Structure and electrochemical properties of species formed as a result of Cu(II) ion adsorption onto TiO{sub 2} nanoparticles
- Belarusian State Univ., Minsk (Belarus). Inst. of Physico-Chemical Problems
- Moscow State Univ. (Russian Federation). Dept. of Chemistry
- Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Chemical Physics
- Belarusian Academy of Sciences, Minsk (Belarus). Inst. of General and Inorganic Chemistry
- Univ. of Fribourg (Switzerland). Inst. of Inorganic Chemistry
Sol-gel-derived nanostructured TiO{sub 2} thin films and powders treated with Cu{sup 2+}-containing solutions have been studied using electrochemical methods, ESR, XPS, and electroreflection spectroscopies. Analysis of the voltammograms in combination with ESR data has allowed them to reveal at least four types of copper species formed on the TiO{sub 2} surface after the adsorption of aqueous Cu{sup 2+} ions. These are monovalent copper ions, magnetically isolated Cu(II) ions, Cu(II) ions forming specific areas (associates) with a high local concentration and strong interaction between the ions, and formally diamagnetic copper hydroxide species. The last type dominates when adsorbing Cu(II) ions from solutions with pH > 5 and its fraction increase with increasing the Cu{sup 2+} ion concentration in solution. The presence of Cu(I) ions at the TiO{sub 2} surface was proved independently by XPS measurements. The appearance of them can be associated with the partial reduction of adsorbed Cu{sup 2+} ions by electrons of the TiO{sub 2} matrix. The Cu(II) ions bound to the TiO{sub 2} surface give rise to the electroactive surface states within the band gap of the oxide. Their energy position has been determined by the electrolyte electroreflectance method. These surface states are located ca. 1.1 eV below the conduction band edge.
- OSTI ID:
- 347552
- Journal Information:
- Journal of Physical Chemistry B: Materials, Surfaces, Interfaces, amp Biophysical, Vol. 103, Issue 8; Other Information: PBD: 25 Feb 1999
- Country of Publication:
- United States
- Language:
- English
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