Modified TiO₂ nanomaterials are considered to be promising in energy conversion and ferrites modification may be one of the most efficient modifications. In this research, various ferrites, incorporated with various cations (MFe₂O₄, M = Ni, Co, Zn and Sr), are utilized to modify the well aligned TiO₂ nanorod arrays (NRAs), which is synthesized by hydrothermal method. It is found that all MFe₂O₄/TiO₂ NRAs show obvious red shift into the visible light region compared with the TiO₂ NRAs. In particular, NiFe₂O₄ modification is demonstrated to be the best way to enhance the photoelectrochemical and photocatalytic activity of TiO₂ NRAs. Furthermore, the separation and transfer of charge carriers after MFe₂O₄ modification are clarified by electrochemical impedance spectroscopy measurements. Finally, the underlying mechanism accounting for the enhanced photocatalytic activity of MFe₂O₄/TiO₂ NRAs is proposed. Through comparison among different transition metals modified TiO₂ with the same synthesis process and under the same evaluating condition, this work may provide new insight in designing modified TiO₂ nanomaterials as visible light active photocatalysts.

In this paper, we propose a nanostructure with Au nanoparticles (NPs), as electron sinks, located at the most outside layer of CdS sensitized TiO₂ nanorod arrays (TiO₂ NRAs/CdS/Au). By the introduction of Au NPs, TiO₂ NRAs/CdS/Au performs higher visible light photocatalytic capacity in the degradation of unsymmetrical dimethylhydrazine wastewater than TiO₂ NRAs/CdS. The optimal deposition time for Au NPs is 30 s. The visible light induced degradation ability of TiO₂ NRAs/CdS/Au (30 s) is 1.4 times that of TiO₂ NRAs/CdS. The cycling stability of TiO₂ NRAs/CdS is greatly enchanced after Au NPs decoration, which can maintain 95.86% after three cycles. Photoluminescence spectra and photoelectrochemical measurements were carried out to reveal the underlying mechanism for the improved visible light photocatalytic capacity of TiO₂ NRAs/CdS/Au. This work demonstrates a promising way for the rational design of metal-semiconductor photocatalysts used in decomposition reaction that can achieve high photocatalytic efficiency.

The photoelectrochemical and photocatalytic properties of TiO ₂ nanorod arrays annealed in the air were investigated.

Photocatalysts with a superior activity range, from ultraviolet (UV) to near-infrared (NIR) light, are attractive for solar utilization. From this perspective, sulfides are promising due to their narrower bandgap than oxides. In this report, NaBiS₂ was synthesized hydrothermally under mild conditions by adjusting the alkaline amount. The rough NaBiS₂ nanosheets possessed various surface atomic configurations on their surfaces, including amorphous clusters and amorphous nano-domains, revealed by HRTEM. A theoretical investigation of the band structure employing the density functional theory (DFT) method for the first time indicated that NaBiS₂ is an indirect bandgap semiconductor with a narrow bandgap of 1.02 eV. Experimentally, it showed excellent photocatalytic activity for the degradation of methyl blue under UV, visible light and NIR light due to its experimental bandgap width of 1.32 eV. A degradation rate of 99.6% was reached after 80 min under full spectrum irradiation.

Photocatalysis technology could utilize solar energy to degrade many toxic pollutants and provides possibility to deal with unsymmetrical dimethylhydrazine (UDMH) wastewater with less energy consumption. In this study, well-aligned TiO2 nanorod arrays (TiO2 NRAs) were grown directly on transparent conductive glass (FTO) via a hydrothermal method, and TiO2 NRAs/CdS heterostructure films were prepared by decorating TiO2 NRAs with CdS nanoparticles through successive ion layer adsorption and reaction (SILAR). Under visible light, the TiO2 NRAs/CdS heterostructure displays enhanced photodegrading capacity compared with the bare TiO2 NRAs, and the highest photodegradation rate, 27.5% higher than that of the bare TiO2 NRAs, was achieved by the sample with 15 SILAR cycles. Additionally, the solution pH had some influence on the degradation process, which shows that the best degradation rate can be achieved in the neutral solution (pH is ca. 7.2), and the photodegradation process can be better in alkaline solution than in the acid solution. Moreover, the visible photocatalytic stability of the TiO2 NRAs/CdS sample was investigated. Finally, the underlying photocatalytic mechanism was discussed according to the photoelectrochemical and photoluminescence results.