TiO₂Nanotube Arrays Modified with Bi Nanoparticles for Enhancing Photoelectrochemical Oxidation of Organics

Abstract

Well aligned TiO2 nanotube arrays are used as photoelectrochemical sensor for organic compounds detection due to their excellent photocatalytic performance. The high background photocurrent and low current response to trace addition of organics restrain the detection performance of the photoelectrochemical sensor. Deposition of Bi nanoparticles onto the nanotube arrays by photocatalytic reduction of Bi3+ ions is found to decrease the background photocurrent and increase the current response effectively at the same time. Scanning electron microscope, high resolution transmission electronmicroscope and X-ray photoelectron spectrometer are used to characterize the structure, morphology and component of the Bi/TiO2 nanotube arrays. The concentration of Bi3+ ions and deposition parameters are optimized to achieve the best detecting performance. When glucose is used as target organics, the photoelectrochemical sensor can achieve a sensitivity of 0.3 μA/μM with a linear range of 0 to 1500 μM. The detection limit is calculated by triple signal noise ratio to be 4.5 μM. The mechanism of enhancing oxidation of organics is ascribed to the electrons transfer and the surface electrochemical reactions during the photoelectrochemical process.