Heterogeneous reaction between Li and anatase TiO2nanoparticles under ultra-high vacuum

Abstract

We demonstrate heterogeneous chemistry between Li and anatase TiO₂ nanoparticles under UHV. The reduction of TiO₂ upon formation of lithium oxide proceeds via two different schemes: one that reduces Ti⁴⁺ to Ti³⁺ and one that reduces Ti⁴⁺ directly to Ti²⁺. The second scheme sets in only after a critical degree of reduction (i.e. Li amount) has been reached (Li/Ti = 0.28) and is associated with restructuring of the film. Two films with different morphologies were compared and the results demonstrate that the reaction between Li and larger TiO₂ structures (30–50 nm) is kinetically restricted while such effects were significantly less prominent for small particles (10 nm).