Facile synthesis of cubic cuprous oxide for electrochemical reduction of carbon dioxide

High level of atmospheric carbon dioxide (CO 2 ) concentration is considered one of the main causes of global warming. Electrochemical conversion of CO 2 into valuable chemicals and fuels has promising potential to be implemented into practical and sustainable devices. In order to efficiently realize this strategy, one of the biggest efforts has been focused on the design of catalysts which are inexpensive, active and selective and can be produced through green and up-scalable routes. In this work, copper-based materials are simply synthesized via microwave-assisted process and carefully characterized by physical/chemical/electrochemical techniques. Nanoparticle with a cupric oxide (CuO) surface as well as various cuprous oxide (Cu 2 O) cubes with different sizes is obtained and used for the CO 2 reduction reaction. It is observed that the Cu 2 O-derived electrodes show enhanced activity and carbon monoxide (CO) selectivity compared to the CuO-derived one. Among various Cu 2 O catalysts, the one with the smallest cubes leads to the best CO selectivity of the electrode, attributed to a higher electrochemically active surface area. Under applied potentials, all Cu 2 O cubes undergo structural and morphological modification, even though the cubic shape is retained. The nanoclusters formed during the material evolution offer abundant and active reaction sites, leading to the high performance of the Cu 2 O-derived electrodes. Graphic abstract