TiO2 nanotubes with laterally spaced ordering enable optimized hierarchical structures with significantly enhanced photocatalytic H2 generation

摘要

In the present work we grow self-organized TiO2 nanotube arrays with adefined and controlled regular spacing between individual nanotubes. Thesedefined intertube gaps allow to build up hierarchical 1D-branched structures,conformally coated on the nanotube walls using a layer by layer nanoparticleTiO2 decoration of the individual tubes, i.e. having not only a high controlover the TiO2 nanotube host structure but also on the harvesting layers. Afteroptimizing the intertube spacing, we build host-guest arrays that show adrastically enhanced performance in photocatalytic H2 generation, compared toany arrangement of conventional TiO2 nanotubes or conventional TiO2nanoparticle layers. We show this beneficial effect to be due to a combinationof increased large surface area (mainly provided by the nanoparticle layers)with a fast transport of the harvested charge within the passivated 1Dnanotubes. We anticipate that this type of hierarchical structures based onTiO2 nanotubes with adjustable spacing will find even wider application, asthey provide an unprecedented controllable combination of surface area andcarrier transport.