Enhanced photoelectrochemical performance of multi-leg TiO2 nanotubes through efficient light harvesting. (30th June 2015)

• Record Type: Journal Article
• Authors: Rambabu, Y; Jaiswal, Manu; Roy, Somnath C
• Is Part Of: Journal of physics. Volume 48:Number 29(2015)
• Publication Date: 2015-06-30
• Subjects: nanotubes -- photocurrent -- refractive index; Physics -- Periodicals; 530
• DOI: 10.1088/0022-3727/48/29/295302
• Languages: English
• ISSNs: 0022-3727

Abstract

Abstract: Multi-leg TiO2 nanotubes have been synthesised by electrochemical anodisation of Ti foils with suitable optimisation of the electrolyte (containing NH4 F and HF) composition and concentration. As a result, multi-leg nanotube morphology shows a 4-fold enhancement in photocurrent density compared with that of compact tubes of comparable length under UV-VIS (320–500 nm) light illumination. We attribute this enhancement in photocurrent to efficient light scattering within the multi-leg morphology and the availability of a large contact area with the electrolyte compared to that of compact nanotubes. A model has been presented for light trapping and scattering ability on the basis of the graded refractive index behaviour associated with multi-leg nanotubes. Such graded refractive index behaviour is found to reduce specular reflectance, leading to a greater scattering of light into the nanotube structure. The diffused reflectance spectra confirm higher scattering in the multi-leg nanotube arrays, which indicates greater light harvesting by the multi-leg nanotube arrays.