Fossil fuel use, ranging from electricity generating power plants to automobiles, pumps billions of tons of greenhouse gases into the atmosphere annually, changing the climate in ways that are likely to be detrimental to future generations. The rising use of fossil fuels, driven by population growth and rising standards of living across the globe, adds to the urgency of finding a solution to the problem of rapidly increasing atmospheric carbon dioxide, the major greenhouse gas. At Penn State, a team of researchers led by Craig Grimes has come up with an ingenious method of turning captured CO2 into methane, a combustible fuel, using the energy of the sun. Writing in Nano Letters (Volume 9, 2009, pp 731-737), Grimes and his team describe a highly efficient photocatalyst that can yield significant amounts of methane, other hydrocarbons, and hydrogen in a simple, inexpensive process. The team used arrays of nitrogen-doped titania nanotubes sputter-coated with an ultrathin layer of a platinum and/or copper co-catalyst(s). The titania captures high energy ultraviolet wavelengths, while the copper shifts the bandgap into the visible wavelengths to better utilize the part of the solar spectrum where most of the energy lies. In addition, the thin-walled nanotubes increase […]