Surface reactivity of reduced titanium dioxide

Abstract

A moderate surface reduction of TiO₂(anatase or rutile) at 573–773 K under vacuum, or in the presence of carbon monoxide or hydrogen, or finally at room temperature under ultra-violet irradiation in vacuum or in the presence of hydrocarbons, creates two types of paramagnetic centres, which are identified by e.s.r. spectra as Ti³⁺ ions.

Adsorption of oxygen (between 77 and 373 K) on TiO₂ samples reduced in the ways described above leads to the formation of ionic species of the type O^–₂. The same species are also formed at room temperature on unreduced TiO₂ samples submitted to an UV irradiation in the range of 2000–6000 Å.

These results are paralleled with the occurrence of photocatalytic (in u.-v.) partial oxidation of isobutane on TiO₂ at room temperature.