Items Tagged With Catalysis

Researchers at the Advanced Technology Institute, University of Surrey have reversed the growth of carbon nanotubes from catalysts, using electron beam irradiation in an electron microscope. High resolution imaging of this reverse process led to the conclusion that carbon nanotube growth is essentially a surface-driven process.

Silicon nanowires can help to further reduce the size of microchips. Scientists at the Max Planck Institute for Microstructure Physics in Halle have for the first time developed single crystal silicon nanowires that fulfil the key criteria to this end. The researchers used aluminium as a catalyst to grow the nanowires. To date, scientists have usually deployed gold for this purpose. However, even traces of the precious metal have a drastically detrimental effect on the function of semiconductor components. This is not the case with other metals, which catalyse the process, but only at temperatures that would not enable economically viable processes. On the other hand, aluminium is an effective catalyst even at relatively low temperatures and does not impair the quality of electronic components (Nature Nanotechnology, doi: 10.1038/nnano.2006.133).

Gold has unexpected properties: it can act as a catalyst and transform carbon monoxide (CO) to carbon dioxide (CO₂) when it comes in the form of nanoparticles. Gold suddenly enhances desired chemical reactions as a catalyst for example in the removal of odours and toxins or to clean automotive exhaust gases. Researchers from Switzerland, UK, the USA and the ESRF (Grenoble) have monitored the catalytic process and proposed an explanation for the high catalytic activity of gold. They have published their results in the journal Angewandte Chemie.