The role of malachite nanorods for the electrochemical reduction of CO2 to C2 hydrocarbons

Abstract The electrochemical reduction of CO 2 to higher hydrocarbons is a very challenging process that has high potential for the storage of large amounts of renewable energy with a high gravimetric and volumetric energy density. The distribution of hydrocarbons from the electrocatalytic reduction of CO 2 is primarily determined by the interaction of the cathode material with the CO 2 in the electrolyte. While the research on the electrochemical CO 2 reduction focuses on the cathode metal and surface structure of the metals, recently evidence was found that the metal itself may not be the active species but rather the product formed from the metal and CO 2 . In this paper, we report about the synthesis, catalytic activity and selectivity of nanostructured metal carbonate, i.e. malachite, as a highly active catalyst for the electrochemical synthesis of C2 hydrocarbons. These first results obtained on Cu 2 (OH) 2 CO 3 nanorod-structured “trees” show that carbonate, not the pure metal, is the active catalytic species. This new catalyst favors the production of ethylene (C 2 H 4 ) and ethane (C 2 H 6 ) with significantly higher Faradaic efficiency than that of the pure Cu surface.