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Posted: January 9, 2008
Scientists use nano manufacturing processes to construct new materials with tailored properties
(Nanowerk News) Scientists have only been able to take naturally occurring materials so far when it comes to their physics and chemical properties. What they do in their natural form is simply what they do. They can't do any more by themselves, though compounds combining several different materials have been used to extend base abilities. Now, scientists are finding out that through nano construction processes, they can custom build new materials that don't naturally occur in nature, with some amazing properties.
For example, researchers at The University of California, Santa Cruz have developed a thin-film composite material constructed nano-layer by nano-layer. It's being customized through experimental research to be a most amazing solar cell. The results are a set of variable controls over what exists at which layer, how it generates, captures, transports and stores free electrons. By varying traits at various levels by varying the materials, the end result is something that isn't naturally occurring, but is more conducive to engineering needs.
In their tests, an increase of 3x the efficiency was achieved when they prepared specially constructed thin films from 150 to 1100 nm for solar cell applications. They included titanium dioxide particles with an average size of 100 nm, doped with nitrogen and specially formed quantum dots made of cadmium selenide. The end result was a material which, according to the researcher's early theories, allows the electrons to "hop around more easily". This allows their converted energy (into electrons) to evacuate the location where they are formed more quickly, thereby allowing more of them to be formed faster.
The team is also looking beyond raw solar cell applications. They would like to see a composite material which could be constructed to directly utilize the sun's energy to convert water into hydrogen and oxygen. Such a material would provide a highly efficient, 100% green method of generating hydrogen anywhere they're sunlight, and that includes applications which are necessarily in otherwise undesirable real-estate locations, such as deserts. And with the ability to vary the band gap width through this kind of specialized nano construction, this reality seems closer than ever before possible.
Other uses incldue a potential for converting carbon dioxide into hydrocarbon fuels, such as methane, and other such conversion applications.
The team's funding was provided by the U.S. Department of Energy, the National Science Foundation of China, the University of California Institute for Mexico and the United State's UC-MEXUS. Research was carried out under supervision by Jin Zhang, professor of chemistry at the University of California, Santa Cruz.