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]Cl2, >i-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 109 and 0. 12 x 109 s"1, respectively, by measuring the TiO2 emission lifetimes in TiO2 incorporated nanocomposites. H2Ti4O9/(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, H4Nb6Oi?/Pt and unsupported TiO2/Pt. The hydrogen and oxygen evolution was linear with time and the niobate system was fairly efficient.