Engineering highly active TiO2 photocatalysts via the surface-phase junction strategy employing a titanate nanotube precursor

TiO2 photocatalysts were synthesized by the hydrothermal treatment of titanate nanotube precursor at different HNO3 concentrations. Their structures were characterized, and their photocatalytic activity in H2 production from water was evaluated. The phase structure of TiO2 photocatalysts is dependent on the HNO3 concentration employed during the hydrothermal treatment and varies from pure anatase to pure rutile with increasing HNO3 concentration, with the heterophase in-between. The heterophase TiO2 photocatalysts exhibit large specific surface areas and intimately contacting anatase–brookite and anatase–rutile surface junctions. The presence of anatase–brookite and anatase–rutile-phase junctions on heterophase TiO2 photocatalysts was found to efficiently suppress recombination of photoinduced charge carriers in TiO2. The heterophase TiO2 photocatalysts are photocatalytically active in H2 production from water. TiO2 photocatalysts consisting of 72.9 wt% anatase, 24.6 wt% brookite, and 2.5 wt% rutile exhibits a photocatalytic H2 yield of 179 μmol h−1 g−1 under Xe lamp irradiation, about four times that of P25 (45.3 μmol h−1 g−1) under the same reaction conditions. These results demonstrate that the surface-phase junction strategy is very useful for engineering highly active TiO2 photocatalysts, and there still exists plenty of space to explore.