Intercalation of titanium oxide in layered H₂Ti₄O₉ and H₄Nb₆O₁₇ and photocatalytic water cleavage with H₂Ti₄O₉/(TiO₂, Pt) and H₄Nb₆O₁₇/(TiO₂, Pt) nanocomposites

Abstract

Titanium oxide and platinum have been intercalated into H₂Ti₄O₉ and H₄Nb₆O₁₇ by the successive reactions of H₂Ti₄O₉ and H₄Nb₆O₁₇ with [Pt(NH₃)₄]Cl₂, n-C₃H₇NH₂ and acidic TiO₂ colloid solutions followed by UV light irradiation. The thicknesses of titanium oxide and platinum were less than 0.7 nm. The band gap energy of the titanium oxide incorporated was less than 3.4 eV. The rate constants for the charge injection from excited TiO₂ into the conduction band of H₂Ti₄O₉ and H₄Nb₆O₁₇ were determined to be 0.11×10⁹ and 0.12×10⁹ s^-1, respectively, by measuring the TiO₂ emission lifetimes in TiO₂ incorporatednanocomposites. H₂Ti₄O₉/(TiO₂, Pt) and H₄Nb₆O₁₇/(TiO₂ ,Pt) nanocomposites (intercalated with both TiO₂ and Pt) werecapable of water cleavage into hydrogen and oxygen without a hole scavenger, at 0.088–0.104 mmol h^-1, following irradiation from a 450 W Hg lamp, although no noticeable gas was evolved in the presence of H₂Ti₄O₉/TiO₂, H₄Nb₆O₁₇/TiO₂, H₂Ti₄O₉/Pt, H₄Nb₆O₁₇/Pt and unsupported TiO₂/Pt. The hydrogen and oxygen evolution was linear with time and the niobate system was fairly efficient.

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