3D graphene promises cheaper solar cells

A team from Michigan Technological University replaced the expensive platinum counter electrode in a dye sensitised solar cell with one made of 3d honeycomb graphene, before putting it into direct sunlight to measure its output. They found that 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 platinum (8%). To create the new structure, the researchers took graphene – a 2d form of carbon – and combined it with lithium oxide with carbon monoxide. This formed lithium carbonate (Li2CO3) and the honeycomb graphene. According to lead researcher Yun Hang Hu, the Li2CO3 helps to shape the graphene sheets and isolate 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. "Synthesising the 3d honeycomb graphene is neither expensive nor difficult," Hu noted, "and making it into a counter electrode posed no special challenges."