Pt-Decorated g-C 3 N 4 /TiO 2 Nanotube Arrays with Enhanced Visible-Light Photocatalytic Activity for H 2 Evolution.

Aligned TiO2 nanotube layers (TiNTs) grown by self-organizing anodization of a Ti-substrate in a fluoride-based electrolyte were decorated with graphitic-phase C3 N4 (g-C3 N4 ) via a facile chemical vapor deposition approach. In comparison with classical TiO2 nanotubes (anatase), the g-C3 N4 /TiNTs show an onset of the photocurrent at 2.4 eV (vs. 3.2 eV for anatase) with a considerably high photocurrent magnitude in the visible range. After further decoration with Pt nanoparticles, we obtained a visible-light responsive platform that showed, compared with g-C3 N4 -free TiNTs, a strong enhancement for photoelectrochemical and bias-free H2 evolution (15.62 μLh-1  cm-2 ), which was almost a 98-fold increase in the H2 production rate of TiNTs (0.16 μLh-1  cm-2 ). In a wider context, the g-C3 N4 -combined 3 D nanoporous/nanotubular structure thus provides a platform with significant visible-light response in photocatalytic applications.