TiO(2) nanotube arrays (NTAs) are modified with PbS nanoparticles by successive ionic layer adsorption and reaction (SILAR) or electrodeposition, with an aim towards tuning the photoelectrochemical cell to the visible region. The PbS modification of the TiO(2) NTAs results in an increase in the visible light adsorption, however the increase in photocurrent is dependent on the modification method. PbS/TiO(2) NTAs prepared by SILAR and electrodeposition show, respectively, photocurrents of 11.02 and 5.72 mA/cm(2). The increase in photocurrent is attributed to enhanced charge separation efficiency and improved electron transport.

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CdSe nanoparticles with well dispersion were decorated on inner and outer surfaces of 4 μm long TiO2 nanotubes through a simple direct current electrotechnique, resulting in a composite functional material with a perfect construction. The applied depositing voltage plays a determinative role during the CdSe nanoparticles formation process, getting through the breakdown potential of TiO2 and providing intense active sites for the CdSe crystal growth on the TiO2 nanotubes. The CdSe/TiO2 composite nanotube arrays exhibit high absorption in the visible light region due to the narrow band gap of CdSe, and depict sensitive photoelectrochemical response under visible light illumination. Photocatalytic degradation of anthracene-9-carbonxylic acid (ACA), one of the derivants of persistent organic pollutants (POPs), was successfully achieved on CdSe/TiO2 nanotubes when exposed to the 550 nm green monochromatic light.

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Carbon nanotubes with high orientation and low graphitization formed in TiO2 nanotube arrays were fabricated by annealing the latter in carbon atmosphere, constructing a novel functional material with tube-in-tube nanostructure. Compared with unmodified TiO2, coupled C−TiO2 photocatalyst shows an enhanced efficiency of photodecomposing methyl orange process due to the increasing carrier rate and stronger adsorbability as well as the unique mechanical nanostructure. Furthermore, the transition from anatase to rutile was suppressed by carbon, resulting in a high content of the photoactive anatase, which also benefits the high catalytic activity of C−TiO2 photocatalyst.