An innovative Z-type Sb2S3/In2S3/TiO2 heterostructure: superior performance in the photocatalytic removal of levofloxacin and mechanistic insight.

In this study, Sb2S3/In2S3/TiO2 (SIT) heterojunction photocatalysts were prepared by a simple two-step hydrothermal method and applied to the photocatalytic degradation of levofloxacin (LEV). After 160 min of reaction under visible light, the SIT heterojunction photocatalyst degraded 10 mg L-1 LEV at a rate of 86.7%. The degradation of LEV follows pseudo-first-order kinetics with a rate constant 1.16 × 10-2 min-1, which is 1.42, 1.22 and 1.05 times higher than that of TiO2, SI and IT, respectively. Meanwhile, the SIT photocatalysts also showed high photocatalytic activity for other antibiotics. The enhanced photocatalytic activity of the ternary heterostructures was attributed to the full-spectrum response and the synergistic effect of the dual Z-type heterojunctions, which improved the visible light absorption and facilitated the charge separation. In addition, ˙OH and ˙O2- play a dominant role in the photodegradation process. This work contributes to the design of novel photocatalytic materials with dual Z-type heterojunctions and efficient photocatalysts for the degradation of antibiotics.

Au nanoparticle sensitized blue TiO2 nanorod arrays for efficient Gatifloxacin photodegradation.

TiO2 nanorod arrays have been widely used in photocatalytic processes, but their poor visible light absorption and rapid carrier recombination limit their application. Both introducing oxygen vacancies and using precious metals as surface plasmon resonance (SPR) stimulators are effective strategies to enhance their photocatalytic performance. Herein, Au nanoparticle sensitized blue TiO2 nanorod arrays (Au/B-TiO2) were successfully fabricated for efficient Gatifloxacin photodegradation. The degradation efficiency of Gatifloxacin was up to 95.0%. Moreover, the corresponding reaction rate constant (Ka) was up to 0.02007 min-1. Additionally, it was suggested that Gatifloxacin could be subject to three different degradation pathways. The superior catalytic activity of Au/B-TiO2 is a result of the combined effect of the two components. Firstly, TiO2 nanorod arrays provide a larger surface area for Au deposition and act as efficient transfer channels. Secondly, the presence of oxygen vacancies in blue TiO2 nanorod arrays enhances the catalytic activity. Thirdly, Au acts as a SPR activator, providing a large number of high-energy electrons in the photocatalysis process. Lastly, the improved light capture capabilities are essential for efficient removal of Gatifloxacin. This work provides a new approach for the construction of a high-performance heterojunction photocatalyst in advanced oxidation processes.

Internal electric field-assisted copper ions chelated polydopamine/titanium dioxide nano-thin film heterojunctions activate peroxymonosulfate under visible light to catalyze degradation of gatifloxacin: Theoretical calculations and biotoxicity analysis.

The combination of photocatalysis and peroxymonosulfate (PMS) activation is considered effective in treating organic pollutants in water; however, the photocatalysts currently used to activate PMS are primarily in powder form, which cause secondary contamination because they are difficult to recycle. In this study, copper-ion-chelated polydopamine/titanium dioxide (Cu-PDA/TiO2) nanofilm were prepared for PMS activation on fluorine-doped tin oxide substrates using hydrothermal and in-situ self-polymerization methods. The results showed that Cu-PDA/TiO2 + PMS + Vis degraded 94.8% of gatifloxacin (GAT) within 60 min, and the reaction rate constant reached 4.928 × 10-2 min-1, which was 6.25 and 4.04 folds higher than that of TiO2 + PMS + Vis (0.789 × 10-2 min-1) and PDA/TiO2 + PMS + Vis (1.219 × 10-2 min-1), respectively. The Cu-PDA/TiO2 nanofilm is easily recyclable and activates PMS to degrade GAT with no inferior performance, unlike the powder-based photocatalysts, and simultaneously maintains outstanding stability, which is highly suitable for applications in real aqueous environments. Biotoxicity experiments were conducted using E. coli, S. aureus, and mung bean sprouts as experimental subjects, and the results showed that the Cu-PDA/TiO2 + PMS + Vis system had excellent detoxification ability. In addition, a detailed investigation of the formation mechanism of step-scheme (S-scheme) Cu-PDA/TiO2 nanofilm heterojunctions was conducted by density functional theory (DFT) calculations and in-situ X-ray photoelectron spectroscopy (XPS). Finally, a specific process for activating PMS to degrade GAT was proposed, which provides a novel photocatalysts for practical applications in aqueous pollution.

Zoledronic acid promotes osteoclasts ferroptosis by inhibiting FBXO9-mediated p53 ubiquitination and degradation.

Bisphosphonates (BPs)-related osteonecrosis of jaw (BRONJ) is a severe complication of the long-term administration of BPs. The development of BRONJ is associated with the cell death of osteoclasts, but the underlying mechanism remains unclear. In the current study, the role of Zoledronic acid (ZA), a kind of bisphosphonates, in suppressing the growth of osteoclasts was investigated and its underlying mechanism was explored. The role of ZA in regulating osteoclasts function was evaluated in the RANKL-induced cell model. Cell viability was assessed by cell counting kit-8 (CCK-8) assay and fluorescein diacetate (FDA)-staining. We confirmed that ZA treatment suppressed cell viability of osteoclasts. Furthermore, ZA treatment led to osteoclasts death by facilitating osteoclasts ferroptosis, as evidenced by increased Fe2+, ROS, and malonyldialdehyde (MDA) level, and decreased glutathione peroxidase 4 (GPX4) and glutathione (GSH) level. Next, the gene expression profiles of alendronate- and risedronate-treated osteoclasts were obtained from Gene Expression Omnibus (GEO) dataset, and 18 differentially expressed genes were identified using venn diagram analysis. Among these 18 genes, the expression of F-box protein 9 (FBXO9) was inhibited by ZA treatment. Knockdown of FBXO9 resulted in osteoclasts ferroptosis. More important, FBXO9 overexpression repressed the effect of ZA on regulating osteoclasts ferroptosis. Mechanistically, FBXO9 interacted with p53 and decreased the protein stability of p53. Collectively, our study showed that ZA induced osteoclast cells ferroptosis by triggering FBXO9-mediated p53 ubiquitination and degradation.

Effect of TiO2 arrays on surface enhanced Raman scattering (SERS) performance for Ag/TiO2 substrates.

Ag/TiO2 nanostructure arrays were constructed on fluorine-doped tin oxide (FTO) via a controllable hydrothermal route and a magnetron sputtering method with a variety of TiO2 arrays decorated by Ag nanoparticles. Effects of different TiO2 arrays on the microstructure, composition, and optical properties of the samples were revealed. As surface enhanced Raman scattering (SERS) active substrates, we discussed the sensitivity and reproducibility of Ag/TiO2 nanostructure arrays for Rhodamine 6G (R6G) molecule detection. It was found that TiO2 nanosheet (TiO2(S)) array as a supporting made Ag nanoparticles have a uniform and continuous distribution, which achieved much higher SERS signals. The obtained Ag/TiO2(S) substrate had an improved enhancement factor of 4.31 × 105 compared with the other Ag/TiO2 nanostructure arrays of nanorods, nanotubes, and nanotrees. Furthermore, Ag/TiO2(S) active substrate showed good reproducibility with low relative standard deviation values. Such a remarkable SERS activity could be due to the synergistic effect of electromagnetic enhancement and charge transfer enhancement. Moreover, the TiO2(S) array with high-exposed {101} facets provided a large adhesion area and generated a strong interaction with external atoms, which would produce high-density 'hot spots' of SERS.

A Facile and Controllable Vapor-Phase Hydrothermal Approach to Anionic S2--doped TiO2 Nanorod Arrays with Enhanced Photoelectrochemical and Photocatalytic Activity.

Anionic S2--doped TiO2 nanorod arrays (S2--TiO2) were synthesized by a facile and controllable vapor-phase hydrothermal (VPH) approach based on the sulfur source of H2S gas. After the VPH treatment of TiO2 nanorod arrays (TNA), the isolated O2- species replaces the S2- ion in TiO2 (TiO2-xSx). The structural, morphological, optical, compositional, photocatalytic and photoelectrochemical (PEC) properties of the obtained samples were investigated in detail. It was found that S2--TiO2 can enhance the separation rate of electron-hole pairs, improve the absorption of visible light, and augment the photocatalytic and photoelectrochemical properties. Anionic S2- doping can significantly adjust the absorption cut-off wavelength (409.5-542.5 nm) and shorten the bandgap (3.05-2.29 eV) of TNA. For the degradation of methylene orange (MO) under mercury lamp light, the 0.24 At%S2--TiO2 (0.24S2--TiO2) sample exhibited the best photogradation efficiency of 73% in 180 min compared to bare TiO2 (46%). The 0.24S2--TiO2 showed the highest photocurrent of 10.6 µA/cm2, which was 1.73 times higher than that of bare TiO2 (6.1µA/cm2). The results confirmed that the visible light absorption, photocurrent and photocatalytic activity optimization of TNA are closely related not only to anionic S2--doped but also different ratios of anionic S2--doped. It is noteworthy that the VPH approach is very promising for applications in low cost and highly efficient ion doping into nanomaterials for energy devices.

Interface chemistry modulation and dielectric optimization of TMA-passivated HfDyO x /Ge gate stacks using doping concentration and thermal treatment.

In this work, the effects of different Dy-doping concentrations and annealing temperatures on the interfacial chemistry and electrical properties of TMA-passivated HfDyO x /Ge gate stacks have been investigated systematically. The microstructural, optical, interfacial chemistry, and electrical characteristics of sputtering-driven HfDyO x gate dielectrics have been characterized by means of X-ray diffraction (XRD), UV-Vis transmission spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrical measurements. This work reveals that the interfacial chemistry evolution takes place via two competing processes, including oxide growth and oxide desorption. XPS analyses have confirmed that the 10 W-deposited targeted gate dielectrics display optimized interface characteristics, which can be attributed to the suppressed unstable Ge oxides and inhibition effects on inter-diffusion at the interface. Electrical observations show that the 10 W-driven HfDyO x /Ge MOS device without annealing treatment exhibits optimized electrical performance, including a larger permittivity of 22.4, a smaller flat band voltage of 0.07 V, vanishing hysteresis, a lowest oxide charge density of ∼1011 cm-2, and a lowest leakage current density of 2.31 × 10-8 A cm-2. Furthermore, the influences of doping and annealing conditions on the leakage current conduction mechanisms (CCMs) of HfDyO x /Ge MOS capacitors have also been investigated systematically. All of the experimental results indicate that TMA-passivated HfDyO x /Ge gate stacks with appropriate doping concentrations demonstrate potential application prospects for Ge-based MOSFET devices.

Construction of Ag-modified TiO2/ZnO heterojunction nanotree arrays with superior photocatalytic and photoelectrochemical properties.

The work involves the preparation of TiO2/ZnO heterojunction nanotree arrays by a three-step: hydrothermal, sol-gel, and secondary hydrothermal method, and then modification of Ag quantum dots (QDs). In the above process, the ZnO nanoparticles attached to the TiO2 surface were subjected to secondary growth by a hydrothermal method to form a unique nanotree structure with TiO2, followed by Ag quantum dot modification by quantum dot deposition. In summary, TiO2/ZnO nanotree arrays are cited for the first time. The prepared Ag-modified TiO2/ZnO heterojunction nanotree arrays were found to exhibit enhanced photoelectrochemical and photocatalytic properties. The photocurrent of the Ag-modified TiO2/ZnO heterojunction nanotree arrays is increased by 8-fold compared to the pure TiO2 nanorod arrays, the photocatalytic degradation rate within 180 minutes increased from 37% to 77% and the kinetic rate constants for the degradation of methyl orange were three times higher than the pure TiO2 nanorod arrays. The improved performance is partly due to the introduction of the TiO2/ZnO heterojunction nanotree arrays which provide Ag QDs with greater adhesion area. Localized surface plasmon resonance (LSPR) leads to an increase in the intensity of absorbed light due to the modification of Ag QDs. On the other hand the generation of the TiO2/ZnO heterojunction decreases the forbidden band width, resulting in the redshift of the light absorption edge. Therefore, TiO2/ZnO heterojunction nanotree arrays are expected to play an important role in solar cells and photocatalytic materials.

Hydrothermal synthesis of MoS2 nanosheet loaded TiO2 nanoarrays for enhanced visible light photocatalytic applications.

A molybdenum disulfide (MoS2) nanosheet-decorated titanium dioxide (TiO2) NRA heterojunction composite was fabricated successfully through a two-step hydrothermal approach. Microstructures and optical properties of specimens were characterized by field-emission scanning electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, and ultraviolet-visible spectroscopy. The gaps of the TiO2 nanorods have been filled with tiny MoS2 nanosheets, which can increase the surface area of MoS2/TiO2 NRA composite thin films. In addition, the photocatalytic activity of the thin films were measured and discussed in greater detail. The appropriate hydrothermal reaction temperature of MoS2 is important for the growth of perfect MoS2/TiO2 NRA composites with significantly enhanced photocatalytic performance. The photodegradation rate and k value of MoS2-220/TiO2 are 86% and 0.0105 min-1, respectively, which are much larger than those of blank TiO2. The enhanced photocatalytic performance could be attributed to the higher visible light absorption and the reduced recombination rate of photogenerated electron-hole pairs.

Microstructure and Doping/Temperature-Dependent Photoluminescence of ZnO Nanospears Array Prepared by Hydrothermal Method.

Al-doped ZnO nanospears were prepared by a hydrothermal method. The crystalline structure and photoluminescence properties of ZnO nanospears were characterized for investigating the effect of Al doping on the properties of ZnO nanospears. ZnO nanospears grow preferentially along the c-axis and have a fine tip. Al doping reduces the length of ZnO nanospears. In room temperature, photoluminescence spectra of Al-doped ZnO nanospears, a near band edge emission (~3.16 eV), and a violet emission (~2.91 eV) exhibit a strong doping-dependent characteristic and a temperature-independent characteristic, while deep level emission peak shows a temperature-dependent characteristic. In variable temperature, photoluminescence spectra near band edge emission (~3.31 eV) and its fine structures were observed when the measurement temperature is less than 57 K, and it shows an obvious temperature-dependent characteristic. The thermal quenching of this near band edge emission should be attributed to exciton scattering by defects and the presence of a high concentration of defects in Al-doped ZnO nanospears.

Facile Fabrication of Uniform MFe2O4 (M = Co, Ni, Cu) Hollow Spheres and Their Recyclable Superior Catalytic Activity Towards 4-Nitrophenol Reduction.

We have developed a facile, efficient, economic, and green method to fabricate uniform MFe2O4 (M Co, Ni, Cu) hollow spheres by using polyacrylamide (PAM) as an additive agent. The as-obtained three types of hollow ferrites are employed to catalyze the reductive transformation of nitrophenols to aminophenols, which exhibit excellent catalytic activity. The kinetics of the catalytic reaction follows the quasi-first order reaction and its rate constant (kapp) values for CoFe2O4, NiFe2O4 and CuFe2O4 are calculated to be 1.62, 11.74 and 37.28 min-1, respectively. These data are higher than those former reports which using similar reactions catalyzed by different nanocatalysts. Among the three catalysts, NiFe2O4 and CuFe2O4 can be successfully reused for at least six consecutive cycles and have a stable conversion efficiency of about 100%, while CoFe2O4 is catalytically inactive after three cycles. The superiority of the catalytic reduction of NiFe2O4 and CuFe2O4 may be due to their soft magnetic properties as well as their better separation efficiency of the electron-hole pairs. Thus it is expected that these two recyclable hollow ferrites will be used commercially in the treatment of aromatic nitro compounds in industrial wastewater.

Potential solution-induced HfAlO dielectrics and their applications in low-voltage-operating transistors and high-gain inverters.

Recently, much attention has been paid to the investigation of solution-driven oxides for application in thin film transistors (TFTs). In current study, a fully solution-based method, using 2-methoxyethanol as solvent, has been adopted to prepare InZnO thin films and HfAlO x gate dielectrics. Amorphous HfAlO x thin films annealed at 600 °C have shown a high transparency (>85%), low leakage current density (6.9 × 10-9 A cm-2 at 2 MV cm-1), and smooth surface. To verify the potential applications of HfAlO x gate dielectrics in oxide-based TFTs, fully solution-induced InZnO/HfAlO x TFTs have been integrated. Excellent electrical performance for InZnO/HfAlO x TFTs annealed at 450 °C has been observed, including a low operating voltage of 3 V, a saturated mobility of 5.17 cm2 V-1 s-1, a high I on/I off of ∼106, a small subthreshold swing of 87 mV per decade, and a threshold voltage shift of 0.52 V under positive bias stress (PBS) for 7200 s, respectively. In addition, time dependent threshold voltage shift under PBS could be described by a stretched-exponential model, which can be due to charge trapping in the semiconductor/dielectric interface. Finally, to explore the possible application in logic operation, a resistor-loaded inverter based on InZnO/HfAlO x TFTs has been built and excellent swing characteristic and well dynamic behavior have been obtained. Therefore, it can be concluded that fully solution-driven InZnO/HfAlO x TFTs have demonstrated potential application in nontoxic, eco-friendly and low-power consumption oxide-based flexible electronics.

Enhanced photoelectrochemical properties of nanocrystalline TiO2 electrode by surface sensitization with CuxO quantum dots.

Nanoporous anatase TiO2 films were fabricated by a screen-printing method, and CuxO quantum dots (QDs) were deposited on the TiO2 films through successive ionic layer adsorption and reaction (SILAR). The amount of CuxO QDs on the TiO2 films are controlled by changing the number of SILAR cycles. The morphology, microstructure, optical, and photoelectrochemical properties of different CuxO sensitized TiO2 films (CuxO/TiO2) were investigated in detail. The nanoporous TiO2 film offers a large surface area for anchoring QDs. QD deposited samples exhibited a significant improvement in photoelectrochemical performance than the bare of TiO2. CuxO/TiO2, prepared with 7 SILAR cycles, showed the best photoelectrochemical properties, where the photocurrent density was enhanced to 500.01 µA/cm2 compared with 168.88 µA/cm2 of bare TiO2 under visible light. These results indicate that the designed CuxO/TiO2 structure possesses superior charge separation efficiency and photoelectrochemical properties.

Rational Design of α-Fe2O3/Reduced Graphene Oxide Composites: Rapid Detection and Effective Removal of Organic Pollutants.

α-Fe2O3/reduced graphene oxide (α-Fe2O3/rGO) composites are rationally designed and prepared to integrate organic pollutants detection and their photocatalytic degradation. Specifically, the composites are used as the substrate for surface-enhanced Raman scattering (SERS) to detect rhodamine 6G (R6G). Repeatable strong SERS signals could be obtained with R6G concentration as low as 10(-5) M. In addition, the substrate exhibits self-cleaning properties under solar irradiation. Compared with pure α-Fe2O3 and α-Fe2O3/rGO mechanical mixtures, the α-Fe2O3/rGO composites show much higher photocatalytic activity and much greater Raman enhancement factor. After 10 cycling measurements, the photodegradation rate of R6G could be maintained at 90.5%, indicating high stability of the photocatalyst. This study suggests that the α-Fe2O3/rGO composites would serve both as recyclable SERS substrate and as excellent visible light photocatalyst.

Microstructure, optical properties, and catalytic performance of Cu2O-modified ZnO nanorods prepared by electrodeposition.

Cu2O-modified ZnO nanorods are prepared by a two-step electrodeposition method on ITO substrates, and the deposition time of Cu2O is 0, 1, 5, and 10 min, respectively. Cu2O particles are embedded in the interspaces of the ZnO nanorods, and the amounts of the Cu2O particles increase obviously when the deposition time lasts longer. The peaks corresponding to ZnO nanorods and Cu2O particles are detected from scanning electron microscope (SEM) and X-ray diffraction (XRD) results. UV-vis absorption spectra measurements have shown the bandgaps of ZnO nanorods shift from 3.22 to 2.75 eV. The methyl orange (MO) concentration can be reduced to around 15% in 100 min with Cu2O electrodeposition time for 10 min.

Facile synthesis of iron oxides/reduced graphene oxide composites: application for electromagnetic wave absorption at high temperature.

Iron oxides/reduced graphene oxide composites were synthesized by facile thermochemical reactions of graphite oxide and FeSO4 · 7H2O. By adjusting reaction temperature, α-Fe2O3/reduced graphene oxide and Fe3O4/reduced graphene oxide composites can be obtained conveniently. Graphene oxide and reduced graphene oxide sheets were demonstrated to regulate the phase transition from α-Fe2O3 to Fe3O4 via γ-Fe2O3, which was reported for the first time. The hydroxyl groups attached on the graphene oxide sheets and H2 gas generated during the annealing of graphene oxide are believed to play an important role during these phase transformations. These samples showed good electromagnetic wave absorption performance due to their electromagnetic complementary effect. These samples possess much better electromagnetic wave absorption properties than the mixture of separately prepared Fe3O4 with rGO, suggesting the crucial role of synthetic method in determining the product properties. Also, these samples perform much better than commercial absorbers. Most importantly, the great stability of these composites is highly advantageous for applications as electromagnetic wave absorption materials at high temperatures.

A series of Zn(ii) terpyridine complexes with enhanced two-photon-excited fluorescence for in vitro and in vivo bioimaging.

It is still a challenge to obtain two-photon excited fluorescent bioimaging probes with intense emission, high photo-stability and low cytotoxicity. In the present work, four Zn(ii)-coordinated complexes (1-4) constructed from two novel D-A and D-π-A ligands (L1 and L2) are investigated both experimentally and theoretically, aiming to explore efficient two-photon probes for bioimaging. Molecular geometry optimization used for theoretical calculations is achieved using the crystallographic data. Notably, the results indicate that complexes 1 and 2 display enhanced two-photon absorption (2PA) cross sections compared to their corresponding D-A ligand (L1). Furthermore, it was found that complex 1 has the advantages of moderate 2PA cross section in the near-infrared region, longer fluorescence lifetime, higher quantum yield, good biocompatibility and enhanced two-photon excited fluorescence. Therefore, complex 1 is evaluated as a bioimaging probe for in vitro imaging of HepG2 cells, in which it is observed under a two-photon scanning microscope that complex 1 exhibits effective co-staining with endoplasmic reticulum (ER) and nuclear membrane; as well as for in vivo imaging of zebrafish larva, in which it is observed that complex 1 exhibits specificity in the intestinal system.

Modulating the interface quality and electrical properties of HfTiO/InGaAs gate stack by atomic-layer-deposition-derived Al2O3 passivation layer.

In current work, the effect of the growth cycles of atomic-layer-deposition (ALD) derived ultrathin Al2O3 interfacial passivation layer on the interface chemistry and electrical properties of MOS capacitors based on sputtering-derived HfTiO as gate dielectric on InGaAs substrate. Significant suppression of formation of Ga-O and As-O bond from InGaAs surface after deposition of ALD Al2O3 with growth cycles of 20 has been achieved. X-ray photoelectron spectroscopy (XPS) measurements have confirmed that suppressing the formation of interfacial layer at HfTiO/InGaAs interface can be achieved by introducing the Al2O3 interface passivation layer. Meanwhile, increased conduction band offset and reduced valence band offset have been observed for HfTiO/Al2O3/InGaAs gate stack. Electrical measurements of MOS capacitor with HfTiO/Al2O3/InGaAs gate stacks with dielectric thickness of ∼4 nm indicate improved electrical performance. A low interface-state density of (∼1.9) × 10(12) eV(-1) cm(-2) with low frequency dispersion ( ∼ 3.52%), small border trap density of 2.6 × 10(12) cm(-2), and low leakage current of 1.17 × 10(-5) A/cm(2) at applied gate voltage of 1 V have been obtained. The involved leakage current conduction mechanisms for metal-oxide-semiconductor (MOS) capacitor devices with and without Al2O3 interface control layer also have been discussed in detail.

Capability of coupled CdSe/TiO2 heterogeneous structure for photocatalytic degradation and photoconductivity.

Highly ordered TiO2 nanotube arrays (TiO2-NTAs), with a uniform tube size on titanium substrate, were obtained by means of reoxidation and annealing. A composite structure, CdSe quantum dots@TiO2 nanotube arrays (CdSe QDs@TiO2-NTAs), was fabricated by assembling CdSe quantum dots into TiO2-NTAs via cyclic voltammetry electrochemical deposition. The X-ray diffractometer (XRD), field-emission scanning electron microscope (SEM), and transmission electron microscope (TEM) were carried out for the determination of the composition and structure of the tubular layers. Optical properties were investigated by ultraviolet-visible spectrophotometer (UV-Vis). Photocurrent response under visible light illumination and photocatalytic activity of samples by degradation of methyl orange were measured. The results demonstrated that the photo absorption of the composite film shifted to the visible region, and the photocurrent intensity was greatly enhanced due to the assembly of CdSe QDs. Especially, photocurrent achieved a maximum of 1.853 µA/cm(2) after five voltammetry cycles of all samples. After irradiation under ultra violet-visible light for 2 h, the degradation rate of composition to methyl orange (MO) reached 88.20%, demonstrating that the CdSe QDs@TiO2-NTAs exhibited higher photocatalytic activity.

Effect of annealing temperature on wettability of TiO2 nanotube array films.

Highly ordered TiO2 nanotube array (TN) films were prepared by anodization of titanium foil in a mixed electrolyte solution of glycerin and NH4F and then annealed at 200°C, 400°C, 600°C, and 800°C, respectively. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle (WCA), and photoluminescence (PL). It was found that low temperature (below 600°C) has no significant influence on surface morphology, but the diameter of the nanotube increases from 40 to 50 nm with increasing temperature. At 800°C, the nanotube arrays are completely destroyed and only dense rutile film is observed. Samples unannealed and annealed at 200°C are amorphous. At 400°C, anatase phase appears. At 600°C, rutile phase appears. At 800°C, anatase phase changes into rutile phase completely. The wettability of the TN films shows that the WCAs for all samples freshly annealed at different temperatures are about 0°. After the annealed samples have been stored in air for 1 month, the WCAs increase to 130°, 133°, 135°, 141°, and 77°, respectively. Upon ultraviolet (UV) irradiation, they exhibit a significant transition from hydrophobicity to hydrophilicity. Especially, samples unannealed and annealed at 400°C show high photoinduced hydrophilicity.