Spherically aggregated Cu2O–TA hybrid sub-microparticles with modulated size and improved chemical stability

Abstract

In this paper, tannic acid (TA) was used to assist the fabrication of spherically aggregated Cu₂O–TA hybrid sub-microparticles with good chemical stability and controllable sizes. TA exhibited multiple functions in the synthesis: the reductant for the formation of Cu₂O crystal seeds, the stabilizer of the primary Cu₂O crystals and the protector against the oxidation of Cu₂O. A probable mechanism was presumed, including 1) seed formation and TA encapsulation, 2) primary crystal nucleation and growth, and 3) aggregation into spheres. We found that pH played a key role in determining the final morphology of the product while the precursor concentration strongly influenced the size of the particles. At a suitable pH, hierarchically structured Cu₂O–TA sub-microspheres with nanocrystals as building blocks were produced. The size of the spheres can be tuned from 130 to 670 nm by adjusting the precursor concentration. Cu₂O–TA hybrids exhibited excellent chemical stability against water and oxygen. The method reported here possessed many advantages like cost-effectiveness, facility of preparation, environmental friendliness, chemical stability and excellent adjustability. The properties of the prepared Cu₂O particles might facilitate their applications in marine antifouling paints, adsorption materials and antibacterial agents.