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SiC and graphene allow carbon capture with sunlight

Technology News |
By Nick Flaherty

Silcion carbide is turning out to be a promising material for low cost carbon capture systems that is powered by sunlight.

A team at Linköping University used cubic SiC with layers of graphene to build a photoelectrode around a Schottky junction that uses sunlight to convert CO2 into fuel such as methane when paired with a copper cathode. This fuel can then be used for a fuel cell in a hydrogen electric vehicle.

“By converting carbon dioxide to fuel with the aid of solar energy, this technique could contribute to the development of sources of renewable energy and reduce the impact on the climate of the combustion of fossil fuels,” said researcher Jianwu Sun, senior lecturer in the Department of Physics, Chemistry and Biology at Linköping University.

The article: “Atomic-Scale Tuning of Graphene/Cubic SiC Schottky Junction for Stable Low-Bias Photoelectrochemical Solar-to-Fuel Conversion” was published in ACS Nano

Graphene alone is not suitable for the solar energy conversion needed by the LiU researchers, so they combined it with transparent cubic silicon carbide (3C-SiC) in a process developed at the university. When the silicon carbide is heated, the silicon is vaporised and the carbon atoms remain and re-construct in the form of a graphene layer. The researchers have previously shown that it is possible to place up to four layers of graphene on top of each other in a controlled manner.

Combining the graphene and cubic silicon carbide produces a photoelectrode that preserves the ability of cubic silicon carbide to capture the energy of sunlight and create charge carriers. The graphene functions as a conducting transparent layer while protecting the silicon carbide in the carbon capture system.

The performance of the graphene-based technique is controlled by several factors, an important one of which is the quality of the interface between the graphene and the semiconductor. The team show they can tailor the layers of graphene on the silicon carbide and control the properties of the graphene-based photoelectrode to make the conversion of carbon dioxide more efficient.

The photoelectrode developed by the researchers can be combined with cathodes of various metals to select different chemical compounds. Methane for a fuel cell of a hydrogen vehicle would be produced with a copper cathode, carbon monoxide with a zinc cathode, or formic acid using bismuth.

“Most importantly, we have demonstrated that we can use solar energy to control the conversion of carbon dioxide to methane, carbon monoxide or formic acid,” said Sun.

www.liu.se

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