Nanotech Materials Solution Devised for Hydrogen Storage

Kondo-Francois Aguey-Zinsou (University of New South Wales)

Chemical engineers at University of New South Wales in Australia synthesized and demonstrated a material that absorbs, releases, and reabsorbs hydrogen, a key step in advancing hydrogen as an alternative fuel source. The team from the university’s Materials Energy Research Laboratory in nanoscale (MERLin) published its findings last week in the journal ACS Nano; paid subscription required.

The ability to store hydrogen is considered a key enabling technology for advancing fuel cells in transportation, stationary, and portable energy applications. The U.S. Department of Energy has set its sights on vehicular hydrogen storage systems that allow for a driving range of greater than 300 miles while meeting packaging, cost, safety, and performance requirements competitive with current vehicles.

Chemical engineering professor Kondo-Francois Aguey-Zinsou  (pictured left) and graduate student Meganne Christian synthesized nanoparticles of the chemical compound sodium borohydride and encase the nanoparticles inside nickel shells. Borohydrides are lightweight compounds considered effective as storage materials for hydrogen. The researchers say sodium borohydride had been overlooked because its inability to reverse the release of hydrogen. In addition, the release of hydrogen from sodium borohydride in bulk form could only be done at temperatures exceeding 500 degrees C.

The New South Wales team devised a process for synthesizing particles of sodium borohydride no more than 30 nanometers across; 1 nanometer equals 1 billionth of a meter. Creating the nanoscale form of sodium borohydride lowers its melting point, making it possible to release hydrogen at a somewhat lower temperature of 400 degrees C.

To address the need to reabsorb hydrogen, Aguey-Zinsou and Christian encased the nanoparticle in nickel chloride, which makes it possible to release and reabsorb hydrogen. “By controlling the size and architecture of these structures,” says Aguey-Zinsou, “we can tune their properties and make them reversible; this means they can release and reabsorb hydrogen.” This core-shell structure also allows for release of hydrogen at lower temperatures, sometimes as low as 50 degrees C, but more likely at 350 C.

In addition to releasing hydrogen at lower temperatures, the core-shell structure exhibits properties that make the chemical reactions needed to absorb and release hydrogen operate faster than with previously studied materials. “No one has ever tried to synthesize these particles at the nanoscale because they thought it was too difficult, and couldn’t be done,” says Aguey-Zinsou, adding the their discovery demonstrates “energy in the form of hydrogen can be stored with sodium borohydride at practical temperatures and pressures.”

Read more:

• National Lab Develops Demonstration Community Fuel Cell
• Low-Cost Nanoscale Catalyst Splits Hydrogen from Water
• Hydrogen Power Utility Vehicle Practical, Not Cost-Effective
• Liquid-Based Hydrogen Storage Material Developed
• Nanoparticle Size Affects Hydrogen Release in Fuel Cells

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