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mercredi 21 août 2013

3-D Graphene — The Future Of Solar Cells?

3-D graphene can function as an effective — and very economical — substitute for the platinum that is commonly used in dye-sensitized solar cells, according to new research from Michigan Technological University. By substituting the newly created and relatively cheap material known as three-dimensional graphene for the very expensive and rare element of platinum the researchers think that the cost of dye-sensitized solar cells can be cut significantly.

Dye-sensitized solar cells (DSSCs) are a very promising type of solar cell that are easy to produce, flexible, and relatively efficient at converting solar energy into electricity. As they are currently produced, though, they rely on a number of relatively expensive materials, such as platinum — platinum currently sells for somewhere around $1500 an ounce, so if a cheaper material could be found to replace platinum then the total cost of producing DSSCs could no doubt be reduced significantly. That’s where 3-D graphene comes in. The newly created material can effectively replace platinum in DSSCs without diminishing their efficiency.

“A field emission scanning electron microscopy (FESEM) image of 3D honeycomb-structured graphene. The novel material can replace platinum in dye-sensitized solar cells with virtually no loss of generating capacity.” Image Credit: Hui Wang

The press release from Michigan Technological University provides details on the new material:

Regular graphene is a famously two-dimensional form of carbon just a molecule or so thick. Yun Hang Hu, the Charles and Caroll McArthur Professor of Materials Science and Engineering, and his team invented a novel approach to synthesize a unique 3D version with a honeycomb-like structure. To do so, they combined lithium oxide with carbon monoxide in a chemical reaction that forms lithium carbonate (Li2CO3) and the honeycomb graphene. The Li2CO3 helps shape the graphene sheets and isolates them from each other, preventing the formation of garden-variety graphite. Furthermore, the Li2CO3 particles can be easily removed from 3D honeycomb-structured graphene by an acid.

The researchers determined that the 3D honeycomb graphene had excellent conductivity and high catalytic activity, raising the possibility that it could be used for energy storage and conversion. So they replaced the platinum counter electrode in a dye-sensitized solar cell with one made of the 3D honeycomb graphene. Then they put the solar cell in the sunshine and measured its output. The cell with the 3D graphene counter electrode converted 7.8% of the sun’s energy into electricity, nearly as much as the conventional solar cell using costly platinum (8%).

The researchers note that the process of synthesizing the 3-D honeycomb graphene is relatively cheap and easy — there are no significant barriers to its wider adoption. As they put it: “Making it into a counter electrode posed no special challenges.”

The research has been funded by both the American Chemical Society Petroleum Research Fund and the National Science Foundation.

Published on August 21st, 2013 | by Nathan

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