  We apply high-energy proton ion-implantation to modify TiO2 nanotubes
selectively at their tops. In the proton-implanted region we observe the
creation of intrinsic co-catalytic centers for photocatalytic H2-evolution. We
find proton implantation to induce specific defects and a characteristic
modification of the electronic properties not only in nanotubes but also on
anatase single crystal (001) surfaces. Nevertheless, for TiO2 nanotubes a
strong synergetic effect between implanted region (catalyst) and implant-free
tube segment (absorber) can be obtained.
