Black TiO2 nanotubes formed by high energy proton implantation show   noble-metal-co-catalyst free photocatalytic H2-evolution
  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. 
Ning Liu, Volker H\"aublein, Xuemei Zhou, Umamaheswari Venkatesan,   Martin Hartmann, Mirza Ma\v{c}kovi\'c, Tomohiko Nakajim...
physics.chem-ph