Title : Nanostructured metallic glasses and their powders as catalytic, chemical and biological materials
Abstract:
Here I am going to present the results of our long-term research activities on nanostructured metallic glasses and metallic glassy powders applicable as catalytic, chemical and biological materials. In particular, Au-based nanostructured metallic glasses produced by magnetron sputtering with a large surface area exhibited a high catalytic activity on the oxidation of the organosilane compounds with water. The catalyst was easily recoverable and was demonstrated to be used at least five times without loss of its activity. A nanograined Pd78Si22 metallic glass was also produced which is also applicable for other reactions. In addition to the nanostructure-induced catalytic activity, these materials sustain good mechanical properties of a metallic glassy structure, showing a high hardness, good deformability and a low elastic modulus.
Ti- and Zr-based nanostructured metallic glasses exhibited excellent biocompatibility. A submicron-nanometer-sized hierarchical glassy structure of a Ti34Zr14Cu22Pd30 nanostructured metallic glass was used to tune the osteoblasts cell bioactivity. Our experimental results provide strong evidence that such a structure is extremely beneficial for cell attachment and proliferation. The Zr62.5Pd37.5 metallic glassy alloy exhibit a good thermal stability versus crystallization and good resistance to oxidation in dry air up to 573-673 K. The samples also show a very high corrosion resistance and spontaneous passivation in a simulated body fluid. The sample also exhibit catalytic activity in Suzuki-coupling reaction. The osteoblast cells cultivation on the nanoglass was also used to prove its good biocompatibility. The material has potential in biochemistry for biosensors and artificial tissue engineering.
Fe-based metallic glass powders were found to completely decompose the C32H20N6Na4O14S4 in aqueous solution in short time, about 200 times faster than the conventional Fe powders. MgZn-based metallic glassy powders also exhibited excellent ability in degrading azo dyes as typical organic water pollutants. Their azo dye degradation efficiency is about 1000 times higher than that of commercial crystalline Fe powders, and 20 times higher than their crystalline counterparts. The high Zn content in the amorphous Mg-based alloy enables a greater corrosion resistance in water and higher reaction efficiency with azo dye compared to crystalline Mg. Even under complex environmental conditions, in solutions with different pH, in a solution that contains several different azo dyes, at relatively low temperature and after exposure to air for a long time, the MgZn-based metallic glass powders retain their high reaction efficiency.
The above-described materials will be discussed in comparison with the metallic glassy samples for catalytic reactions produced by other research groups.
