Bio fuel cells could power portable gadgets: "A hydrogen fuel cell that uses enzymes instead of expensive metal catalysts to drive chemical reactions has been developed by UK researchers.

Enzyme-powered fuel cells could be smaller, simpler and cheaper to make than conventional ones, the researchers claim. They have already powered a digital watch using their invention.

Hydrogen fuel cells are an attractive alternative to conventional batteries because they require only hydrogen and oxygen to produce electricity, and generate only water as a waste product.

Conventional fuel cells work in two stages. Hydrogen is first split into protons and electrons before being combined with oxygen to make water. The reactions take place on separate electrodes, forcing electrons to travel through a circuit in between, generating an electrical current. But these reactions normally rely on electrodes incorporating expensive metal catalysts, such as platinum.

Researchers from Oxford University in the UK used two enzymes, one harvested from bacteria and the other from fungus, to catalyse the same chemical reactions. Each electrode is coated in one of the two enzymes. The bacterial enzymes break down hydrogen as part of their natural metabolism, and the fungal enzymes naturally combine hydrogen with oxygen – usually to break down wood.
Mixed fuel

As the enzymes a"