Thursday, August 16, 2012
Australia - Nanostructures To Harness Hydrogen Energy Potential
Engineers in Australia have demonstrated that hydrogen can be released and reabsorbed from a promising storage material, overcoming a major hurdle to its use as an alternative fuel source.
For the first time, engineers in Australia have demonstrated that hydrogen can be released and reabsorbed from a promising storage material, overcoming a major hurdle to its use as an alternative fuel source.
Considered a major a fuel of the future, hydrogen could be used to power buildings, portable electronics, and vehicles – but this application hinges on practical storage technology.
Lightweight compounds known as borohydrides (including lithium and sodium compounds) are known to be effective storage materials but it was believed that once the energy was released it could not be reabsorbed. This critical limitation made sodium borohydride an oft overlooked chemical compound for energy storage.
In a paper published recently in the journal ACS Nano, researchers from the Materials Energy Research Laboratory in nanoscale (MERLin) at the University of New South Wales (UNSW) synthesized nanoparticles out of sodium borohydride and encased these inside nickel shells.
“No one has ever tried to synthesize these particles at the nanoscale because they thought it was too difficult, and couldn’t be done. We’re the first to do so, and demonstrate that energy in the form of hydrogen can be stored with sodium borohydride at practical temperatures and pressures,” said senior author Dr. Kondo-Francois Aguey-Zinsou.
In this study, the researchers observed remarkable improvements in the thermodynamic and kinetic properties of their unique “core-shell” nanostructures. This means the chemical reactions needed to absorb and release hydrogen occurred faster than previously studied materials, and at significantly reduced temperatures – making possible application far more practical.
In its bulk form, sodium borohydride requires temperatures above 550 °C just to release hydrogen. Even on the nanoscale the improvements were minimal. But with their core-shell nanostructure, the researchers saw initial energy release happening at just 50 °C, and significant release at 350 °C.
“By controlling the size and architecture of these structures we can tune their properties and make them reversible – this means they can release and reabsorb hydrogen,” said Aguey-Zinsou.
“We now have a way to tap into all these borohydride materials, which are particularly exciting for application on vehicles because of their high hydrogen storage capacity.”
The paper can be downloaded at: Christian ML et al. (2012) A Core-Shell Strategy Leading to High Reversible Hydrogen Storage Capacity for NaBH4.