Facile synthesis and shape evolution of highly symmetric 26-facet polyhedral microcrystals of Cu₂O

A novel type of high symmetric 26-facet polyhedral microcrystals of Cu ₂O with well-developed {100}, {110}, {111} crystallographic faces are successfully synthesized in a properly selected reaction medium. These polyhedra exhibit a core-shell structure. An aqueous solution containing CuCl₂·2H₂O, sodium citrate (C₆H ₅Na₃O₇·2H₂O) complexing agent, glucose reductant, sodium dodecyl sulfate (SDS) surfactant, NaOH, and ethylene glycol (EG) constitutes the functional medium. By altering the EG to the water volume ratio, polyhedral, quasi-cubic, octahedral microcrystals are obtained directly. SDS, EG and C₆H₅Na₃O ₇·2H₂O have been confirmed to be the necessary additives to the development of different crystallographic planes. A possible growth mechanism involving aggregation of seed particles, oriented attachment, ripening process and surface reconstruction is proposed on the grounds of time-dependent experiments. The photocatalytic properties of the polyhedral microcrystals are also investigated.