Reaction uses carbon dioxide to make carbon-based semiconductor

A materials scientist at Michigan Technological University has discovered a chemical reaction that not only eats up the greenhouse gas carbon dioxide, it also creates something useful. And, by the way, it releases energy.

Making carbon-based products from carbon dioxide is nothing new, but carbon dioxide molecules are so stable that those reactions usually take up a lot of energy. If that energy were to come from fossil fuels, over time the chemical reactions would ultimately result in more carbon dioxide entering the atmosphere—defeating the purpose of a process that could otherwise help mitigate climate change.

Professor Yun Hang Hu’s research team developed a heat-releasing reaction between carbon dioxide and Li3N that forms two chemicals: amorphous carbon nitride, a semiconductor; and lithium cyanamide, a precursor to fertilizers.

“The reaction converts carbon dioxide to a solid material,” said Hu. “That would be good even if it weren’t useful, but it is.”

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Researchers: Carbon better than copper for TSVs

Three-dimensional chip stacks are better connected with through-silicon-vias (TSVs) filled with carbon nanotubes instead of copper, according to researchers at Chalmers University of Technology in Gothenburg, Sweden.

TSVs promise to speed up the communications among all the chips that make up an electronic system by stacking them in 3-D instead of laying them out flat on circuit boards. Unfortunately, filling the vias with copper causes problems with thermal expansion, since copper expands more than the surrounding silicon. Carbon nanotubes could solve this problem.

“Carbon nanotubes have much better properties than copper, both in terms of thermal and electrical conductivity”, said Kjell Jeppsson, a member of the Chalmers research team. “They expand about the same amount as the surrounding silicon while copper expands more, which results in mechanical tension that can cause the components to break.” Other team members included Teng Wang and Johan Liu.

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