Breakthrough

Hydrogen energy breakthrough replicates photosynthesis

Researchers have split water into hydrogen and oxygen by replicating how plants use photosynthesis to make carbohydrates.

The breakthrough could revolutionize the renewable energy industry by making hydrogen, touted as the clean, green fuel of the future, cheaper and easier to produce on a commercial scale.

The team of Australian and US researchers says their findings, published in the latest Angewandte Chemie International Edition could lead to a cheap and easy way of making hydrogen, which many experts believe is the green fuel of the future.

Fuel cells currently used as alternatives to gasoline-powered engines in vehicles run on hydrogen that is mostly produced from refining fossil fuels. The new process would rely on renewable sources, rather than oil or natural gas, and use no electricity, said the scientists.

Professor Leone Spiccia, of Monash University's School of Chemistry says the team has mimicked the process of photosynthesis, whereby plants convert light and atmospheric carbon dioxide into energy.

Although scientists have been able to split water into hydrogen and oxygen for years, current techniques use expensive chemicals as the catalyst which prohibits any move to a commercial product.

The new system involves an electrode coated with a proton conductor that is then impregnated with a form of manganese.
Nature's recipe

Manganese clusters are essential to a plant's ability to use water, carbon dioxide and sunlight to make carbohydrates, Spiccia says.However instead of creating carbohydrates, the team have used nature's recipe to split water into its two elements, oxygen and hydrogen.

"We have copied nature, taking the elements and mechanisms found in plant life that have evolved over three billion years and recreated one of those processes in the laboratory," he says.

The system uses manufactured copies of these manganese clusters, known as cubanes, which were developed by co-author Princetown University Professor of Chemistry Charles Dismukes.

Spiccia says they discovered when the cubanes, which are about 1.5 nanometres square, were contained within the proton conductor they became more stable and less likely to deteriorate.

"When you take water and start to oxidise it you get radical matter that is very reactive and destructive and generally kills off the catalyst," Spiccia says."We've hit on something that's stopped that side of the reaction." He says the mechanism by which the hydrogen gas is created is still being studied.

Tests have shown the catalyst assembly is still active after three days of continuous use, producing oxygen and hydrogen gas with the help of sunlight and 1.2 volts of electricity.
Spiccia says their research is different in its approach to other water splitting research because it copies nature by using similar processes and chemicals to those used in plants.

The team plans to further that connection by using chlorophyll-like molecules to harvest light rather than an electric current. Researchers have split water into hydrogen and oxygen by replicating how plants use photosynthesis to make carbohydrates. ... more

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