Scientists use cobalt catalyst to produce hydrogen from water

Lead author of the research Dr Erwin Reisner, an EPSRC research fellow and head of the Christian Doppler Laboratory at Cambridge University, said: ‘A H₂ evolution catalyst that is active under elevated O₂ levels is crucial if we are to develop an industrial water-splitting process — a chemical reaction that separates the two elements that make up water. A real-world device will be exposed to atmospheric O₂ and will also produce O₂ 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 carbon dioxide as a by-product, making it neither renewable nor clean. A green process such as sunlight-driven water splitting is required to produce green and sustainable hydrogen.

According to the university, 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 platinum are too expensive and cheaper alternatives are typically inefficient. Very little progress has been 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 said in a statement: ‘Until now, no inexpensive molecular catalyst was known to evolve H₂ 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 oxygen are produced simultaneously.