Arrays of copper oxide nanowires can convert CO2 to methanol with high efficiency in a solar-powered electrochemical device, according to researchers at the University of Texas, Arlington (Chem. Commun., DOI: 10.1039/c2cc38068d). The study may lead to methods that use low-cost, Earth-abundant materials to transform CO2, a greenhouse gas, to valuable products. Texas chemists Ghazaleh Ghadimkhani, Norma Tacconi, Krishnan Rajeshwar, and coworkers used a thermal process to grow CuO nanorods and an electrodeposition method to coat the rods with crystallites of a related oxide, Cu2O. The team selected the copper oxides because of their complementary electronic properties, broad solar absorption spectra, and high electrocatalytic activity. They fashioned electrodes from the nanorods, immersed the electrodes in CO2-rich aqueous solutions, and irradiated the solutions with simulated sunlight to generate a photocurrent. Tests show that the setup quickly generates methanol with 95% electrochemical (photoelectron-transfer) efficiency. In addition, the reaction runs without the overpotential (excess energy input) required by other electrochemical systems that convert CO2 to methanol.