Photochemical carbon dioxide reduction harnesses solar energy to convert CO
2 into higher-energy products. The chemical conversion of CO
2 already occurs on an industrial scale in the manufacture of solvents such as
formic acid, but photochemical reduction differs in that it relies on a renewable energy source, the sun. Because CO
2 is a
greenhouse gas, there is environmental interest in producing artificial systems that are efficient photocatalysts, but the low turn-over rates of current methods have prohibited wide-scale industrial application.