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 H 2 Ti 4 O 9 and H 4 Nb 6 O 17 by the successive reactions of H 2 Ti 4 O 9 and H 4 Nb 6 O 17 with [Pt(NH 3 ) 4 ]Cl 2 , n-C 3 H 7 NH 2 and acidic TiO 2 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 TiO 2 into the conduction band of H 2 Ti 4 O 9 and H 4 Nb 6 O 17 were determined to be 0.11×10 9 and 0.12×10 9 s -1 , respectively, by measuring the TiO 2 emission lifetimes in TiO 2 incorporatednanocomposites. H 2 Ti 4 O 9 /(TiO 2 , Pt) and H 4 Nb 6 O 17 /(TiO 2 ,Pt) nanocomposites (intercalated with both TiO 2 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 H 2 Ti 4 O 9 /TiO 2 , H 4 Nb 6 O 17 /TiO 2 , H 2 Ti 4 O 9 /Pt, H 4 Nb 6 O 17 /Pt and unsupported TiO 2 /Pt. The hydrogen and oxygen evolution was linear with time and the niobate system was fairly efficient.