Fabrication and Photoluminiscent Properties of Cylindrical and Conicalshaped Titania Nanotube Photoanodes and it's Application in Hydrogen Generation via Photoelectrochemical Process

Using anodic oxidation with a constant/time-dependent linearly varying anodization voltage, we have made films of cylindrical and conical-shaped titania nanotube arrays. X-ray diffraction indicates the amorphous nature of the films and annealing improves its crystalline nature. Diffuse reflectance spectra reveals the band gap of cylindrical and conical nanotubes as 3.05 and 2.8 eV respectively. Photoluminescence spectra recorded at two different excitation wavelengths reveal the existence of surface defect states. We collected the hydrogen gas for both the cylindrical andconical nanotube arrays in a 1 M KOH electrolyte with 10 vol% ethylene glycol illuminatedusing Xenon lamp.The hydrogen generation incylindrical and conical titaniananotube arrays at an illumination of 10 mW/cm2 for 1 h is 0.10 and 0.12 mL respectively.