XPS study of V1.67Ti0.33O5±δ·nH2O xerogels intercalated with hydroquinone

Abstract

Layered nanocomposites of V_1.67Ti_0.33O_5±δ⋅nH₂O gels are synthesized by using sol-gel technology. Then an aqueous solution of hydroquinone (HQ) was mixed with the formed gel in molar ratio 0.33 : 1 and 0.17 : 1 respectively. In this way the V_1.67Ti_0.33O_5±δ⋅nH₂O/2HQ and V_1.67Ti_0.33O_5±δ⋅nH₂O/HQ gels were synthesized. The valences of vanadium and titanium ions in the investigated compounds are studied by means of X-ray photoelectron spectroscopy (XPS) before and after etching the samples with Ar⁺ ions for 15 min (3 keV, current density 10 μAcm^–2). XPS analysis results show that independent of the hydroquinone intercalation degree (one or two hydroquinone) and Ar⁺ ion etching the ions of titanium are in stable 4+ states. Vanadium ions in all cases (one or two hydroquinone, before and after etching) are in V³⁺, V⁴⁺, and V⁵⁺ states. The increase in quantity of hydroquinone in the samples leads to higher concentration of V³⁺ and V⁴⁺ ions. The concentrations of lower valence vanadium ions increase after Ar⁺ ion etching of the samples.
Keywords: vanadium hydrates, sol-gel technology, hydroquinone, XPS
PACS: 79.60.-i, 81.20.Fw, 82.70.Gg