A fast synthesis of hierarchical yolk–shell copper hydroxysulfates at room temperature with adjustable sizes

Hierarchical 3D yolk–shell copper hydroxysulfate microspheres were successfully synthesized by a fast synthesis method at room temperature. Both the core and the shell of the yolk–shell microspheres were assembled from 2D nanoplates or tiny nanoplatelets. The as-synthesized products were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS), atomic absorption spectrophotometry (AAS) and thermogravimetric analysis (TG). The diameter of the yolk–shell microspheres can be tuned by simply adjusting the concentration of the chelating agent, 1,3-propanediamine. This reaction can be scaled up by a factor of 1000 with almost no loss in yield. An Ostwald ripening controlled formation mechanism was proposed. Furthermore, the yolk–shell copper hydroxysulfates were evaluated as catalysts for the oxidation of styrene to benzaldehyde.