Hopper-like framework growth evolution in a cubic system: a case study of Cu₂O

Hopper-like Cu₂O cubes were crystallized in alkaline citrate-copper solution by controlling the equilibrium between complexation, precipitation and redox reactions. This work opens a predictive way to rational crystallization of oxide micro/nanocrystals and links chemical reactions with the crystallization process, because OH^- ions are always involved in these chemical reactions.