Synthesis of self-aligned and vertically oriented carbon incorporated titania nanotube for improved photoelectrochemical hydrogen generation

Abstract

Photoelectrochemical splitting of water for chemical fuel production utilizing solar energy is regarded as an effective strategy to resolve crisis of energy. Self assembled and highly ordered titanium dioxide nanotube arrays offers considerable interest for hydrogen generation, since ordered structural design of titania nanotubes provides a unidirectional charge transfer channel for electron's transport. Here, we report the hydrogen generation by self assembled and vertically oriented carbon doped titania nanotube array. Carbon doped titania nanotube array photoelectrodes were synthesized by electrochemical method through the anodization of Titanium (Ti) foil in ethylene glycol bath consisting of 0.3 wt.% NH4F and 2 vol.% water by varying the anodization potential and time. The increase in length of carbon doped titania nanotube array increases the efficiency of photo conversion. However very higher lengths of carbon doped titania nanotube array results into decrease in the efficiency mainly due to recombination of charge carriers. The photocurrent density and hydrogen generation rate was found to be 4.0 mAcm−2 and 150 μmol cm−2 h−1 for carbon doped titania nanotube array of lengths 13.5 μm in 1 M NaOH electrolyte solution under 1.5AM solar irradiance of white light with illumination intensity of 100 mWcm−2.