TiO2 nanotubes: N-ion implantation at low-dose provides noble-metal-free   photocatalytic H2-evolution activity
  Low-dose nitrogen implantation induces in TiO2 nanotubes a co-catalytic activity for photocatalytic H2-evolution. The use of an ion implantation process leads to a N-implanted zone only at the top part of the tubes. The coupling of this top layer and the underlying non-implanted part of the nanotubes strongly contributes to an efficient carrier separation and thus to a significantly enhanced H2 generation. 
Xuemei Zhou, Volker H\"aublein, Ning Liu, Nhat Truong Nguyen, Eva M.   Zolnhofer, Hiroaki Tsuchiya, Manuela S. Killian, Kars...
physics.chem-ph