p-Nitrophenol (PNP) is a difficultly decomposed organic pollutant under solar light in the absence of strong oxidants. This study shows that under artificial solar light PNP can be effectively degraded by a Cu(2)O/TiO(2) p-n junction network which is fabricated by anodizing Cu(0) particles-loaded TiO(2) nanotubes (NTs). The network is composed of p-type Cu(2)O nanowires on the top surface and Cu(2)O nanoparticles on the inner walls of the n-type TiO(2) NT arrays. The Cu(2)O/TiO(2) network shows much higher degradation rate (1.97 μg/min cm(2)) than the unmodified TiO(2) NTs (0.85 μg/min cm(2)). The enhanced photocatalytic acitivity can be attributed to the extended absorption in the visible resulting from the Cu(2)O nanowire networks and the effective separation of photogenerated carriers driven by the photoinduced potential difference generated at the Cu(2)O/TiO(2) p-n junction interface.

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.

In this paper, ionic liquid (IL)-coated magnetic Fe(3)O(4) nanoparticles (NPs) as an adsorbent of mixed hemimicelles solid-phase extraction (SPE) was investigated for the preconcentration of polycyclic aromatic hydrocarbons (PAHs) from environmental samples. Due to the high surface area and excellent adsorption capacity of the Fe(3)O(4) NPs after modification with ILs, satisfactory extraction recoveries can be achieved with only 80 mg Fe(3)O(4) NPs, 50 mg IL, 300 mL solution at pH = 10 and 10 min for equilibration. A comprehensive study of the adsorption conditions such as the amount of Fe(3)O(4) NPs and ILs, the solution pH, ionic strength, standing time, breakthrough volume, and desorption solvents was presented. The extraction ability of different coating agents, such as 1-hexadecyl-3-methylimidazolium bromide (C(16)mimBr), 1-decyl-3-methylimidazolium bromide (C(10)mimBr) and cationic surfactant cetyltrimethylammonium bromide (CTAB) was also compared. Under the optimized conditions, the recoveries for the water samples analysis were between 76 and 105% with relative standard deviations (RSDs) ranging from 3.9 to 6.9%, and the recoveries for soil samples were between 73 and 104% with RSDs ranging from 1.0 to 6.3%. In this method, only a small amount of C(16)mimBr (50 mg) and Fe(3)O(4) NPs (80 mg) was needed to obtain satisfactory recoveries.

Fabrication, properties, and sensing applications of TiO 2 nanotubes have been reviewed, and the highly ordered TiO 2 nanotube arrays made by anodic oxidation in fluoride-contained electrolytes highlighted. The effect of anodization parameters (electrolyte, pH, and voltage) on the titania nanotube size and shape were discussed. The excellent biocompatibility of TiO 2 , the high orientation, the large surface area with tunable pore sizes, as well as the high electron transfer rate along with the nanotubes make TiO 2 nanotube array an ideal substrate for the sensor's fabrication and application. The sensors based on the TiO 2 nanotube arrays for sensing hydrogen, oxygen, humidity, glucose and hydrogen peroxide all exhibited low detection limit, high stability, very good reproducibility and high sensitivity. anodization, TiO 2 nanotube arrays, sensor Citation:Yang L X, Luo S L, Cai Q Y, et al. A review on TiO 2 nanotube arrays: Fabrication, properties, and sensing applications.Nanostructural titania is one of the most widely studied materials due to its unique and excellent properties in optics, electronics, photochemistry and biology, as well as its applications in photovoltaic cells, photocatalysis, and sensors [1-3]. Among the various forms of nanostructural titania, nanotubular titania has attracted increasing interest due to its highly ordered structure and the convenient controlling of the size. Reviews have been given on the fabrication, properties, and applications of titania nanotubes in solar cells [4−6]. It is known that the sensors are increasingly demanded in medicinal, industrial, environmental applications. Sufficient sensitivity, high stability, short response time and long length of life are all key factors for a sensor's application in practice. Generally, the performance of the chemical sensors is optimized by improving the electric properties of the sensor through modifying or selecting more ideal substrates with excellent morphology. With the advent of nanotechnology, it has become evident that nanoscale architectural features of the functional materials applied in sensing can yield superior and unexpected electric behaviors. Recently, TiO 2 nanotube arrays fabricated by anodization were applied in the fabrication of gas sensors and biosensors [3]. The highly uniform morphology, unique orientated growing property, and large surface area with controllable pore sizes as well as the facile fabrication make the titania nanotube array a promising functional material for application in sensors. Furthermore, the photovoltaic property of TiO 2 under UV illumination makes the sensors self-clean the contamination, resulting in a long length of life. Consequently, in this review we focus on the recent developments in the fabrication, modification, and sensing application of the anodized titania nanotubes, which would open up new avenues for the development of sensors.