A UK-led European project is attempting to improve the properties of biofuel cells (BFCs) and microbial fuel cells (MFCs) by creating hybrid inorganic-organic electrodes.
Ultimately it could lead to things such as hydrogen fuel cells that are more efficient, easier to make and not reliant on expensive platinum catalysts.
BFCs use enzymes to catalyse the separation of electrons from a parent molecule to then transport it round an electrolyte barrier, while MFCs use whole living bacteria to do this task. Although the basic technology has been around for decades, it has yet to find commercial success.
Dr Lars Jeuken and colleagues from Leeds University believe part of the problem is related to the electrodes, which are generally the conventional metallic or graphite type.
‘At the moment it’s a bit of black-box approach: you take the bacteria or enzymes, you incubate with the solid electrode surface and hope for the best,’ Jeuken told The Engineer. ‘We’re really trying to understand what happens at this interface and trying to optimise it to improve electron conductivity.’
The group has been awarded a £1.42m grant from the European Research Council to create better electrode interfaces and will also contribute to a new Interdisciplinary Centre for Microbial Fuel Cells (ICMFC) with Sheffield and York universities.
‘One of the limiting factors of MFCs is that the electrons have to travel too far a distance to be efficient, so we’re just trying to make the whole microbe colony on the electrodes more conducting and attaching the electrodes in a better way to the microbes,’ Jeuken said.
In the EU project, Jeuken and colleagues will attempt to use biological cell membranes embedded with enzymatic proteins (to perform fuel catalysis), which are laid on the electrode in such a way that they create a very tight interface with the surface. The UK project, meanwhile, will aim at more synthetic means at this interface by using nanoparticles and nanowires.
Jeuken’s team will then apply the electrode technology it develops to bio-based hydrogen fuel cells and light-harvesting fuel cells for the purposes of generating electricity.
These will hopefully have a number of advantages over hydrogen fuel cells currently on the market.
‘If you can make a hydrogen fuel cell where the catalysts are specific — one specific for hydrogen and the other for oxygen — then you can have the two wires in one big vessel and you do not need a membrane in the middle,’ Jeuken said. ‘From an engineering perspective, the membrane is really difficult and really limiting.’