Only carbon from the Group 14 elements forms stable double bonds with oxygen under normal conditions. When frozen, carbon dioxide is known as "dry-ice". A non-molecular single-bonded crystalline form of carbon dioxide (phase V) exists at high pressure according to Italian and French researchers.1

Amorphous forms of silica (a-SiO₂) and germania (a-GeO₂) are known at ambient conditions but only recently has an amorphous, silica-like form of carbon dioxide, a-CO₂. This is labelled a-carbonia and made by compression of CO₂ at room temperature at pressures between 40 and 48 GPa (that's a staggering 400-500 thousand atmospheres).

During this compression, infrared spectra at temperatures up to 680 K show the progressive formation of C–O single bonds and the simultaneous disappearance of all infrared bands associated with molecular CO₂. Raman and synchrotron X-ray diffraction measurements confirm the amorphous character of the CO₂. Vibrational and diffraction data for a-SiO₂ and a-GeO₂ are closely related and calculations also suggest shows that a-CO₂ is structurally homologous to a-silica (a-SiO₂) and a-germania (a-GeO₂).

This research helps to understanding the nature of the interiors of gas-giant planets where carbon dioxide may be squeezed at very high pressures. Maybe it could be used to make very hard glass because it is expected to be very stiff rather like diamond. The researchers ponder whether "small amounts of these new glasses could be of interest for technology applications like hard and resistant coatings for micro-electronics, for example."

• 1. Amorphous silica-like carbon dioxide,
  Santoro, Mario, Gorelli Federico A., Bini Roberto, Ruocco Giancarlo, Scandolo Sandro, and Crichton Wilson A.
  , Nature, 6/2006, Volume 441, Issue 7095, p.857 - 860, (2006)
  

There seems to be a possibility that nickel compounds might help in the electrolysis of water, the reaction at the centre of hydrogen fuel cells. Researchers at the Joseph Fourier University in Grenoble, and at the French Atomic Energy Commission in Gif-sur-Yvette and attached a nickel compound that mimics hydrogenase enzymes (catalysts) and attached it to the surface of carbon nanotubes. This maximises the catalyst's surface area. The resulting material was tested using a proton-exchange membrane and produced hydrogen from a sulphuric acid solution. The result is only 1% as efficient than commercial platinum catalysts but is stable under typical fuel cell conditions, justifying further study.1

• 1. From Hydrogenases to Noble Metal-Free Catalytic Nanomaterials for H2 Production and Uptake,
  Le Goff, A., Artero V., Jousselme B., Tran P. D., Guillet N., Metaye R., Fihri A., Palacin S., and Fontecave M.
  , Science, 12/2009, Volume 326, Issue 5958, p.1384 - 1387, (2009)