Porous TiO2-coated Magnetic Core-Shell Nanocomposites：Preparation and Enhanced Photocatalytic Activity

The core-shell structured TiO2/SiO2 @Fe3O4 photocatalysts were prepared using Fe3O4 as magnetic core,tetraethoxysilane（TEOS） as silica source and tetrabutyl titanate（TBOT） as titanium sources.The as-obtained structure was composed of a SiO2@Fe3O4 core and a porous TiO2 shell.The diameter of SiO2@Fe3O4 core was about 205 nm with thickness of porous TiO2 of about 5-6 nm.The 9%TiO2/6%SiO2@Fe3O4 microspheres possess the highest BET surface area and the BJH pore volume,which are 373.5 m2.g-1 and 0.28 cm3.g-1,respectively.The 9%TiO2/6%SiO2@Fe3O4 photocatalyst exhibited an excellent performance for the degradation of methyl orange and methylene blue dyes.Two different dyes were completely decolorized in 60 min under UV irradiation.The photocatalytic activity and the amount of catalyst were almost not decrease after recycling for 6 times by using external magnetic field.

Oxidation behavior of porous Ti_3SiC_2 prepared by reactive synthesis

High-purity porous Ti3SiC2 with a porosity of 54.3%was prepared by reactive synthesis and its oxidation behavior was evaluated under air in the temperature range from 400 to 1000°C.Thermogravimetric analysis and differential scanning calorimetry(TG-DSC),scanning electron microscope(SEM),X-ray diffractometometry(XRD),energy dispersive spectrometer(EDS),Raman spectrum,BET surface area analysis,and pore-parameter testing were applied to the studies of the oxidation kinetics,phase composition,micro morphology,and porous structure parameters of porous Ti3SiC2 before and after oxidation.The results showed that the formation of TiO2 oxidized products with different modifications was the primary factor influencing the oxidation resistance and structural stability of porous Ti3SiC2.Cracks were observed in the samples oxidized in the full temperature range of 400-1000°C because of the growth stress and thermal stress.At 400-600°C,anomalous oxidation with higher kinetics and the aberrant decrement in pore size and permeability were attributed to the occurrence of severe cracking caused by the formation of anatase TiO2.At raised temperatures over 600°C,the cracking phenomena were alleviated by the formation of rutile TiO2,but the outward growth of the oxide scales detrimentally decreased the connectivity of porous Ti3SiC2.

Surface Microstructure Characterization of Sol-gel Derived Porous TiO_2 Thin Films

Porous TiO2 thin films were prepared from alkoxide solutions with and without polyethylene glycol (PEG) by sol-get route on soda lime glass, and were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that TiO2 film prepared from precursor solution without PEG is composed of spherical particles of about 100 nm and several nanometer mesoporous pores. With the increase of the amount of PEG added to the precursor solution, the diameter and the depth of the pores in the resultant films increas on the decomposition of PEG during heat-treatment, which lead to them increase of the surface roughness of the films. XRD and TEM results show that the single anatase phase is precipitated and there are some orientation effects in (101) direction.

Metal–organic framework derived hierarchical porous TiO_2 nanopills as a super stable anode for Na-ion batteries

Hierarchical porous TiOnanopills were synthesized using a titanium metal-organic framework MIL-125（Ti） as precursor. The as-synthesized TiOnanopills owned a large specific surface area of 102 m/g and unique porous structure. Furthermore, the obtained TiOnanopills were applied as anode materials for Na-ion batteries for the first time. The as-synthesized TiOnanopills achieved a high discharge capacity of 196.4 m Ah/g at a current density of 0.1 A/g. A discharge capacity of 115.9 m Ah/g was obtained at a high current density of 0.5 A/g and the capacity retention was remained as high as 90% even after 3000 cycles. The excellent electrochemical performance can be attributed to its unique hierarchical porous feature.

Preparation and Photocatalytic Property of Porous TiO_2 Film with Net-like Framework

By the UV-curing method, a porous TiO2 film with net-like framework has been prepared. The characterization results of the porous TiO2 film by means of SEM, TEM, XRD, and N2 adsorption-desorption analysis show that the net-like framework of the porous TiO2 film is composed of TiO2 nanoparticles, forming three dimensional porous structure. The porous TiO2 film exhibits higher photocatalytic activity for the degradation of methylene blue（MB） dye compared with the conventional dense TiO2 film.

Strengthening Porous PVA with TiO_2 Structure by an Ice-Templating Method

A poly vinyl alcohol（PVA） scaffold with aligned porous is strengthened by in-situ combining with TiO2. The increased freezing rate can be used to further increase the strength of aligned porous materials. The strengthened porous PVA exhibits aligned interconnected porous structures and shows a significant enhancement in tensile testing and compression strength testing.

Time-resolved Microwave Conductivity Studies on the Chemical Treatment of the Nanocrystalline Porous TiO2 Films

Effect of Ti(iso-C3H7O)4 treatment on the photoinduced charge carrier kinetics of nanocrystalline porous TiO2 films is studied by time-resolved microwave conductivity measurements. Analysis of the transient photoconductivity decays indicates that Ti(iso-C3H7O)4 treatment leads to an increased concentration of photogenerated charge carriers and a fast interfacial transfer rate of holes via the surface modification of the freshly growing TiO2 nanocrystallites.

Synthesis and Characterization of TiO₂Porous Films for Heterogeneous Photocatalysis

Heterogeneous photocatalysis is one of the advanced oxidation processes (AOP’s). These are very used nowadays for their implementation in tertiary water treatment with solar activation, with very good results. In this study, TiO2 porous films were synthesized by sol-gel method. Polyethylene glycol (PEG) 4000 was used as a templating reagent, which is oxidized at a lower temperature than TiO2. This allows the formation of a “skeleton” of porous TiO2 with increased surface area, resulting in higher photocatalytic activity. The film characterization was made with help of FE-SEM microscope, XRD diffractometer and scotch tape test. Finally, the oxidation experiments were performed using methylene blue as a model pollutant and they revealed an increase in the photocatalytic activity of porous films in comparison with the non-porous films.

Preparation and Characterization of Nanotitanium Dioxide Coating Film Doped with Fe^(3+) Ions on Porous Ceramic

The nanotitanium dioxide （TiO2） photocatalytic and porous ceramic filtering technique is one of the advanced methods to effectively treat organic wastewater. The TiO2 sol doped with Fe^3＋ ions was prepared by sol-gel processing. The influences of the process conditions of coating nanophotocatalytic material- Fe^3＋-TiO2 film on the surface of porous ceramic filter by dipping-lift method on the performance of porous ceramic filter were studied. The porous ceramic filters have two functions at the same time, filtration and photocatalytic degradation. The results of this study showed that the pH and viscosity of the sol, amount of Fe^3＋ ions doped as well as the coating times greatly affect the quality of coating film, the performance parameters and the photocatalytic activity of the porous ceramic filter. When the pH of the sol is 3-4, the viscosity is about 6 mPa.S, the amount of doped Fe^3＋ ions is about 2.0 g/L, the porous ceramic filter has been shown to have the best filtering performance and photocatalytic activity. In this condition, the porosity of porous ceramic is about 42.5%, the pore diameter is 8-10μm. The degradation of methyl-orange is 74.76% under lighting for 120 rain.

Preparation and Characterization of Nano-ZnFe_2O_4/TiO_2 Films

The nano-ZnFe2O4/TiO2 films possess the functions of desulfurization and degradation for organic pollutants. The sols of ZnFe2O4/TiO2 were prepared by sol-gel method and coated on glass and porous ceramic by vertical coating and dipping-lift processes, respectively, and the samples were obtained after drying and sintering. The composition, appearance, absorption spectrum of the films, and the influence of the film on porous ceramic performances were analyzed using SEM, AFM, UVVis spectrometer, and mercury porosimeter, respectively, to determine the operation parameters of the multifunction porous ceramic elements for gas-purification.

In-situ fabrication of dual porous titanium dioxide films as anode for carbon cathode based perovskite solar cell

We develop a dual porous （DP） TiO2 film for the electron transporting layer （ETL） in carbon cathode based perovskite solar cells （C-PSCs）. The DP TiO2 film was synthesized via a facile PS-templated method with the thickness being controlled by the spin-coating speed. It was found that there is an optimum DP TiO2 film thickness for achieving an effective ETL, a suitable perovskite]TiO2 interface, an efficient light harvester and thus a high performance C-PSC. In particular, such a DP TiO2 film can act as a scaffold for complete-filling of the pores with perovskite and for forming high-quality perovskite crystals that are seamlessly interfaced with Ti02 to enhance interracial charge injection. Leveraging the unique advantages of DP TiO2 ETL, together with a dense-packed and pinhole-free TiO2 compact layer, PCE of the C-PSCs has reached 9.81% with good stability.

Synergic effects of Cu_xO electron transfer co-catalyst and valence band edge control over TiO_2 for efficient visible-light photocatalysis

Bandgap engineering by doping and co‐catalyst loading are two primary approaches to designing efficient photocatalysts by promoting visible‐light absorption and charge separation,respectively.Shifting of the TiO2conduction band edge is frequently applied to increase visible‐light absorption but also lowers the reductive properties of photo‐excited electrons.Herein,we report a visible‐light‐driven photocatalyst based on valance band edge control induced by oxygen excess defects and modification with a CuxO electron transfer co‐catalyst.The CuxO grafted oxygen‐rich TiO2microspheres were prepared by ultrasonic spray pyrolysis of the peroxotitanate precursor followed by a wet chemical impregnated treatment.We found that oxygen excess defects in TiO2shifted the valence band maximum upward and improved the visible‐light absorption.The CuxO grafted onto the surface acted as a co‐catalyst that efficiently reduced oxygen molecules to active intermediates(i.e.,O2??radial and H2O2),thus consuming the photo‐generated electrons.Consequently,the CuxO grafted oxygen‐rich TiO2microspheres achieved a photocatalytic activity respectively8.6,13.0and11.0as times high as those of oxygen‐rich TiO2,normal TiO2and CuxO grafted TiO2,for degradation of gaseous acetaldehyde under visible‐light irradiation.Our results suggest that high visible‐light photocatalytic efficiency can be achieved by combining oxygen excess defects to improve visible‐light absorption together with a CuxO electron transfer co‐catalyst.These findings provide a new approach to developing efficient heterojunction photocatalysts.

Preparation of TiO2 and SiC Films from Their Precursors Using Electrospraying

Titanium dioxide(TiO2) films were prepared by cone - jet mode electrospraying a titanium ethoxideprecursor solution onto a silicon substrate.The effects of spraying time,substrate temperature and aging on thesurface morphology of the films prepared were studied.Thin films obtained after spraying for 600 s were aged atroom temperature to form a porous TiO2 network with pores in the size range of 100 - 500 nm.Thicker filmswere prepared by spraying for 3 000 s,but these cracked on drying although it can be concluded that films pre-pared using a higher substrate temperature were denser.By this method,SiC coating was also prepared on anAl2O3 substrate using polysilane as a precursor.The result implies the potential of an industrial production ofdye sensitized solar cells by electrospraying technique.

Preparation of defect free ceramic/Ti composite membranes by surface modification and in situ oxidation

Al2O3 ceramic powder was applied to modify the large pores defects on the surface of the porous metal Ti support,in situ oxidation method was a convenient method to prepare defect free ceramic/Ti composite membranes on this basis.In situ oxidation conditions experimental results show that the best condition for preparing the TiO2-Al2O3/Ti composite membrane is under 800°C for 2 h,and the microstructure and pore sizes of the TiO2-Al2O3/Ti composite membranes are affected obviously.The thickness and composition of the TiO2/Ti composite membranes are determined by SEM and XRD completely.The pore size distribution of the composite membrane is measured by bubble pressure method,the most probable aperture is about 3.12μm,while the average pore size of defect free TiO2-Al2O3/Ti is about 3.23μm.After ultrasonic treatment,the slight weight change of membranes reveals no observable change,which indicates that TiO2-Al2O3/Ti composite membranes maintain a good stability.

Optical and structural properties of highly porous shell structured Fe doped TiO_2 thin films

TiO2thin films with 0.2 wt%, 0.4 wt%, 0.6wt%, and 0.8 wt% Fe were prepared on glass and silicon substrates using sol–gel spin coating technique. The optical cut-off points are increasingly red-shifted and the absorption edge is shifted over the higher wavelength region with Fe content increasing. As Fe content increases, the optical band gap decreases from 3.03 to 2.48 eV whereas the tail width increases from 0.26 to 1.43 eV. The X-ray diffraction（XRD） patterns for doped films at 0.2 wt% and0.8 wt% Fe reveal no characteristic peaks, indicating that the film is amorphous whereas undoped TiO2exhibits（101） orientation with anatase phase. Thin films of higher Fe content exhibit a homogeneous, uniform, and nanostructured highly porous shell morphology.

In vitro and in vivo evaluation of porous NiTi alloy modified by sputtering a surface TiO_2 film

A uniform and dense TiO2 film was grown on the surface of porous NiTi shape memory alloys(SMAs) successfully by RF magnetron sputtering.The morphology and composition of the surface film were analyzed by using scanning electron microscopy and X-ray photoelectron spectroscopy.The corrosion resistance measurement proved that the surface modified porous NiTi SMAs exhibit better corrosion resistance and over 25% reduction of Ni ion release in the blood of the rabbits in comparing with the samples without surface modification.Moreover,the biocompatibility,as demonstrated by cell adherence and implant surgery,revealed that the cell adherence and bone tissue inducing capability are respectively enhanced over 1.1-1.2 and 9-10 times by sputtering a uniform TiO2 film on the surfaces of porous NiTi SMAs.

A Facile Synthesis of Hierarchically Porous TiO2 Microspheres with Carbonaceous Species for Visible-light Photocatalysis

Hierarchically porous anatase Ti02 microspheres composited with carbonaceous species （TCS） have been successfully fabricated by a one-step template-free solvothermal method, combined with subsequent low temperature dried process. In this configuration, the TCS microspheres are constructed by the intercon- nected porous nanosheets, which are further assembled with abundant nanoparticles and carbonaceous species. Such composite microspheres possess a large specific surface area of 337 m2 g-l, uniform mesopores of 3.37 nm and high total pore volumes of 0.275 cm3 g-1. The materials exhibit the enhanced photocatalytic properties and stability for degradation of rhodamine B （RhB） under visible-light irradiation. The enhanced photocatalytic degradation performance may be ascribed to their abundant porous structure, large specific surface area and the unique assist-function of the carbonaceous species.

Al2O3-TiO2/ZrO2-SiO2 based porous ceramics from particle-stabilized wet foam

The porous ceramics based on Al2O3-TiO2/ZrO2-SiO2 from particle-stabilized wet foam by direct foaming were discussed.The initial Al2O3-TiO2 suspension was prepared by adding TiO2 suspension to partially hydrophobized colloidal Al2O3 suspension with equimolar amount,to form Al2TiO5 on sintering.The secondary ZrO2-SiO2 suspension was prepared using the equimolar composition,and to obtain ZrSiO4,ZrTiO4,and mullite phases in the sintered samples,the secondary suspension was blended into the initial suspension at 0,10,20,30,and 50 vol％.The wet foam exhibited an air content up to 87％,Laplace pressure from 1.38 to 2.23 mPa,and higher adsorption free energy at the interface of approximately 5.8×108 to 7.5×108J resulting an outstanding foam stability of 87％.The final suspension was foamed,and the wet foam was sintered from 1400 to 1600 ℃ for 1 h.The porous ceramics with pore size from 150 to 400 μm on average were obtained.The phase identification was accomplished using X-ray diffraction (XRD),differential thermal analysis (DTA),and thermogravimetric analysis (TGA),and microstructural analysis was performed using field emission scanning electron microscopy (FESEM).

Aerosol Spray Pyrolysis Synthesis of Porous Anatase TiO_2 Microspheres with Tailored Photocatalytic Activity

Porous titanium dioxide(TiO_2) microspheres(MS) were prepared by a facile ultrasonic spray pyrolysis process with commercial colloidal silica as a sacrificial template. The morphology structure, Brunauer–Emmett–Teller surface areas and pore size distribution of TiO_2 microspheres were studied by changing the content and diameter of the silica template in detail. These porous micro-sized MS are composed of anatase TiO_2 nanocrystallites of 5–10 nm and have unique bimodal mesopores. The largest specific surface area of 112.3 m^2/g has been achieved using 60 wt% 20 nm silica as a template.When used as photocatalysts, the best photocatalytic activity of the as-prepared porous MS is comparable to commercial P25 nanopowders. Moreover, the micro-size and tailored properties from the design that appear during the ultrasonic spray pyrolysis process give these porous MS a promising application in photocatalytic reaction.

Synthesis of porous TiO2 nanowires and their photocatalytic properties

Porous titanium dioxide （ZiO2） nanowires were synthesized via a surfactant-free hydrothermal method followed by acid-washing process and calcination. The structures and morphologies of products were characterized by field emission scanning electron micro- scopy （FESEM）, Transmission electron microscopy （TEM）, X-ray diffraction （XRD）, and Brunauer-Emmett- Teller （BET） N2 adsorption-desorption analyses. The analysis of FESEM suggested the precursor was composed of a vast of uniform nanostructures like wires. The nanowire-like precursor was transformed into the porous nanowire after acid-treatment and calcination at 500~C for 2 h in air. The surface area of as-synthesized TiO2 nanowires calculated by BET is 86.4 m2/g. Furthermore, the photocatalytic properties of synthesized porous TiO2 nanowires were evaluated through the degradation of methylene blue （MB） and Rhodamine B （RhB）. The results clearly suggested that the as-prepared porous TiO2 nanowires showed remarkable photocatalytic performance on the degradation of RhB and MB due to their small size of nanocrystallites and the porous naonstructure.