Precise Control of Photoinduced Electron Transfer in Alternate Layered Nanostructures of Titanium Oxide–Tungsten Oxide

Abstract

The alternate layered structure was synthesized by the thiol–ene click reaction between the alkylthiol-modified tungsten oxide layer and the alkene-modified titanium oxide layer. The interlayer distances between the titanium oxide layer and the tungsten oxide layer were controlled to 0.72, 0.94, 1.01, and 1.14 nm by changing the carbon number of the functional groups. Photoinduced electron transfer from the titanium oxide layer to the tungsten oxide layer depends on the interlayer distance of the titanium oxide–tungsten oxide alternate layers from 0.7 to 1.1 nm. The alternate layers of narrow interlayer distance showed high photocatalytic activity in decomposition of methylene blue. The amount of the photoexcited electron transfer from titanium oxides to tungsten oxides was quantitatively measured by the reduction of Ag ions with the electrons stored in tungsten oxide. Because the rate of photoinduced electron transfer should be proportional to the amount of electron transfer, the tunneling decay constant β was estimated to be 0.63 Å–1 in the alternate layer samples, indicating that electrons transfer from titanium oxide to tungsten oxide by through-space tunneling.