In a new study, a team of scientists from the Korea Research Institute of Chemical Technology in Daejon, South Korea, and Ewha Womans University in Seoul, South Korea, have demonstrated that graphene may serve as an efficient photocatalyst for improving the efficiency of an artificial photosynthesis system. As a photocatlyst, graphene uses sunlight to spur the reaction without becoming involved itself. As the researchers explain, a good photocatalyst for such a system should operate in the visible light spectrum, since 46% of total sunlight energy on Earth is in the visible range and only 4% in the UV range. Previous studies have experimented with graphene-semiconductor composites as photocatalysts, but the results showed that these materials had low electron transfer levels, which led to low efficiencies. In the new study, the scientists used graphene by itself as the photocatalyst, which they then coupled to a porphyrin enzyme. The researchers demonstrated that this material could convert sunlight and carbon dioxide into formic acid, a chemical that is used in the plastic industry and as fuel in fuel cells. Tests showed that the graphene-based photocatalyst is highly functional in the visible light regime, and that its overall efficiency is significantly higher than the efficiencies of other photocatalysts.