Efficient CO Oxidation by 50-Facet Cu₂O Nanocrystals Coated with CuO Nanoparticles

As carbon monoxide oxidation is widely used for various chemical processes (such as methanol synthesis and water-gas shift reactions H 2 O + CO ⇄ CO 2 + H 2 ) as well as in industry, it is essential to develop highly energy efficient, inexpensive, and eco-friendly catalysts for CO oxidation. Here we report green synthesis of ∼10 nm sized CuO nanoparticles (NPs) aggregated on ∼400 nm sized 50-facet Cu 2 O polyhedral nanocrystals. This CuO-NPs/50-facet Cu 2 O shows remarkable CO oxidation reactivity with very high specific CO oxidation activity (4.5 μmol CO m –2 s –1 at 130 °C) and near-complete 99.5% CO conversion efficiency at ∼175 °C. This outstanding catalytic performance by CuO NPs over the pristine multifaceted Cu 2 O nanocrystals is attributed to the surface oxygen defects present in CuO NPs which facilitate binding of CO and O 2 on their surfaces. This new material opens up new possibilities of replacing the usage of expensive CO oxidation materials.