Scientists at the University of Cambridge have produced hydrogen,
a renewable energy source, from water using an inexpensive catalyst under
industrially relevant conditions (using pH neutral water, surrounded by
atmospheric oxygen, and at room temperature).
Lead author of the research, Erwin Reisner, an EPSRC research
fellow and head of the Christian Doppler Laboratory at the University of
Cambridge, says: “A hydrogen evolution catalyst which is active under elevated
atmospheric oxygen levels is crucial if we are to develop an industrial water
splitting process—a chemical reaction that separates the two elements which
make up water. A real-world device will be exposed to atmospheric oxygen
and also produce atmospheric oxygen in
situ as a result of water splitting.”
Although hydrogen cannot be used as a ‘direct’ substitute for
gasoline or ethanol, it can be used as a fuel in combination with fuel
cells, which are already available in cars and buses. Hydrogen is currently
produced from fossil fuels and it produces the greenhouse gas carbon dioxide as
a byproduct; it is therefore neither renewable nor clean. A green process such
as sunlight-driven water splitting is therefore required to produce ‘green and
sustainable hydrogen’.
One of the many problems that scientists face is finding an
efficient and inexpensive catalyst that can function under real-world
conditions: in water, under air and at room temperature. Currently, highly
efficient catalysts such as the noble metal platinum are too expensive and
cheaper alternatives are typically inefficient. Very little progress was made
so far with homogeneous catalyst systems that work in water and atmospheric
oxygen.
However, Cambridge researchers found that a simple catalyst
containing cobalt, a relatively inexpensive and abundant metal, operates as an
active catalyst in pH neutral water and under atmospheric oxygen.
Reisner says: “Until now, no inexpensive molecular catalyst was
known to evolve hydrogen efficiently in water and under aerobic conditions.
However, such conditions are essential for use in developing green hydrogen as
a future energy source under industrially relevant conditions.
“Our research has shown that inexpensive materials such as
cobalt are suitable to fulfil this challenging requirement. Of course, many
hurdles such as the rather poor stability of the catalyst remain to be
addressed, but our finding provides a first step to produce ‘green hydrogen’
under relevant conditions.”
The results show that the catalyst works under air and the
researchers are now working on a solar water splitting device, where a fuel
hydrogen and the by-product atmospheric oxygen are produced simultaneously.
Fezile Lakadamyali and Masaru Kato, co-authors of the study,
add: “We are excited about our results and we are optimistic that we will
successfully assemble a sunlight-driven water splitting system soon.”
The research was funded by EPSRC, the Christian Doppler Research
Association, and the OMV Group. Their research was published online in Angewandte Chemie International
Edition.
Source: University of Cambridge