Boosted photocatalytic hydrogen evolution by tuning inner pore size and co-catalyst thickness of the anodic TiO2 nanotubes

Abstract The formation of well aligned TiO 2 nanotubes with suitable inner diameters is a pre-requisite for photocatalytic application. The inner diameters can be tuned by the composition of electrolyte, anodization temperature, and applied potential. Here, we have successfully formed the TiO 2 nanotubes with wide inner diameters by controlling the anodization potential of the Ti metal substrate. The anodizations were performed in the aqueous solution of ethylene glycol mixed with hydrofluoric acid as an electrolyte at potentials of 150–240 V at 40 ℃. It resulted into TiO 2 nanotubes with inner diameters in the range of 160–400 nm and lengths about 6–8 μm, respectively. Moreover, the TiO 2 nanotubes were sputter coated with thin layers (1–5 nm) of Pt and Au nanoparticles. Finally, we compared the photocatalytic behavior of the as-prepared TiO 2 nanotubes and those coated with Au and Pt nanoparticles. Interestingly, 1 nm Pt coated 300 and 400 nm inner diameter TiO 2 nanotubes showed highest H 2 production rate of 25 μL h −1  cm -2 under a 10 h of light illumination.