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

Titanium oxide and platinum have been intercalated into H2Ti4O9 and H4Nb6O17 by the successive reactions of H2Ti4O9 and H4Nb6O17 with [Pt(NH3)(4)]Cl-2, 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 x 10(9) and 0.12 x 10(9) s(-1), respectively, by measuring the TiO2 emission lifetimes in TiO2 incorporated nanocomposites. H-2,Ti4O9/(TiO2,Pt) and H4Nb6O17/TiO2,Pt) nanocomposites (intercalated with both TiO2 and Pt) were capable 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.