Combining Solar Driven Water Splitting With A Fuel Cell

Researchers at the University of Basel are studying a process combining solar driven water splitting with a fuel cell. A team of researchers led by the University of Basel chemists Catherine Housecroft and Edwin Constable are working together with the Swiss Federal Laboratories for Materials Science and Technology (Empa) to implement the new method.

The team’s research paper has been published in the journal Chemical Communications.

An important factor in creating photo-electrochemical fuel cells is the precise arrangement of the individual components. “If you don’t do this, it’s like throwing all the different parts of a clock into a bag, giving it a shake and then hoping it will be possible to tell the time,” explains Prof. Edwin Constable from the University of Basel.

The process of splitting water (H2O) consists of two partial reactions, which are implemented with the help of different catalysts: water reduction (which produces the H2 and sets loose the O) and water oxidation (which produces the O2). The second is the more challenging of the two reactions, which is why research puts so much effort into the development of efficient and sustainable water oxidation catalysts. Simply stopping at O or ozone isn’t a really good idea.

To determine the perfect arrangement of the catalysts, the Basel-based chemists developed a water oxidation model in their current study which, although powered by electricity, generates the same chemical intermediate states as light. To accomplish this, they used compounds of the chemical element ruthenium as a catalyst. The critical feature is the self-assembly of the individual components in a hierarchical structure. The researchers thus succeeded in simulating fuel cells powered by light radiation. This model allowed them to test the position and efficiency of the individual components.

The ultimate portable and clean fuel is hydrogen, even with storage problems aside, the lure is intense for progress. Combining the solar water splitting and recombining in a fuel cell is interesting. A little storage could make a daylight hours separation operation to fuel cells electrical production run nearly continuously. The other hint is the system could be closed loop allowing no contaminates into the system. That might be an early adopter advantage.

The Swiss team notes they have stability and efficacy in a 10 hour operation before the test system stops. They haven’t set out to work up system stability, but 10 hours right out of the idea point is remarkable.

There are some issues that will stall the system awaiting developments in other material sciences. But these folks may be at a leading edge of what actually comes to market. It will be interesting to see how much energy from the sun gets into a grid.

Artificial photosynthesis for water splitting is one of the most promising approaches we have.