Elucidating a twin-dependent chemical activity of hierarchical copper sulfide nanocages

Abstract

We have demonstrated significant evidence of a solvent-dependent synthesis of hierarchical Cu₇S₄ polycrystalline nanocage assemblies with controllable aggregation-based building blocks by a sacrificial Cu₂O template approach. The formation of a hierarchical Cu₇S₄ polycrystalline nanocage is essentially determined by a Kirkendall effect, which is attributed to the tailored-aggregation behaviour of the nanoscale building blocks during the replacement/etching process in different polarities of solvent. The hierarchical Cu₇S₄ polycrystalline nanocage assembly of nanoparticle building blocks was prepared in pure water, while the hierarchical Cu₇S₄ polycrystalline nanocage assembly of twinned nanoplate building blocks was successfully synthesized in an anhydrous ethanol capping environment. Such a hierarchical Cu₇S₄ polycrystalline nanocage assembly of twinned nanoplate building blocks exhibits a higher photocatalytic activity than that of the common polycrystalline ones. A nanotwin-dependent photochemical mechanism has been proposed. Significantly, this study is of great importance in bottom-up assembly of controllable ordered architectures, and offers a good opportunity to understand the fundamental importance of the formation mechanism and growth process of hierarchical Cu₇S₄ polycrystalline nanocages with controllable aggregation-based building blocks.