Thread: Artificial leaf converts water in to fuel

Artificial leaf converts water into fuel | COSMOS magazine

SYDNEY: Drawing inspiration from leaves and photosynthesis, two separate research teams have successfully demonstrated improved techniques to convert carbon dioxide and water into usable fuels.
A pair of papers, published today in the journal Science, describe two different approaches to generating fuel: one involving an artificial leaf that can split water molecules to create hydrogen fuel, the other aimed at recycling carbon dioxide.
The first study, a combined effort of researchers from the University of Illinois and U.S.-based company Dioxide Materials, details a more efficient method of reducing carbon dioxide (CO2) to carbon monoxide (CO), a component of synthetic gas fuels.
"Our approach is called artificial photosynthesis. We collect solar energy like plant life collects solar energy, and then use that energy to convert the CO2 into either petrol or some other useful product," said co-author on the first paper Richard Masel, a researcher from Dioxide Materials.
"We were hoping to get 50% energy efficiency but we actually observed over 80%. That makes CO2 recycling feasible," he said.
Recapturing carbon versus recycling
The capture and storage of carbon dioxide produced from fossil fuel emissions has become a prominent issue as a result of concerns about global climate change.
Some examples of storage methods involve the sequestering of carbon dioxide in minerals, or pumping the gas into vacated geological formations such as oil or gas fields. But another option is to try and recycle this gas.
"My view is that burying the CO2 and leaving it for future generations is not a solution to the problem. Instead we need to find ways to recycle CO2 into something useful," said Masel.
To do this, his team has focussed on a technique that will enable the gas to be recycled - broken down into its original components, and converted into fuel.
Improved catalyst changes the game
The concept of using electricity to reduce CO2 is not new, but in previous experiments, high voltages had to be used to overcome the energy of the chemical bonds in carbon dioxide before it could be broken down into oxygen and carbon monoxide.
To get around this, researchers can introduce a catalyst - a substance that accelerates a chemical reaction without itself being affected. This induces an alternative reaction that needs significantly less energy, and therefore less voltage, to break down the carbon dioxide into useful fuel.
In the case of the current study, the researchers discovered that a particular chemical compound known as "EMIM-BF4" was a very efficient catalyst in breaking down carbon dioxide.
Highly accessible technology
One of the benefits of the technology is its ability to be plugged into any external energy source such as a wind farm or solar cell array.
The proposed device would then take in the energy, CO2 and water and produce synthetic gas. This synthetic gas could then be used directly in industrial processes or sent to a refinery to make petrol, researchers explained.
"I think that is a very exciting finding. Lowering the energy requirement for the conversion of CO2 into CO is vital if CO2 is to be efficiently transformed into fuels and other carbon based products," said Leone Spiccia, a chemist from Monash University in Melbourne.
"The approach is complementary to efforts to split water into oxygen and hydrogen fuel. Whilst both approaches have great merit, an advantage of converting CO2 into fuels is that existing engines and distribution infrastructures can be used."
A green alternative
Meanwhile, an effort between American and Dutch industrial researchers has shown that it is possible to use solar energy to split water with cheaper materials than previously thought.
The focus of the second paper to be published in Science is a single device capable of splitting water into oxygen and hydrogen gases by directly harnessing solar energy - an 'artificial' leaf.


"You drop the artificial leaf in a glass of water and hold it up to the Sun. It harnesses the sunlight and then converts it into a solar fuel by splitting water to oxygen and hydrogen," said Daniel Nocera, co-author and chemist from the Massachusetts Institute of Technology near Boston.
Similarly, researchers used catalysts to help achieve the splitting of the water into oxygen gas and hydrogen ions, and then the conversion of the hydrogen ions into more useful hydrogen gas.
The novelty of the device described by the researchers is the cheap materials and neutral conditions used in its construction. Prior to this study, incredibly expensive light absorbing materials were used, coupled with a highly acidic or basic medium.
"The exciting thing is [the] ability to make a functional device from Earth abundant materials, and to go someway to prevent the corrosion of those materials as they function," commented Rosalie Hocking, a chemist from Monash University in Melbourne who also studies artificial photosynthesis.
Mass applications expected
For both studies, the way forward involves further tweaking of the designs to make them applicable at industrial scales.
The water-splitting group also have plans to expand the design to one that does not require the standard flat panel setup. "Since there is no wiring, we could do this on nanoparticles too - a sort of artificial algae," said Nocera.
Masel was positive that the research into CO2 conversion could be scaled up to help contribute to carbon reduction schemes. "We hope to have large scale applications demonstrated by 2018, so they can start to be deployed to meet the 2020 carbon emissions goals."