Breakthrough in fuel cell technology?

New type delivers energy and fine chemicals waste-free from renewable resources

Fuel cell © Forschungszentrum Jülich
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A fuel cell type newly developed by an international research team delivers energy and fine chemicals from renewable resources without waste. As the scientists report in the journal "Angewandte Chemie", the so-called organometallic fuel cell, alcohols and sugars convert efficiently into carboxylic acids. Carbon dioxide is not released.

Unlike the established alcohol fuel cells, the direct alcohol fuel cell and the enzymatic biofuel cell, the organometallic fuel cell (OMFC) works on a completely different principle. Success secret is a special molecular complex of metal rhodium that acts as an anode catalyst.

Catalytic cycle

The scientists around Hansjörg Grützmacher, Francesco Vizza and Claudio Bianchini of the ETH Zurich as well as colleagues of the Consiglio Nazionale delle Ricerche (CNR) in Sesto Fiorentino, Italy deposit the complex finely distributed on carbon powder as carrier. The interesting thing is that the active catalyst forms during the chemical reaction - and it gradually changes in the course of the catalytic cycle.

In this way, from a single metal complex different catalysts are formed, which are specific to the individual reaction steps: the conversion of alcohol such as ethanol in the corresponding aldehyde, from aldehyde to the corresponding carboxylic acid (eg acetic acid), also for the transfer of protons (H + ) and electrons. Not only alcohols, but also sugars like glucose can be converted in this way.

Breakthrough in fuel cell technology?

The researchers hope that their new approach could prove to be a breakthrough in fuel cell technology. A particular advantage of the new technique is that molecular metal complexes are soluble in various solvents and can thus be distributed extremely finely on very small surfaces. Nevertheless, they deliver a surprisingly high power density. display

This, according to chemists, could be a way to further miniaturize fuel cells, making them accessible, for example, as a power source for biological applications such as cardiac pacemakers and biosensors, such as in vivo tracking of metabolic processes.

Tailored catalyst structure

By cleverly combining a tailor-made molecular catalyst structure with a suitable carrier material, the researchers are now able to develop fuel cells that selectively and specifically convert starting materials with multiple alcohol groups into very specific valuable fine chemicals, without that waste products arise. A task that is extremely difficult to achieve with traditional methods.

(idw - Society of German Chemists, 28.09.2010 - DLO)