Pt-Decorated g-C₃N₄/TiO₂ Nanotube Arrays with Enhanced Visible-Light Photocatalytic Activity for H₂ 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 C₃N₄ (g-C₃N₄) via a facile chemical vapor deposition approach. In comparison with classical TiO₂ nanotubes (anatase), the g-C₃N₄/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-C₃N₄-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-C₃N₄-combined 3 D nanoporous/nanotubular structure thus provides a platform with significant visible-light response in photocatalytic applications.