Synthesis and characterization of highly ordered TiO2 nanotube arrays for hydrogen generation via water splitting

Highly ordered TiO2 nanotube arrays (TNA) have been synthesized by anodization of Ti foils using an established electrochemical process. The parameters such as anodization potentials and durations have been varied to fabricate the specific morphology of TNA. In addition, Pt nanoparticles were deposited on these TNA via microwave irradiation. The photocurrent density–voltage (J–V) properties induced by the standard AM 1.5 solar simulator have been characterized using a potentiostat meter. The efficiency of photoelectrocatalytic effect of the large-pore-sized TNA (=120 nm) is found to be higher than those of the TNA in smaller pore sizes (≤100 nm). TNA with smaller pore sizes exhibit lower surface areas, and therefore, inferior photo-current efficiency to those of TNA with larger pore sizes. The low surface area of smaller-pore-sized TNA was resulted from the shorter tube length obtained at smaller anodizing voltages. Deposition of Pt nanoparticles on TNA was successfully accomplished using microwave irradiation technique. An enhanced hydrogen generation rate of 0.613 ml h−1 cm−2 (≅25.0 μmol h−1 cm−2) was obtained on these Pt-deposited TNA compared to the 0.313 ml h−1 cm−2 (≅12.8 μmol h−1 cm−2) of pristine TNA in a solution of methanol and water (1:1 ratio).