composite will beup to 55.82wt% at 18 d. The surface area, total volume and micropore volume of the nanoporous nickel are all increasing firstly and then decreasing with the increasing plating timeafter the template beening removed, and the electroless temperature is also playing a great role in the morphology and structure of nanoporous nickel. When the time is 12 d and the temperature is 35?, the surface area of the obtained nanoporous Ni with nanoscale pore structure can up to 120.54m2/g, whosecoercive force?Hc? is 321.78 Oehere.?2? The SiO₂ aerogel template can also have applicability on the preparation of nanoporous Cu. The Cu particles can be successfully incorporated in the SiO₂ aerogel skeleton by electroless method, and the Cu content of the SiO₂/Cu composite has been increased with the electroless plating time and temperature increasing. The plating time is longer, the deposited Cu nanoparticles have a tendency to become Cu O. When the palting time is up to 30 d, the Cu paticles will be melted and connected to a lager paticle after being dealt at 300?, which have a microstructure and evenly distributed in the template. The nanoporous Cu has been obtained after the SiO₂ aerogel being removal, but the Cu nanoparticles are easily been oxidized to Cu O.?3? The cellulose aerogel with high specific surface area of 712.m2/g can be successfully prepared by re-gelling and be dissolved by Li OH / urea solution, which can be used as a template to prepare nanoporous metal. We can successfully obtain cellulose / Ni complexe by electroless method, and the purity of nanoporous Ni obtained from the template removal is as high as 98.7%, which can demonstrate that the adequate removal of template.With the increase of electroless time, both of the specific surface area and the total pore volume of the obtained nanoporous Ni increase firstly and then decrease. When the time is 6d, the specific surface area of the nanoporous Ni is highest. thetableting has a great effect on the structure and morphology of the nanoporous Ni. The specific surface area of the nanopporous Ni will increase and we can get a nanoporous Ni with a self-supporting structure after being pressed under 4Mpa, whose shape is determined by the different mold.