Nature could provide us with the tools to help us power and clean-up after the cars of the future, according to Italian scientists. The team has shown that amino acid-based molecules can be used to store methane, hydrogen and carbon dioxide efficiently.

Piero Sozzani and colleagues from the University of Milan Bicocca have used nanoporous crystalline dipeptides to absorb and store these three gases. Their simple dipeptide systems are made of natural amino acids - valine and either alanine or isoleucine.

 

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Carbon dioxide levels in the atmosphere are a concern as this greenhouse gas is believed to be a major contributor to global warming. One approach for reducing levels is to capture the gas at major sources of emission (such as fossil fuel power plants) for storage underground. Another route is replacing petrol and diesel in cars with cleaner fuels such as methane and hydrogen. Finding new materials to store these gases safely and economically is a major field of research. Most studies explore artificial materials, explains Sozzani. He adds that he hopes his team's results will stimulate further research into using biomaterials for gas storage.

Haoshen Zhou, an expert on gas storage materials from the National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan, says 'this work is the first evidence for the applicability of ultramicroporous biomolecule crystals in gas separation and storage.' He points out that although the hydrogen storage capacity is not particularly high, 'the biocompatible and hydrophobic properties together with the regular pore system and small pore sizes certainly make them a promising group of materials for further research.'

'The rich molecular biodiversity around us could provide an infinite number of other readily available and cheap porous systems,' says Sozzani. 'These materials are intrinsically biodegradable and biocompatible,' he points out. 

In addition to just storing gas, the Italian scientists found that the crystalline dipeptides are selective for carbon dioxide over methane. They suggest that the systems could also be used to purify methane by removing carbon dioxide impurities.

Freya Mearns

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