Facile fabrication of faceted copper nanocrystals with high catalytic activity for p-nitrophenol reduction

This article reports a reproducible and facile approach to synthesize faceted copper nanocrystals (Cu NCs) using an inexpensive copper oxide as a precursor. By simply prolonging the reaction time, Cu cubes and polyhedrons were successfully produced, and the mean size could be effectively controlled in the range of 9 to 21 nm. The catalytic activities of the Cu cubes and polyhedrons were investigated by photometrically monitoring the reduction of p-nitrophenol by an excess of NaBH4. The kinetics of the reduction reaction at different temperatures were investigated to determine the activation parameters. Our investigations indicate that Cu nanocubes exhibit higher catalytic activity than Cu polyhedrons, which can be ascribed to three features: the higher surface-to-volume ratio, the higher surface energy of the {100} facet, and the lower redox potential. In addition, these catalysts can be easily recycled with a slight decrease of the catalytic activities, and are stable in the air. Therefore, this facile route provides a useful platform for the fabrication of Cu catalysts which have the potential to replace noble metals for certain catalytic applications.