Synthesis and characterization of Ta2O5/HfO2/carbon clusters composite materials

Nano-sized Ta2O5/HfO2/carbon clusters composite material has been successfully obtained by the microwave-irradiated calcination of a (EtO)4Ta(acac)/HfCl4/epoxy resin complex. The compositions of the resulting composite materials were determined using inductively coupled plasma (ICP) spectroscopy, elemental analysis and surface characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ultraviolet–visible (UV–vis), X-ray photoelectron spectra (XPS) and electron spin resonance (ESR) spectra of the composites were also measured. XPS spectral examinations suggest the possibility of a two-step electron transfer in the process of Ta2O5 → carbon clusters → HfO2 with an oxidation site at Ta2O5 particles and a reduction site at HfO2 particles. The reduction reaction of methylene blue with the calcined materials under the visible light irradiation has also been examined.