H2 Mapping on Pt-loaded TiO2 Nanotube Gradient Arrays
  We describe a rapid screening technique for determining the optimal characteristics of nano- photocatalysts for the production of H2 on a single surface. Arrays of TiO2 nanotubes (NTs) with a gradient in length and diameter were fabricated by bipolar anodization and a perpendicular gradient of Pt nanoparticles (NPs) was generated by the toposelective decoration of the TiO2 NTs. Photocatalytic hydrogen evolution was locally triggered with a UV laser beam and the arrays were screened in x- and y-direction for spatially resolved kinetic measurements and the mapping of the optimal hydrogen production. By using this technique, we demonstrate the time-efficient and straightforward determination of the tube dimensions and the Pt amount for an optimized H2 production. The concept holds promise to generally improve the study of many photoreactions as a function of the physicochemical characteristic of nano-photocatalysts, which renders it highly attractive for the optimization of various important chemical processes. 
G. Loget, P. Schmuki
cond-mat.mtrl-sci