Hierarchical zinc-copper oxide hollow microspheres as active Rochow reaction catalysts: The formation and effect of charge transferable interfaces

In this work, we report the preparation of nearly monodispersed and hierarchical CuxZnOy (6 < x < 100) hollow microspheres as catalysts for the Rochow reaction. The composites were synthesized by a facile one-pot and template-free hydrothermal method, which showed intergrowth and coexistence of the two components throughout the whole structure. The high-resolution transmission electron microscope (HRTEM) analysis confirmed the formation of intimate hetero-interfaces between CuO and ZnO in these composites. X-ray photoelectron spectroscopy (XPS), H2-temperature programmed reduction (H2-TPR) and Raman spectra results revealed the presence of a strong interaction between the two oxide components. The inclusion of Zn into the system increased electron density of Cu cores, leaving substantial holes on the surface of ZnO, thus forming the charge transferable channels between the two phases. These well-defined CuxZnOy samples were further utilized as model catalysts to investigate the relationship between structure modulation and catalytic performance. It was observed that the catalytic property can be easily tuned upon a systematic composition variation. Among CuO and various CuxZnOy samples, Cu10ZnOy exhibited the highest dimethyldichlorosilane (M2) selectivity and Si conversion in the Rochow reaction, mainly due to the formation of effective charge transfer interfaces as a result of intergrowth and coexistence effect.