Twins in polyhedral 26-facet Cu7S4 cages: Synthesis, characterization and their enhancing photochemical activities

Abstract

Unusual polyhedral 26-facet Cu₇S₄ cages wholly exposed with amazingly unique nanotwinned structures as building blocks were successfully synthesized via a facile ethanol-assisted sacrificial Cu₂O templates approach. Furthermore, a solvent-controlled fabrication of polyhedral copper sulfides (Cu₇S₄ and CuS) with different stoichiometries and microstructures can be artificially achieved, which is determined by the intrinsic difference of the surface states of Cu₂O templates. Structural and morphological evolutions were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and field-emission scanning electron microscopy (FESEM). Stoichiometric-dependent characteristics were demonstrated in the UV–vis absorption investigations. The as-prepared Cu₇S₄ microcages exhibit higher photocatalytic activity for enhancing degradation of methylene blue, which might be attributed to their special nanotwinned building blocks. This study is of great importance in “bottom-up” assembly of unusual ordering hollow copper sulfides superstructures, but also offers a good opportunity to understand the fundamental significance of nanotwinned structures for their potential applications.