Complete reduction of carbon dioxide to carbon using cation-excess magnetite

THE reduction of gaseous oxides such as CO 2 and H 2 O is an important concern in industrial processes and pollution control. Here we report the reduction of carbon dioxide to carbon with an efficiency of nearly 100% at 290 °C using cation-excess magnetite (Fe 3+δ O 4 , δ =0.127). In this reaction, the oxygen in the CO 2 is transferred, in the form of O 2− , to the cation-excess magnetite, and no gas is evolved. The carbon in the CO 2 is reduced to carbon (zero valence) by the addition of an electron donated from the cation-excess magnetite to maintain electrical neutrality during the transfer of the O 2− to the magnetite. When we used H 2 O in place of CO 2 , hydrogen gas was evolved, indicating that the same mechanism can also reduce H 2 O.