TPR, ESR, and XPS Study of Cu2+Ions in Sol–Gel-Derived TiO2

✍ Scribed by G. Córdoba; M. Viniegra; J.L.G. Fierro; J. Padilla; R. Arroyo

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 284 KB
• Volume: 138
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1997.7690

✦ Synopsis

Fine titanium(IV) oxide amorphous powders containing two different amounts of CuO were prepared by the sol-gel process. The samples were crystallized to anatase by heating. The reduction of CuO-TiO 2 samples was investigated by temperature-programmed reduction (TPR). Three types of signals were detected: Two of them are strong and were assigned to two different types of copper ions distributed on the surface. The third kind was a weak broad signal and was ascribed to the simultaneous reduction of titanium and a third type of copper ion incorporated into the TiO 2 network. This was confirmed by electron spin resonance measurements of the samples before and after programmed reductions at various temperatures selected from the TPR profiles. The results showed that the lowest reduction temperature is due to the existence of isolated copper ions distributed on the surface. The second TPR peak was due to a CuO phase with small particle size. These results were consistent with X-ray photoelectron spectroscopy studies, which showed two signals assigned to -Cu-O-Ti-O-and CuO species.