Uniform nanoplating of metallic magnesium film on titanium dioxide nanotubes as a skeleton for reversible Na metal anode

To meet the low-cost concept advocated by the sodium metal anode,this paper reports the use of a pulsed electrodeposition technology with ionic liquids as electrolytes to achieve uniform nanoplating of metallic magnesium films at around 20 nm on spaced titanium dioxide(TiO_(2))nanotubes(STNA-Mg).First,the sodiophilic magnesium metal coating can effectively reduce the nucleation overpotential of sodium metal.Moreover,three-dimensional STNA can limit the volume expansion during sodium metal plating and stripping to achieve the ultrastable deposition and stripping of sodium metals with a high Coulombic efficiency of up to 99.5%and a small voltage polarization of 5 mV in symmetric Na||Na batteries.In addition,the comparative study of sodium metal deposition behavior of STNA-Mg and STNA-Cu prepared by the same route further confirmed the advantage of magnesium metal to guide sodium metal growth.Finally,the prepared STNA-Mg-Na metal anode and commercial sodium vanadium phosphate cathode were assembled into a full cell,delivering a discharge capacity of 110.2 mAh·g^(-1)with a retention rate of 95.6%after 110 cycles at 1C rate.

Impact of Annealing Treatment on the Behaviour of Titanium Dioxide Nanotube Layers

In this work, we study the influence of the annealing treatment on the behaviour of titanium dioxide nanotube layers. The heat treatment protocol is actually the key parameter to induce stable oxide layers and needs to be better understood. Nanotube layers were prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution during 20 minutes and then annealed in air atmosphere. In-situ X-ray diffraction analysis, coupled with thermogravimetry, gives us an inside on the oxidation behaviour of titanium dioxide nanotube layers compared to bulk reference samples. Structural studies were performed at 700°C for 12 h in order to follow the time consequences on the oxidation of the material, in sufficient stability conditions. In-situ XRD brought to light that the amorphous oxide layer induced by anodization is responsible for the simultaneous growths of anatase and rutile phase during the first 30 minutes of annealing while the bulk sample oxidation leads to the nucleation of a small amount of anatase TiO2. The initial amorphous oxide layer created by anodization is also responsible for the delay in crystallization compared to the bulk sample. Thermogravimetric analysis exhibits parabolic shape of the mass gain for both anodized and bulk sample;this kinetics is caused by the formation of a rutile external protective layer, as depicted by the associated in-situ XRD diffractograms. We recorded that titanium dioxide nanotube layers exhibit a lower mean mass gain than the bulk, because of the presence of an initial amorphous oxide layer on anodized samples. In-situ XRD results also provide accurate information concerning the sub-layers behavior during the annealing treatment for the bulk and nanostructured layer. Anatase crystallites are mainly localized at the interface oxide layer-metal and the rutile is at the external interface. Sample surface topography was characterized using scanning electron microscopy (SEM). As a probe of the photoactivity of the annealed TiO2 nanotube layers, degradation of an acid orange 7 (AO7) dye solution and 4-chlorophenol under UV irradiation (at 365 nm) were performed. Such titanium dioxide nanotube layers show an efficient photocatalytic activity and the analytical results confirm the degradation mechanism of the 4-chlorophenol reported elsewhere.

EFFECTS OF INHALED TiO_2 NANOTUBES ON LUNG TISSUE AND SERUM BIOCHEMICAL INDEXES OF MICE

To evaluate the acute lung toxicity and the effect on serum biochemical indexes of inhaled TiO2 nanotubes , healthy and adult Kunming mice are exposed to aerosols of TiO2nanotubes in a sealed chamber , the concentration of which is 250mg / m 3 while another group of mice are exposed to room air only served as control.The blood , alveolar lavaged fluid and lungs of the mice are collected and examined after exposed for 7 , 14and 28d , respectively.The serum analysis shows that glucose ( Glu ) values with 7dexposure , alanine aminotransferase ( ALT ) and aspartate aminotransferase ( AST ) activities with 28dinhalation , and total bile acid ( TBA ) values with 7 , 28d as well as the creatine kinase ( CK ) levels with 28dexposure are significantly different from those of controls ( P< 0.05 ) .The pathological findings exhibit that more TiO 2 nanotubes are found in the interstitium of pulmonary alveoli with the experimental time prolonged.The results suggest that TiO 2 nanotubes do produce adverse responses to the lung and serum biochemical indexes of mice.Moreover , the responses become severer with the exposed-time prolonged.

Feasibility of a Chronic Foreign Body Infection Model Studying the Influence of TiO2 Nanotube Layers on Bacterial Contamination

Bacterial infections on the surface of medical devices are a significant problem in therapeutic approach, especially when implants are used in the living. In cardiology, pacemaker generator pocket surfaces, made in titanium alloy can be colonized by pathogen microorganism. This contamination represents a major risk of sepsis, endocarditis and localized infections for patients. A way to limit this bacterial contamination is to modify the surface topography using nano-structuration process of the titanium alloy surface of the implanted devices. The aim of this study is to evaluate the influence of TiO2 nanotube layers on bacterial infection in the living, considering the feasibility of an animal model of chronic foreign body infection. TiO2 nanotube layers prepared by electrochemical anodization of Ti foil in 0.4 wt% hydrofluoric acid solution were implanted subcutaneously in Wistar rats. Three weeks after implantation, TiO2 implants were contaminated by a Staphylococcus epidermilis strain using two different concentrations at 106 and 108 colony forming unit (CFU) in order to induce a sufficient infection level and to avoid unwanted over infection consequences on rats health during the experiments. After 28 days in the living, 75% of nanotube layers initially submitted to the 108 CFU inoculum were contaminated while only 25% nanotube layers initially submitted to the 106 CFU inoculum remained infected. This significant result underlines the influence of TiO2 nanotube layers in decreasing the infection level. Our in vitro experiments showed that the synthesized TiO2 nanotubes indeed decreased the Staphylococcus epidermilis adhesion compared to unanodized Ti foil.

Heterostructured ZnFe_2O_4/Fe_2TiO_5/TiO_2 Composite Nanotube Arrays with an Improved Photocatalysis Degradation Efficiency Under Simulated Sunlight Irradiation

To improve the visible light absorption and photocatalytic activity of titanium dioxide nanotube arrays(TONTAs), ZnFe_2O_4(ZFO) nanocrystals were perfused into pristine TONTA pipelines using a novel bias voltageassisted perfusion method. ZFO nanocrystals were well anchored on the inner walls of the pristine TONTAs when the ZFO suspensions(0.025 mg m L^(-1)) were kept under a60 V bias voltage for 1 h. After annealing at 750 °C for2 h, the heterostructured ZFO/Fe_2 TiO_5(FTO)/TiO_2 composite nanotube arrays were successfully obtained. Furthermore, Fe^(3+)was reduced to Fe^(2+)when solid solution reactions occurred at the interface of ZFO and the pristine TONTAs. Introducing ZFO significantly enhanced thevisible light absorption of the ZFO/FTO/TONTAs relative to that of the annealed TONTAs. The coexistence of type I and staggered type II band alignment in the ZFO/FTO/TONTAs facilitated the separation of photogenerated electrons and holes, thereby improving the efficiency of the ZFO/FTO/TONTAs for photocatalytic degradation of methylene blue when irradiated with simulated sunlight.

Hydrophilic/underwater superoleophobic graphene oxide membrane intercalated by TiO2 nanotubes for oil/water separation

Membrane technology for oil/water separation has received increasing attention in recent years. In this study, the hydrophilic/underwater superoleophobic membrane with enhanced water permeability and antifouling ability were fabricated by synergistically assembling graphene oxide （GO） nanosheets and titanium dioxide （TiO2） nanotubes for oil/water separation. GO/TiO2 membrane exhibits hydrophilic and underwater superoleophobic properties with water contact angle of 62° and under water oil contact angle of 162.8°. GO/TiO2 membrane shows greater water permeability with the water flux up to 531 L/ （m^2·h·bar）, which was more than 5 times that of the pristine GO membrane. Moreover, GO/TiO2 membrane had excellent oil/water separation efficiency and anti-oil-fouling capability, as oil residual in filtrate after separation was below 5 mg/L and flux recovery ratios were over 80%.The results indicate that the intercalation of TiO2 nanotubes into adjacent GO nanosheets enlarged the channel structure and modified surface topography of the obtained GO/TiO2 membranes, which improved the hydrophilicity, permeability and anti-oil-fouling ability of the membranes, enlightening the great prospects of GO/TiO2 membrane in oil-water treatment.

Development of a field enhanced photocatalytic device for biocide of coliform bacteria

A field enhanced flow reactor using bias assisted photocatalysis was developed for bacterial disinfection in lab-synthesized and natural waters. The reactor provided complete inactivation of contaminated waters with flow rates of 50 mL/min. The device consisted of titanium dioxide nanotube arrays, with an externally applied bias of up to 6 V. Light intensity, applied voltage, background electrolytes and bacteria concentration were all found to impact the device performance. Complete inactivation of Escherichia coli W3110（- 8 × 10^3CFU/mL） occurred in 15 sec in the reactor irradiated at 25 mW/cm^2 with an applied voltage of 4 V in a 100 ppm NaCl solution. Real world testing was conducted using source water from Emigration Creek in Salt Lake City, Utah. Disinfection of natural creek water proved more challenging, providing complete bacterial inactivation after 25 sec at 6 V. A reduction in bactericidal efficacy was attributed to the presence of inorganic and organic species, as well as the increase in robustness of natural bacteria.

Decoration of vertically aligned TiO2 nanotube arrays with WO3 particles for hydrogen fuel production

WO3 decorated photoelectrodes of titanium nanotube arrays （W-oxide TNTAs） were synthesized via a two-step process, namely, electrochemical oxidation of titanium foil and electrodeposition of W-oxide for various interval times of 1, 2, 3, 5, and 20 min to improve the photoelectrochemical performance and the amount of hydrogen generated. The synthesized photoelectrodes were characterized by various characterization techniques. The presence of tungsten in the modified TNTAs was confirmed using energy dispersive X-ray spectroscopy （EDX）. Field emission scanning electron microscopy （FESEM） and high resolution transmission electron microscope （HRTEM） proved the deposition of W-oxide as small particles staked up on the surface of the tubes at lower deposition time whereas longer times produced large and aggregate particles to mostly cover the surface of TiO2 nanotubes. Additionally, the incorporation of WO3 resulted in a shift of the absorption edge toward visible light as confirmed by UV-Vis diffuse reflectance spectroscopy and a decrease in the estimated band gap energy values hence, modified TNTAs facilitated a more efficient utilization of solar light for water splitting. From the photoelectrochemical measurement data, the optimal photoelectrode produced after 2 min of deposition time improved the photo conversion efficiency and the hydrogen generation by 30% compared to that of the pure TNTA.

Photoelectrochemical performance of TiO_(2) nanotube arrays by in situ decoration with different initial states

Here,carbon dots(CDs) only or nanocomposites of CDs and TiO_(2)(CDs-TiO_(2)) were used to decorate titanium dioxide nanotube arrays(TiO_(2)NTs) in situ by solvothermal method.Two initial states of TiO_(2)NTs were prepared for contrast,including the amorphous TiO_(2)NTs(TiO_(2)NTs-0) just experienced anodic oxidation process and that further calcined TiO_(2)NTs(TiO_(2)NTs-450).It was found that the newborn CDs or CDs-TiO_(2)were more likely to anchor on TiO_(2)NTs-0 than the calcined TiO_(2)NTs-450,and more Ti-C bonds were found in the composites which were derived from TiO_(2)NTs-0 after the solvothermal treatment.An evident photocurrent could be demonstrated for either CDs or CDs-TiO_(2)decorated TiO_(2)NTs once exposed to visible light.And CDs-TiO_(2)NTs-0 showed the highest photocurrent density(4.51 μA·cm^(-2)).However,the results of photodegradation measurements revealed that CDs-TiO_(2)decorated TiO_(2)NTs with different initial states(especially CDs-TiO_(2)-TiO_(2)NTs-0) showed more excellent photocatalytic activity under both ultraviolet(UV) and visible light illumination.

Anodic-biased titania nanotube growth in low-dielectric viscous media

The influence was investigated of aqueous electrolytes and organic-based electrolytes on nanopore growth.To create well-defined nanotubes with a high aspect ratio,it is important to maintain equilibrium between field-assisted metal oxide dissolution and field-assisted water dissociation,which influence the temperature and pH levels in TiO_(2) nanotubes(TiO_(2) NTs).This sought after balance in the net reactions of the TiO_(2) NT growth can be achieved by choosing the appropriate electrolytes that are a relatively low dielectric viscous media.Viscosity(η)and dielectrics(ε)can be a priority in designing the experiment since it is closely related to joule-heating,diffusion-driven metal ions dissolution and chemical etching of the metal oxide.Solvation and the hydrogen bonding ability are inter-correlated to the stability of the[TiF_(6)]^(2-) complex.In order to examine various electrolyte effects on the anodic-biased nanotube,different categories of electrolytes,each with different viscosity and dielectric properties,were incorporated in this study.