Faster release of hydrogen.(MATERIALS)

Researchers at the Pacific Northwest National Laboratory (PNNL), USA, have used silicon oxide (silica) and nanotechnology in a novel system that releases hydrogen from a solid compound at much faster rates than was previously possible.

Normally, the solid compound--ammonia borane--discharges hydrogen at a slow rate of release (which is carried out at temperatures below 80[degrees]C).

However, by making the ammonia borane as a nano-sized particle, a system was devised in which the hydrogen was released approximately 100 times faster compared with conventional bulk material, the researchers say.

In the system, the scientists first dissolve the solid compound in a solvent and then add the solution to nanoscale mesoporous silica, which acts as a scaffolding material.

The capillary action of the porous material pulls the ammonia borane into the pores of the support. When the solvent is removed, nanosized pores--about 6.5 nm in diameter--filled with ammonia borane are left.

Based on computational thermodynamic analysis, the researchers believe the process may eventually be designed to be reversible, which would allow the storage material to be regenerated and provide a sustainable hydrogen storage compound with a longer lifetime.

A patent is pending on the process.

For further information, contact: Pacific Northwest National Laboratory, PO Box 999, MS K2-44, 902 Battelle Boulevard, Richland, WA 99352, USA; tel: +1-509-375-2121; Internet: www.pnl.gov