Enhanced Visible-Light-Induced Photoelectrocatalytic Degradation of Methyl Orange by CdS Sensitized TiO2 Nanotube Arrays Electrode

In this work, CdS sensitized TiO2 nanotube arrays （CdS/TiO2NTs） electrode was synthesized with the CdS deposition on the highly ordered titanium dioxide nanotube arrays （TiO2NTs） by sequential chemical bath deposition method （S-CBD）. The as-prepared CdS/TiO2NTs was characterized by field-emission scanning electron mi- croscopy （FE-SEM） and X-ray diffraction （XRD）. The results indicated that the CdS nanoparticles were effectively deposited on the surface of TiOeNTs. The amperometric I-t curve on the CdS/TiO2NTs electrode was also presented. It was found that the photocurrent density was enhanced significantly from 0.5 to 1.85 mA/cm2 upon illumination with applied potential of 0.5 V at the central wavelength of 253.7 nm. The photoelectrocatalytic （PEC） activity of the CdS/TiO2NTs electrode was investigated by degradation of methyl orange （MO） in aqueous solution. Compared with TiO2NTs electrode, the degradation efficiencies of CdS/TiO2NTs electrode increased from 78% to 99.2% under UV light in 2 h, and from 14% to 99.2% under visible light in 3 h, which was caused by effective separation of the electrons and holes due to the effect of CdS, hence inhibiting the recombination of electron/hole pairs of TiO2NTs.