Carbon materials can be made-to-order with a range of pore sizes, say chemists in France.

Man-made porous carbon materials are used in electrical components, as adsorbents in water purification, as hydrogen storage materials and as catalysts. Each different application demands the right kind of pores.

Fabrice Leroux at Université Blaise Pascal and colleagues sandwiched vinyl benzene sulfonates between layered double hydroxides. After polymerisation of the vinyl sulfonates, the sandwich structure was broken down using heat. Inorganic residues were dissolved with acid to leave a porous carbon product. 

The resulting carbon material has a higher surface area than carbons made by other methods, said Leroux. The materials end up with two kinds of pores: micropores, up to 2 nm in size, and mesopores, from 2 to 50 nm. Leroux said the presence of mesopores will allow the carbon to be used in capacitors.

The porosity and other properties of the carbon materials can be fine-tuned by altering various stages of the synthesis, said Leroux. 

Eduardo Ruiz Hitzky, at the Materials Science Institute of Madrid, Spain, said that these carbon materials showed 'a remarkably high specific surface area' and that their textural properties open the way to potential applications such as hydrogen storage.

Michael J Smith