Synthesis and Enhanced Photocatalytic Activity of Regularly Shaped Cu₂O Nanowire Polyhedra

A series of unique nanowire superstructures, Cu₂O nanowire polyhedra, have been synthesized through a cost-effective hydrothermal route. Three types of nanowire polyhedra, namely octahedra, concave octahedra, and hexapods, were formed in high morphological yields (90%) by reducing cupric acetate with o-anisidine or o-phenetidine in the presence of carboxylic acids. The architectures of these Cu₂O nanowire polyhedra were examined by electron microscopy, which revealed ordered, highly aligned Cu₂O nanowires within the polyhedral outlines. The growth of the Cu₂O nanowire polyhedra is controlled by the orientation and growth rates of the nanowire branches which are adjusted by addition of carboxylic acids. Compared to the Cu₂O samples reported in the recent literature, the Cu₂O nanowire octahedra exhibit notably enhanced photocatalytic activities for dye degradation in the presence of H₂O₂ under visible light, probably due to the high-density charge carriers photoexcited from the branched nanowires with their special structures. Additionally, the discussion in the recent literature of the photocatalytic activity of Cu₂O in the absence of H₂O₂ for direct photodegradation of dyes seems questionable.