Topic of the Moment: fuel cells

Research published in Nature shows that ‘wonder material’ graphene is permeable to protons, suggesting it may have applications for hydrogen-based technologies such as fuel cells.

The Toyota FCV concept car, powered by hydrogen fuel cells
Credit: Mytho88
Concept car powered by hydrogen fuel cells

Fuel cells convert hydrogen and oxygen into water, producing electricity in the process. The principle is the reverse of the better known splitting of water into its components by applying an electric current, and was first suggested as a means of generating electricity by William Grove in 1838.

Since the only byproducts are heat and water, they’re sometimes touted as a possible environmentally friendly replacement for petrol-powered engines in motor vehicles. The problem is making them efficient and cost-effective.

The type typically considered for transport applications are proton exchange membrane fuel cells.

Hydrogen gas is directed towards an anode, where a catalyst, such as platinum nanoparticles, splits it into a proton and an electron. The protons pass through a membrane towards the cathode, but the electrons must travel along an external circuit – thereby generating an electric current.

At the cathode, the protons and electrons are combined with oxygen, producing water, which then flows out of the cell.

Unlike batteries, which convert stored chemical energy to electricity, fuel cells need a constant supply of hydrogen and oxygen in order to work. While that poses an infrastructure challenge, it does mean that, where electric cars are most useful over short runs, one powered by hydrogen fuel cells could, like a conventional vehicle, travel longer distances without running out of juice.

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