Growth of TiO_2 Nanorods by Sol-gel Template Process

In this work, TiO2 nanorods with uniform diameter of about 100 nm and a length of several micrometers were successfully prepared by the sol-gel template method. Also the influence of molar ratios of precursor on the morphology and structure of TiO2 nanorods has been investigated. The prepared samples were characterized by Fourier transform infrared spectroscopy （FTIR）, X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The XRD results indicated that the TiO2 nanorods were crystallized in the anatase and rutile phases, after annealing to 400-700℃ up to 2 h.

Synthesis and application of TiO_2 single-crystal nanorod arrays grown by multicycle hydrothermal for dye-sensitized solar cells

TiO2 is a wide band gap semiconductor with important applications in photovoltaic cells. Vertically aligned Tit2 nanorod arrays （NRs） are grown on the fluorine-doped tin oxide （FTO） substrates by a multicycle hydrothermal synthesis process. The samples are characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high-resolution transmission electron microscopy （HRTEM）, and selected-area electron diffraction （SAED）. It is found that dye-sensitized solar cells （DSSCs） assembled by the as-prepared Tit2 single-crystal NRs exhibit different trends under the condition of different nucleation and growth concentrations. Optimum cell performance is obtained with high nucleation concentration and low growth cycle concentration. The efficiency enhancement is mainly attributed to the improved specific surface area of the nanorod.

Composite Semiconductor Quantum Dots CdSe/CdS Co-sensitized TiO_2 Nanorod Array Solar Cells

CdSe/CdS semiconductor quantum dots co-sensitized TiO2 nanorod array was fabricated on the transparent conductive fluorine-doped tin oxide （FTO） substrate using the hydrothermal and successive ionic layer adsorption and reaction （SILAR） process. The structural and morphological properties of the samples were characterized by X-ray diffraction （XRD）, field-emission scanning electron microscopy （FESEM）, and transmission electron microscopy （TEM）. The results indicate that CdSe/CdS QDs are uniformly coated on the surface of the TiO2 nanorods. The shift of light absorption edge was monitored by taking UV-visible absorption spectra. Compared with the absorption spectra of the TiO2 nanorod array, deposition of CdSe/CdS QDs shifts the absorption edge to the higher wavelength. The enhanced light absorption in the visible-light region of CdSe/CdS/TiO2 nanorod array indicates that CdSe/CdS layers can act as co-sensitizers in quantum dots sensitized solar cells （QDSSCs）. By optimizing the CdSe layer deposition cycles, a photocurrent of 5.78 mA/cm2, an open circuit photovoltage of 0.469 V and a conversion efficiency of 1.34 % were obtained under an illumination of 100 mw/cm2.

Effect of hydroxyl on dye-sensitized solar cells assembled with TiO_2 nanorods

YiO2 nanorods have been prepared on ITO substrates by dc reactive magnetron sputtering technique. The hydroxyl groups have been introduced on the nanorods surface. The structure and the optical properties of these nanorods have been studied. The dye-sensitized solar cells （DSSCs） have been assembled using these TiO2 nanorods as photoelectrode. And the effect of the hydroxyl groups on the properties of the photoelectric conversion of the DSSCs has been studied.

420nm thick CH_3NH_3PbI_(3-x)Br_x capping layers for efficient TiO_2 nanorod array perovskite solar cells

The rutile TiO2 nanorod arrays with 240 nm in length, 30 nm in diameter, and 420 btm 2 in areal density were prepared by the hydrothermal method to replace the typical 200-300 nm thick mesoporous TiO2 thin films in perovskite solar cells. The CH3NH3PbI3 xBrx capping layers with different thicknesses were obtained on the TiO2 nanorod arrays using different concentration PbI2.DMSO complex precursor solutions in DMF and the photovoltaic performances of the corresponding solar cells were compared. The perovskite solar cells based on 240 nm long TiO2 nanorod arrays and 420 nm thick CH3NH3PbI3 xBrx capping layers showed the best photoelectric conversion efficiency （PCE） of 15.56% and the average PCE of 14.93 ± 0.63% at the relative humidity of 50%-54% under the illumination of simulated AM 1.5 sunlight （100 mW.cm-2）.

Synthesis of Single-Crystalline Anatase TiO_2 Nanorods With High-Performance Dye-Sensitized Solar Cells

Single-crystalline anatase TiO2nanorods have been prepared by solvothermal method using tetrabutylammonium hydroxide（TBAH） as a morphology controlling agent.The obtained TiO2nanorods are dominated by a large percentage of {010} facets.The power conversion efficiency of dye-sensitized solar cell（DSSC） based on anatase TiO2nanorods（8.66%） exhibits a significant improvement（35%） compared to that of P25 TiO2（5.66%）.The high performance of the anatase TiO2nanorods solar cell is ascribed to their large percent of exposed {010} facets as well as balancing their surface areas and sizes.

Enhancing photocatalytic performance by constructing ultrafine TiO2 nanorods/g-C3N4 nanosheets heterojunction for water treatment

Photocatalysis is considered to be a clean, green and efficient method to purify water. In this report, we first developed a highly efficient ultrafine TiO2 nanorods/g-C3N4 nanosheets （TiO2 NR/CN NS） composites via a simple hydrothermal method. Tiny TiO2 nanorods （diameter： ～1.5 nm and length： ～8.3 nm） were first loaded in situ on the CN NS by adding graphitic carbon nitride （g-C3N4） to the reaction solution. The TiO2 NR/CN NS composites present high charge separation efficiency and broader light absorbance than P25 TiO2. Furthermore, we illustrate that the TiO2 NR/CN NS catalyst possesses high performance for the photocatalytic degradation of the common and stubborn pollutants in water, such as the rhodamine B （RhB） dye and phenol. Under visible light （λ 〉 420 nm） irradiation, the apparent rate of the TiO2 NR/CN NR is 172 and 41 times higher than that of the P25 TiO2 and TiO2 NR, respectively. Additionally, we speculated that the heterojunction formed between TiO2 NR and CN NS, which is the basis for the experiments we have designed and the corresponding results. We demonstrated that reactive oxidative species such as superoxide anion radical and holes play critical roles in the degradation, and the hydroxyl radical contributes nothing to the degradation.

Photocatalytic degradation evaluation of N–Fe codoped aligned TiO2 nanorods based on the effect of annealing temperature

In this paper,a comparative study on the photocatalytic degradation of the Rhodamine B(Rh B)dye as a model compound using N–Fe codoped Ti O2 nanorods under UV and visible-light(λ≥420 nm)irradiations has been performed.Ti O2 photocatalysts were fabricated as aligned nanorod arrays by liquid-phase deposition process,annealed at different temperatures from 400 to 800℃.The effects of annealing temperature on the phase structure,crystallinity,BET surface area,and resulting photocatalytic activity of N–Fe codoped Ti O2 nanorods were also investigated.The degradation studies confirmed that the nanorods annealed at 600℃composed of both anatase(79%)and rutile phases(21%)and offered the highest activity and stability among the series of nanorods,as it degraded 94.8%and 87.2%Rh B in 120 min irradiation under UV and visible-light,respectively.Above 600℃,the photocatalytic performance of nanorods decreased owning to a phase change,decreased surface area and bandgap,and growth of Ti O2 crystallites induced by the annealing temperature.It is hoped that this work could provide precious information on the design of 1 D catalyst materials with more superior photodegradation properties especially under visible-light for the further industrial applications.

Synergistic antibacterial activity of physical-chemical multi-mechanism by TiO2 nanorod arrays for safe biofilm eradication on implant

Treatment of implant-associated infection is becoming more challenging,especially when bacterial biofilms form on the surface of the implants.Developing multi-mechanism antibacterial methods to combat bacterial biofilm infections by the synergistic effects are superior to those based on single modality due to avoiding the adverse effects arising from the latter.In this work,TiO2 nanorod arrays in combination with irradiation with 808 nearinfrared(NIR)light are proven to eradicate single specie biofilms by combining photothermal therapy,photodynamic therapy,and physical killing of bacteria.The TiO2 nanorod arrays possess efficient photothermal conversion ability and produce a small amount of reactive oxygen species(ROS).Physiologically,the combined actions of hyperthermia,ROS,and puncturing by nanorods give rise to excellent antibacterial properties on titanium requiring irradiation for only 15 min as demonstrated by our experiments conducted in vitro and in vivo.More importantly,bone biofilm infection is successfully treated efficiently by the synergistic antibacterial effects and at the same time,the TiO2 nanorod arrays improve the new bone formation around implants.In this protocol,besides the biocompatible TiO2 nanorod arrays,an extra photosensitizer is not needed and no other ions would be released.Our findings reveal a rapid bacteria-killing method based on the multiple synergetic antibacterial modalities with high biosafety that can be implemented in vivo and obviate the need for a second operation.The concept and antibacterial system described here have large clinical potential in orthopedic and dental applications.

In situ growth of single-crystal TiO2 nanorod arrays on Ti substrate： Controllable synthesis and photoelectro- chemical water splitting

Despite one-dimensional （1D） semiconductor nanostructure arrays attracting increasing attention due to their many advantages, highly ordered TiO2 nanorod arrays （TiO2 NR） are rarely grown in situ on Ti substrates. Herein, a feasible method to fabricate TiO2 NRs on Ti substrates by using a through-mask anodization process is reported. Self-ordered anodic aluminum oxide （AAO） overlaid on Ti substrate was used as a nanotemplate to induce the growth of TiO2 NRs. The NR length and diameter could be controlled by adjusting anodization parameters such as electrochemical anodization voltage, anodization time and temperature, and electrolyte composition. Furthermore, according to the proposed NR formation mechanism, the anodized Ti ions migrate and deposit in the AAO nanochannels to form Ti（OH）4 or amorphous TiO2 NRs under electric field, owing to the confinement effect of the template. Photoelectrochemical tests indicated that, after hydrogenation, the TiO2 NRs presented higher photocurrent density under simulated sunlight and visible light illuminations, suggesting their potential use in photoelectrochemical water splitting, photocatalysis, solar cells, and sensors.

A titanium dioxide nanorod array as a high-affinity nano-bio interface of a microfluidic device for efficient capture of circulating tumor cells

Nanomaterials show promising opportunities to address clinical problems （such as insufficient capture of circulating tumor cells; CTCs） via the high surface area-to-volume ratio and high affinity for biological cells. However, how to apply these nanomaterials as a nano-bio interface in a microfluidic device for efficient CTC capture with high specificity remains a challenge. In the present work, we first found that a titanium dioxide （TiO2） nanorod array that can be conveniently prepared on multiple kinds of substrates has high affinity for tumor cells. Then, the TiO2 nanorod array was vertically grown on the surface of a microchannel with hexagonally patterned Si micropillars via a hydrothermal reaction, forming a new kind of a micro-nano 3D hierarchically structured microfluidic device. The vertically grown TiO2 nanorod array was used as a sensitive nano-bio interface of this 3D hierarchically structured microfluidic device, which showed high efficiency of CTC capture （76.7% ± 7.1%） in an artificial whole-blood sample.

Hybrid UV photodetector with high photo-to-dark current ratio based on ordered TiO_2 nanorod arrays and polystyrene sulfate

Vertically aligned TiO2nanorods arrays were successfully synthesized on FTO glass by wet-chemical method.Based on polystyrene sulfate(PSS)functionalized TiO2nanorods arrays,a sandwich-structured hybrid UV photodetector was fabricated.The photo-to-dark current ratio of the device increases by more than 3 orders of magnitude with typical case,while the dark current is about 10 nA at 1 V bias.The high photoresponse together with the low dark current could probably contribute a large photocurrent and low-power application.The high performance of the hybrid material and facile low-cost fabrication of the UV detector make the devices promising for large-area UV photodetection applications.