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New Artificial Material Mimics Photosynthesis to Create Clean, Self-Sustaining Energy Source

PETER DOCKRILL
9 NOV 2015

It’s one of the holy grails of scientific research: discovering a way of replicating the natural process of photosynthesis, such that light could be easily converted into energy for other purposes, just like a plant does. And now researchers in the US have discovered an artificial material that lets them mimic this system to create a clean, sustainable source of power.

 

Researchers at Florida State University have discovered a method of using manganese oxide – also known as birnessite – to capture sunlight and then use that solar energy to create an oxidation reaction, breaking down water (H2O) into hydrogen (H) and oxygen (O2). Oxidation occurs during photosynthesis, and by replicating this part of the natural process, we might be able to produce energy in new ways via a simple, practical mechanism.

“In theory, this should be a self-sustaining energy source,” said Jose L. Mendoza-Cortes, assistant professor of chemical engineering. “Perhaps in the future, you could put this material on your roof and it could turn rain water into energy with the help of the sun.”

Best of all, using manganese oxide in this kind of way would be an entirely carbon-neutral method of producing energy sources like hydrogen fuel, and wouldn’t have any negative impacts on the environment. “You won’t generate carbon dioxide or waste,” said Mendoza-Cortes.

Once produced, hydrogen can be used as a fuel and burned with oxygen to form H2O, releasing energy in the process. But usually the creation of hydrogen fuel is powered by burning fossil fuels, which is why this new technology is so exciting.

When looking to find a material that would be able to facilitate the process of breaking down water but also capturing the energy from the Sun, the researchers faced two initial challenges: finding a material that didn’t rust due to exposure to the water, and also one which wasn’t too expensive to create.

The answer Mendoza-Cortes and his team came up with – which is described in their paper in The Journal of Physical Chemistry – was to develop a multilayered material out of manganese oxide. However, it was only when they stripped back the multiple layers to a single layer that they struck what they were looking for. When they did this, the material was able to trap light at a much faster rate.

How is this possible? According to the researchers, the single layer of the manganese oxide material provides what’s called a direct band gap, whereas multiple layers constituted an indirect band gap. Light penetrates different sorts of materials differently, but its energy is only effectively captured and stored by materials with a direct band gap.

What’s remarkable about the material the researchers developed in this instance is that it is more effective at capturing energy when there is only a single layer of it – a desirable outcome for the purposes of any potential real-world applications, as it will be cheaper and easier to manufacture.

“This is why the discovery of this direct band gap material is so exciting,” said Mendoza-Cortes. “It is cheap, it is efficient and you do not need a large amount to capture enough sunlight to carry out fuel generation.”

It’s early days yet and there’s no word so far on when we can expect to see this kind of material manufactured for domestic purposes, but with the researchers already envisaging potential applications like household roof-top energy generators, it’s an incredibly exciting development.