| lkgeo1 2006-12-13, 9:25 am |
| Efficient hydrogen production is one step closer
12 December 2006
Japanese researchers have simplified and improved a common method for
generating hydrogen gas, a potentially green energy source.
The approach, developed by Shunichi Fukuzumi's group at Osaka
University, is a modification of existing methods of hydrogen
production where several reactions form a cycle, in which electrons are
transferred from a readily available source to hydrogen ions.
Fukuzumi's adapted method, which he describes as an important step
for the use of hydrogen as a clean energy source, uses a molecule that
combines two stages of the cycle.
Usually, electrons from a donor molecule, such as ethanol, are supplied
to a mediator that can pass them on to a molecule that has been
activated by ultraviolet light. The light-activated molecule then
supplies the electrons to the hydrogen ions in the presence of a
platinum catalyst, generating hydrogen gas.
Fukuzumi's method uses a molecule that plays the role of both the
electron mediator and the light-activated species, transferring
electrons from ethanol to the hydrogen ions. Their results show a
significant increase in the efficiency of the process and the amount of
hydrogen produced.
Hydrogen gas is a promising green energy source because it produces
only water when burnt, rather than climate-changing greenhouse gases;
however, there remain several significant obstacles for the commercial
production of hydrogen as an energy source. The discovery of a cheaper
metal catalyst to replace the expensive platinum system would be
beneficial, but the efficient transfer of electrons to the hydrogen
ions is only half the story.
Fukuzumi used nicotinamide adenine dinucleotide (NADH), an enzyme
cofactor that plays a vital role in energy production in living cells,
as the source of hydrogen ions. A method of generating hydrogen ions
using just water and sunlight represents the next challenge for the
future of hydrogen generation, said Fukuzumi.
Paul O'Sullivan
ReferencesEfficient photocatalytic hydrogen evolution without an
electron mediator using a simple electron donor-acceptor dyad
H Kotani, T Ono, K Ohkubo, S Fukuzumi, Phys. Chem. Chem. Phys., 2007, 9
DOI: 10.1039/b612794k
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