3D graphene for solar power

Michigan Technological University scientists have developed 3D graphene, an inexpensive material that could replace the platinum in solar cells without degrading their efficiency.

Regular graphene is a famously two-dimensional form of carbon just a molecule or so thick. Hu and his team invented a novel approach to synthesise 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-sensitised 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%).

Synthesising the 3D honeycomb graphene is neither expensive nor difficult, said Hu, and making it into a counter electrode posed no special challenges.

The research has been funded by the American Chemical Society Petroleum Research Fund (PRF-51799-ND10) and the National Science Foundation (NSF-CBET-0931587). The article describing the work, ‘3D Honeycomb-Like Structured Graphene and Its High Efficiency as a Counter-Electrode Catalyst for Dye-Sensitized Solar Cells’, co-authored by Hu, Michigan Tech graduate student Hui Wang, Franklin Tao of the University of Notre Dame, Dario J Stacchiola of Brookhaven National Laboratory and Kai Sun of the University of Michigan, was published online 29 July in the journal Angewandte Chemie, International Edition.