A Layered Titanate Nanowire Helps Pt/TiO2 Photocatalyst for Solar Hydrogen Evolution from Water with High Quantum Efficiency

Abstract

Research into TiO2 photocatalysts for solar H2 evolution from water is still growing for environmentally benign and economically valid H2 production. Herein, in contrast to many researches on the modification of TiO2 toward higher photocatalytic activities, we develop a photocatalytically inactive TiO2-based nanostructure and use it, like graphene, as a booster of a benchmark TiO2. A layered potassium titanate with two-dimensional plate-like particle morphology was converted to the corresponding one-dimensional nanowire form via a hydrothermal reaction, after which the layered potassium titanate nanowire was acid-treated to obtain a layered titanate nanowire. This nanowire was completely inactive toward H2 evolution from water containing methanol under solar simulator irradiation. However, when Pt nanoparticle-loaded P25 TiO2 (Pt/P25) was mixed with a considerably smaller amount of the layered titanate nanowire in water, a durable composite was obtained and the composite showed a good photocatalytic activity three times higher than Pt/P25. The apparent quantum efficiency of the reaction at wavelength of 350 nm was 56%, which was higher than or comparable to those of the state-of-the-art TiO2-based photocatalysts. The possible reason for the enhanced photocatalytic activity of the Pt/P25 and layered titanate nanowire composite involved the transfer of photogenerated holes from Pt/P25 to the nanowire to suppress charge recombination and/or disaggregation (improved dispersion) of Pt/P25 particles on the nanowire.