FuelCellsWorks

Researchers at the Dalian Institute of Chemical Physics in China and the National University of Singapore have improved the performance of ammonia borane (AB) as a material for hydrogen storage—potentially for on-board storage in a vehicle—by developing a new method for doping AB with nanosized Co- and Ni-based catalysts.
Experimental results showed that the catalyst-doped AB samples can release approximately 5.8 wt% H2 at a temperature as low as 59 °C. Moreover, the dehydrogenation does not bring any detectable borazine or foaming.

A paper on their work was published online 27 April in the ACS journal Chemistry of Materials.

Ammonia borane (NH3BH3) has been of interest as a hydrogen storage material for a number of years because of its high hydrogen content (19.6 wt%). In 2007, an independent technical review panel convened at the behest of the US Department of Energy to consider the technical status and progress of R&D on the hydrolysis of sodium borohydride (NaBH4) for on-board vehicular hydrogen storage unanimously recommended a “no-go” to further funding for the development of that material, while also suggesting further work on ammonia borane. (Earlier post.)

However, dehydrogenation—releasing the hydrogen—from AB usually required temperatures of more than 100 °C, making it too hot for polymer-based fuel cells. Other issues with its use were the release of other gases which could poison the hydrogen and instability (rapid expansion or turning into foam).

Ping Chen and colleagues doped a two mole percent Co- or Ni-based catalyst to AB using a co-precipitation method they developed. With the only added weight to AB being the 2.0 mol % catalytic additives, the hydrogen capacity of the system is not sacrificed significantly.

Resources

Teng He, Zhitao Xiong, Guotao Wu, Hailiang Chu, Chengzhang Wu, Tao Zhang and Ping Chen (2009) Nanosized Co- and Ni-Catalyzed Ammonia Borane for Hydrogen Storage. Chem. Mater. DOI: 10.1021/cm900672h

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