In-situ synthesis of amorphous H2TiO3-modified TiO2 and its improved photocatalytic H2-evolution performance.

Surface cocatalyst modification is considered as one of the most ideal strategies for improved photocatalytic H2-evolution activity of photocatalysts. It is quite important to develop new cocatalyst and to enhance the interfacial coupling between cocatalysts and photocatalysts with the aim of promoting the rapid transfer of photogenerated charge. In this work, amorphous H2TiO3 (a-H2TiO3) nanoparticles (ca. 1 nm), as a novel and effective hole cocatalyst, were homogeneously in-situ generated on TiO2 surface (the sample was referred as a-H2TiO3/TiO2) via a first controllable surface reaction of TiO2 in a NaOH solution and the following ion-exchange reaction with HCl solution at room temperature. The resultant a-H2TiO3/TiO2 photocatalysts exhibited greatly enhanced photocatalytic H2-evolution performance compared with pure TiO2, which was mainly attributed to amorphous H2TiO3 nanoparticles as hole cocatalysts for rapid hole transfer. To further promote the photocatalytic activity of a-H2TiO3/TiO2, Ni(OH)2 as electron cocatalysts was loaded on the surface of a-H2TiO3/TiO2 to prepare the co-modified a-H2TiO3/TiO2/Ni(OH)2 photocatalyst. The results indicated that the H2-evolution performance of the a-H2TiO3/TiO2/Ni(OH)2 photocatalyst was significantly higher than that of a-H2TiO3/TiO2 by a factor of 66.7 due to the synergy of a-H2TiO3 and Ni(OH)2 cocatalysts. This study provides a strategic approach for enhanced H2-evolution activity by enhanced interfacial coupling between cocatalysts and photocatalysts.