Titanium dioxide (TiO<sub>2</sub>) doped with neodymium (Nd) and/or Gadolinium (Gd) rare-earth elements were fabricated into nanotubes via the hydrothermal method in a KOH solution and in-situ doping. Tita...Titanium dioxide (TiO<sub>2</sub>) doped with neodymium (Nd) and/or Gadolinium (Gd) rare-earth elements were fabricated into nanotubes via the hydrothermal method in a KOH solution and in-situ doping. Titanium dioxide nanotubes (TNTs) and in-situ Nd-doped and/or Gd-doped TNTs were characterized with transmission and scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Morphologies indicated a network of aggregated nanotubes. The phase and composition analyses revealed that the lanthanide TNTs had anatase phases with Nd and/or Gd nanoparticles in the TNT lattice. The nanoparticles were uniformly deposited on the surface because of hydroxyl groups on the TNT surfaces, resulting in a very high loading density. The outer diameter and the length of the TNTs increased with doping. The mechanisms for the formation of multiwall TNTs are discussed.展开更多
Au nanoparticle-decorated TiO2 nanotube arrays are prepared by a simple method, which is a thermal annealing thin gold film deposited on anodie oxidized TiO2 nanotube arrays. These electron microscope images present t...Au nanoparticle-decorated TiO2 nanotube arrays are prepared by a simple method, which is a thermal annealing thin gold film deposited on anodie oxidized TiO2 nanotube arrays. These electron microscope images present that Au nanoparticles are well dispersed within the wall and on the surface of the XiO2 nanotubes. Meanwhile, the morphologies of Au nanoparticles can be controlled by changing the thickness of the deposited gold film. Associ- ated with the excitation of localized surface plasmon resonances, the prepared Au nanoparticle-decorated TiO2 nanotube arrays could work as visible light responsive photocatalysts to produce a greatly enhanced photocurrent density. By varying the initial gold film thickness, such Au nanoparticle-decorated TiO2 nanotube arrays could be optimized to obtain the highest photocurrent generation efficiency in the visible and UV light regions.展开更多
Highly ordered TiO2 nanotube array (TNA) films are fabricated by using an anodic oxidation method. Au nanoparticles (NPs) films are decorated onto the top of TNA films with the aid of ion-sputtering and thermal an...Highly ordered TiO2 nanotube array (TNA) films are fabricated by using an anodic oxidation method. Au nanoparticles (NPs) films are decorated onto the top of TNA films with the aid of ion-sputtering and thermal annealing. An enhanced photocatalytic activity under ultraviolet C (UVC, 266 nm) light irradiation is obtained compared with that of the pristine TNA, which is shown by the steady-state photoluminescence (PL) spectra. Furthermore, a distinct blue shift in the nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra is observed. Such a phenomenon could be well explained by considering the competition between the surface photocatalytic process and the recombination of the photo-generated carriers. The enhanced UV photocatalytic activities of the Au-TNA composite are evaluated through photo-degradation of methyl orange (MO) in an aqueous solution with ultraviolet-visible absorption spectrometry. Our current work may provide a simple strategy to synthesize defect-related composite photocatalytic devices.展开更多
The efficiency of photo-electrocatalytic(PECa) devices for the production of solar fuels depends on several limiting factors such as light harvesting, charge recombination and mass transport diffusion. We analyse he...The efficiency of photo-electrocatalytic(PECa) devices for the production of solar fuels depends on several limiting factors such as light harvesting, charge recombination and mass transport diffusion. We analyse here how they influence the performances in PECa cells having a photo-anode based on Au-modified TiOnanotube(TNT) arrays, with the aim of developing design criteria to optimize the photo-anode and the PECa cell configuration for water photo-electrolysis(splitting) and ethanol photo-reforming processes.The TNT samples were prepared by controlled anodic oxidation of Ti foils and then decorated with gold nanoparticles using different techniques to enhance the visible light response through heterojunction and plasmonic effects. The activity tests were made in a gas-phase reactor, as well as in a PECa cell without applied bias. Results were analysed in terms of photo-generated current, Hproduction rate and photoconversion efficiency. Particularly, a solar-to-hydrogen efficiency of 0.83% and a Faradaic efficiency of 91%were obtained without adding sacrificial reagents.展开更多
TiO2 nanotube arrays (TNTs) electrode loaded with Zn nanoparticles was prepared by anodization and the size of Zn nanoparticle loaded on TNTs electrode was controlled by chronoamperometry deposition time. Results of...TiO2 nanotube arrays (TNTs) electrode loaded with Zn nanoparticles was prepared by anodization and the size of Zn nanoparticle loaded on TNTs electrode was controlled by chronoamperometry deposition time. Results of SEM and XRD analysis show that Zn nanoparticles had a diameter of about 15-25 nm when the deposition time was 3-5 s. The UV-Vis diffuse reflectance spectra show the Zn loaded harvest light with 480-780 nm more effectively than the unloaded sample. The photocurrent response of Zn loaded TNTs electrodes were studied, the results showed that TNTs electrodes loaded with Zn nanoparti-cles has 50% increased photocurrent response under high-pressure mercury lamp irradiation compared with unloaded TNTs electrode.展开更多
Vertically orientated TiO2 nanotube array with diameters ranging from 60 up to 80 nm and length of 4 μm was grown on titanium by anodization.Crack initiation,propagation and saturation were studied using the substrat...Vertically orientated TiO2 nanotube array with diameters ranging from 60 up to 80 nm and length of 4 μm was grown on titanium by anodization.Crack initiation,propagation and saturation were studied using the substrate straining test.The results show that annealing obviously modifies the interfaces.With the increase of tensile strain,cracks in TiO2 nanotube films propagate rapidly and reach the saturation within a narrow strain gap.Interfacial shear strengths of TiO2 nanotube films without annealing,with 250 ℃ annealing and with 400 ℃ annealing can be estimated as 163.3,370.2 and 684.5 MPa,respectively.The critical energy release rates of TiO2 nanotube films are calculated as 49.6,102.6 and 392.7 J/m2,respectively.The fracture toughnesses of TiO2 nanotube films are estimated as 0.996,1.433 and 2.803 MPa-m1/2,respectively.The interfacial bonding mechanism of TiO2 nanotube film is chemical bonding.展开更多
Substrate straining test was carried out to study the buckling pattern of TiO2 nanotube film. The results show that the tensile strains of buckling occurrence of TiO2 nanotube films without annealing, with 250 ℃ anne...Substrate straining test was carried out to study the buckling pattern of TiO2 nanotube film. The results show that the tensile strains of buckling occurrence of TiO2 nanotube films without annealing, with 250 ℃ annealing and with 400 ℃ annealing are 2.5%, 8.9% and 7.8%, respectively, which indicates the modifying effects of temperature annealing. Through the SEM observation, the critical buckling stresses of TiO2 nanotube films without annealing, with 250 ℃ annealing and with 400 ℃ annealing can be estimated as 180.4, 410.2 and 619.5 MPa, respectively. The critical buckling stress of TiO2 nanotube films with 250 ℃ annealing from AFM observation is estimated as 470.2 MPa, which indicates good agreement with the critical buckling stress from SEM observation. The true stress and the critical energy release rate of TiO2 nanotube film with 250 ℃ annealing are given as 840.3 MPa and 77.2 J/m2, respectively. Excellent agreement of the critical energy release rate of TiO2 nanotube film with 250 ℃ annealing in terms of buckling perspective and crack perspective is obtained.展开更多
A novel titanium dioxide (TiO2) film comprising both nanotubes and nanopaticles was fabricated by an anodization process of the modified titanium. The local electric field at the anodized surface was simulated and i...A novel titanium dioxide (TiO2) film comprising both nanotubes and nanopaticles was fabricated by an anodization process of the modified titanium. The local electric field at the anodized surface was simulated and its influence on the morphology of the TiO2 film was discussed. The results show that the electric field strength is enhanced by the covering. The growth rate of TiO2 increases with the assist of the local electric field. However, TiO2 dissolution is hindered since the local electric field prevents [TiF6]6- from diffusing. It means that the balance condition for the formation of nanotubes is broken, and TiO2 nanoparticles are formed. Moreover, the crystal structure of the TiO2 film was confirmed using X-ray diffraction and Raman analysis. The anatase is a main phase for the proposed film.展开更多
Curvature method was used to measure the residual stress and substrate straining tensile test was carried out to study the debonding behavior of TiO2 nanotube film. The results indicate that the internal residual stre...Curvature method was used to measure the residual stress and substrate straining tensile test was carried out to study the debonding behavior of TiO2 nanotube film. The results indicate that the internal residual stress is -54 MPa. The strains of debonding initiation of TiO2 nanotube films without annealing, with 250 °C annealing and with 400 °C annealing are 2.6%, 5.1% and 8.6%, respectively, and the average radii of the debonding patches with debonding initiation are 27.5, 17.1 and 19.4 μm, respectively. The true critical debonding stresses of TiO2 nanotube films without annealing, with 250 °C annealing and with 400 °C annealing can be estimated as 220.4, 394.5 and 627.9 MPa, respectively. Interfacial shear lag model is modified and polynomial fitting equation of the interfacial shear strength of TiO2 nanotube film is demonstrated under debonding conditions. The modification and polynomial fitting are reliable since good agreement of the interfacial shear strengths after fitting is obtained compared with those results from the crack density analysis.展开更多
A PbO2/Sb-SnO2/TiO2 nanotube array composite electrode was successfully synthesized and its electrochemical oxidation properties were investigated.Field-emission scanning electron microscopy(FE-SEM)and X-ray diffracti...A PbO2/Sb-SnO2/TiO2 nanotube array composite electrode was successfully synthesized and its electrochemical oxidation properties were investigated.Field-emission scanning electron microscopy(FE-SEM)and X-ray diffraction(XRD)results showed that the PbO2 coating was composed of anα-PbO2 inner layer and aβ-PbO2 outer layer.Accelerated life measurement indicated that the composite electrode had a lifetime of 815 h.Rhodamine B(RhB)was employed as a model pollutant to analyze the electrocatalytic activity of the electrode.The effects of initial RhB concentration,current density,initial pH,temperature,and chloride ion concentration on the electrochemical oxidation were investigated in detail.Inductively coupled plasma atomic emission spectroscopy(ICP-AES)results suggested that the concentration of leached Pb^2+in the electrolyte during the electrocatalytic oxidation process can be neglected.Finally,the degradation mechanism during the electrocatalytic oxidation process was proposed based on the results of solid-phase micro-extraction-gas chromatography-mass spectrometry(SPME-GC-MS).The high electrocatalytic performance of the composite electrode makes it a promising anode for the treatment of organic pollutants in aqueous solution.展开更多
Two-dimensional (2D) ultrathin MoS2-modified black Ti^3+-TiO2 nanotubes were fabricated using an electrospinning-hydrothermal treatment-reduction method.Bare TiO2 nanotubes were fabricated via electrospinning.Then,2D ...Two-dimensional (2D) ultrathin MoS2-modified black Ti^3+-TiO2 nanotubes were fabricated using an electrospinning-hydrothermal treatment-reduction method.Bare TiO2 nanotubes were fabricated via electrospinning.Then,2D MoS2 lamellae were grown on the surface of the nanotubes and Ti^3+/Ov ions were introduced by reduction.The photocatalytic performance of the 2D MoS2/Ti^3+-TiO2 nanotubes was^15 times better than that of TiO2.The HER enhancement of the MoS2/Ti^3+-TiO2 nanotubes can be attributed to the Pt-like behavior of 2D MoS2 and the presence of Ti^3+-ions,which facilitated the quick diffusion of the photogenerated electrons to water,reducing the H2 activation barrier.The presence of Ov ions in the nanotubes and their hollow structure increased their solar utilization.展开更多
The process, that the polycrystalline TiO2 powders were converted into TiO2 nanotubes, was observed with transmission electron microscope. The results obtained indicated that in concentrated NaOH aqueous solution, an...The process, that the polycrystalline TiO2 powders were converted into TiO2 nanotubes, was observed with transmission electron microscope. The results obtained indicated that in concentrated NaOH aqueous solution, anisotropic swelling appears on the polycrystalline TiO2 granula at first, and then the nanotubes are formed.展开更多
TiO2 nanotube precursor was synthesized by the hydrothermal reaction of TiO2 powders with NaOH solution and the properties of the nanotube materials were tuned using different post-treatments. Transmission electron mi...TiO2 nanotube precursor was synthesized by the hydrothermal reaction of TiO2 powders with NaOH solution and the properties of the nanotube materials were tuned using different post-treatments. Transmission electron microscopic (TEM) observation revealed that the nanotube could be obtained by either a direct rinse with acid solution or rinse with distilled water followed by acid solution. The results of X-ray diffraction (XRD) and inductively coupled plasma (ICP) analysis indicated that the nanotube material was composed of H2Ti2O5·H2O. In addition, the photocatalytic activities of the resulting catalysts were found to be strongly dependent on the post-treatment. The results of the photocatalytic reaction showed that the degradation of Acid-red 3B dye fitted pseudo-zero-order kinetics and TiO2 nanotube prepared under direct rinse with acid solution exhibited a higher catalytic efficiency compared to other catalysts.展开更多
We report the development of a novel visible response BiVO_4/TiO_2(N_2) nanotubes photoanode for photoelectrocatalytic applications. The nitrogen-treated TiO_2 nanotube shows a high carrier concentration rate, thus re...We report the development of a novel visible response BiVO_4/TiO_2(N_2) nanotubes photoanode for photoelectrocatalytic applications. The nitrogen-treated TiO_2 nanotube shows a high carrier concentration rate, thus resulting in a high efficient charge transportation and low electron–hole recombination in the TiO_2–BiVO_4. Therefore, the BiVO_4/TiO_2(N_2) NTs photoanode enabled with a significantly enhanced photocurrent of 2.73 mA cm^(-2)(at 1 V vs. Ag/Ag Cl) and a degradation efficiency in the oxidation of dyes under visible light. Field emission scanning electron microscopy, X-ray diffractometry, energy-dispersive X-ray spectrometer, and UV–Vis absorption spectrum were conducted to characterize the photoanode and demonstrated the presence of both metal oxides as a junction composite.展开更多
Copper and titanium remain relatively plentiful in earth crust.Therefore,using them in solar energy conversion technologies are of significant interest.In this work,cuprous oxide(Cu2O)-modified short TiO2 nanotube a...Copper and titanium remain relatively plentiful in earth crust.Therefore,using them in solar energy conversion technologies are of significant interest.In this work,cuprous oxide(Cu2O)-modified short TiO2 nanotube array electrode was prepared based on the following two design ideas:first,the short titania nanotubes obtained from sonoelectrochemical anodization possess excellent charge separation and transportation properties as well as desirable mechanical stability;second,the sonoelectrochemical deposition technique favours the improvement in the combination between Cu2O and TiO2 nanotubes,and favours the dispersion of Cu2O particles.UV-Vis absorption and photo-electronchemical measurements proved that the Cu2O coating extended the visible spectrum absorption and the solar spectrum-induced photocurrent response.Under AM1.5 irradiation,the photocurrent density of the composite electrode(i.e.sonoelectrochemical deposition for 5 min) was more than 4.75 times as high as the pure nanotube electrode.Comparing the photoactivity of the Cu2O/TiO2 electrode obtained using sonoelectrochemical deposition with others that synthesized using plain electrochemical deposition,the photocurrent density of the former electrode was 2.2 times higher than that of the latter when biased at 1.0 V(vs.Ag/AgCl).The reproducible photocurrent response under intermittent illumination demonstrated the excellent stability of the composite electrode.Such kind of composite electrode material will have many potential applications in solar cell and other fields.展开更多
IrO2 and IrRuOx(Ir:Ru 60:40 at%),supported by 50 wt%onto titania nanotubes(TNTs)and(3 at%Nb)Nb-doped titania nanotubes(Nb-TNTs),as electrocatalysts for the oxygen evolution reaction(OER),were synthesized and character...IrO2 and IrRuOx(Ir:Ru 60:40 at%),supported by 50 wt%onto titania nanotubes(TNTs)and(3 at%Nb)Nb-doped titania nanotubes(Nb-TNTs),as electrocatalysts for the oxygen evolution reaction(OER),were synthesized and characterized by means of structural,surface analytical and electrochemical techniques.Nb doping of titania significantly increased the surface area of the support from 145(TNTs)to 260 m2g-1(Nb-TNTs),which was significantly higher than those of the Nb-doped titania supports previously reported in the literature.The surface analytical techniques showed good dispersion of the catalysts onto the supports.The X-ray photoelectron spectroscopy analyses showed that Nb was mainly in the form of Nb(IV)species,the suitable form to behave as a donor introducing free electrons to the conduction band of titania.The redox transitions of the cyclic voltammograms,in agreement with the XPS results,were found to be reversible.Despite the supported materials presented bigger crystallite sizes than the unsupported ones,the total number of active sites of the former was also higher due to their better catalyst dispersion.Considering the outer and the total charges of the cyclic voltammograms in the range 0.1–1.4 V,stability and electrode potentials at given current densities,the preferred catalyst was Ir O2 supported on the Nb-TNTs.The electrode potentials corresponding to given current densities were between the smallest ones given in the literature despite the small oxide loading used in this work and its Nb doping,thus making the Nb-TNTs-supported IrO2 catalyst a promising candidate for the OER.The good dispersion of IrO2,high specific surface area of the Nb-doped supports,accessibility of the electroactive centers,increased stability due to Nb doping and electron donor properties of the Nb(IV)oxide species were considered the main reasons for its good performance.展开更多
Polyaniline (PANI) composite nanotubes (90-130 nm in diameter) containing titanium dioxide (TiO2) nanoparticles (about 10 nm in diameter) were synthesized through a self-assembly process in the presence of a-n...Polyaniline (PANI) composite nanotubes (90-130 nm in diameter) containing titanium dioxide (TiO2) nanoparticles (about 10 nm in diameter) were synthesized through a self-assembly process in the presence of a-naphthalenesulfonic acid (a-NSA) as the dopant. It was found that PANI-TiO2 composites and PANI nanotubes both behaved with significant photocatalytic activities towards AZO dyes, during 2 h photocatalytic processes under natural light, the degradation ratio was 94.2% and 97.2% respectively (methyl orange and orange II). The morphology of such products was characterized by SEM. The specific surface area of such composite nanotubes was 14.7 m2/g compared to normal polyaniline which was 0.27 m2/g. IR and X-ray diffraction characterizations showed that the chemical chain of the composite nanotubes was identical to that of the doped PANI. It may provide a new way for photodegradation of organic contaminants by using conjugated polymer with dimensional structure.展开更多
Well-ordered TiO_2 nanotube arrays(TNTAs)decorated with graphitic carbon nitride(g-C_3N_4) were fabricated by anodic oxidization and calcination process.First, TNTAs were prepared via the anodic oxidation of Ti foil i...Well-ordered TiO_2 nanotube arrays(TNTAs)decorated with graphitic carbon nitride(g-C_3N_4) were fabricated by anodic oxidization and calcination process.First, TNTAs were prepared via the anodic oxidation of Ti foil in glycerol solution containing fluorinion and 20%deionized water. Subsequently, g-C_3N_4 film was hydrothermally grown on TNTAs via the hydrogen-bonded cyanuric acid melamine supramolecular complex. The results showed that g-C_3N_4 was successfully decorated on the TNTAs and the g-C_3N_4/TNTAs served as an efficient and stable photoanode for photoelectrochemical water splitting. The facile deposition method enables the fabrication of efficient and low-cost photoanodes for renewable energy applications.展开更多
We report a colloidal process to coat a layer of TiO2onto SiO2composite nanofibers containing embedded CdS and upconversion nanoparticles(UCNPs).The SiO2composite nanofibers were fabricated by electrospinning.To impro...We report a colloidal process to coat a layer of TiO2onto SiO2composite nanofibers containing embedded CdS and upconversion nanoparticles(UCNPs).The SiO2composite nanofibers were fabricated by electrospinning.To improve the energy transfer efficiency,UCNPs and CdS nanoparticles were bound in close proximity to each other within the SiO2matrix.β‐NaYF4:Yb(30%),Tm(0.5%)@NaYF4:Yb(20%),Er(2%)core–shell nanoparticles were used as nanotransducers for near infrared light.These nanoparticles exhibited enhanced upconversion fluorescence compared withβ‐NaYF4:Yb(30%),Tm(0.5%)orβ–NaYF4:Yb(30%),Tm(0.5%)@NaYF4nanoparticles.The morphologies,size and chemical compositions have been extensively investigated using field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),X‐ray diffraction(XRD)and X‐ray photoelectron spectra(XPS),respectively.The TEM images showed that the TiO2composite nanotubes were embedded with a large amount of UCNPs and CdS nanoparticles.The composite TiO2nanotubes degraded more than90%of rhodamine B(RhB)dye during20min of irradiation by simulated solar light.In particular,more than50%of RhB was decomposed in70min,under irradiation of near infrared light(NIR).This high degradation was attributed to the full spectrum absorption of solar light,and the enhanced transfer efficiency for near infrared light.The as‐prepared nanostructures can harness solar energy,and provide an alternative to overcome energy shortages and environmental protection.展开更多
文摘Titanium dioxide (TiO<sub>2</sub>) doped with neodymium (Nd) and/or Gadolinium (Gd) rare-earth elements were fabricated into nanotubes via the hydrothermal method in a KOH solution and in-situ doping. Titanium dioxide nanotubes (TNTs) and in-situ Nd-doped and/or Gd-doped TNTs were characterized with transmission and scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, Raman spectroscopy, and Fourier-transform infrared spectroscopy. Morphologies indicated a network of aggregated nanotubes. The phase and composition analyses revealed that the lanthanide TNTs had anatase phases with Nd and/or Gd nanoparticles in the TNT lattice. The nanoparticles were uniformly deposited on the surface because of hydroxyl groups on the TNT surfaces, resulting in a very high loading density. The outer diameter and the length of the TNTs increased with doping. The mechanisms for the formation of multiwall TNTs are discussed.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11474215 and 21204058the Priority Academic Program Development of Jiangsu Higher Education Institutions
文摘Au nanoparticle-decorated TiO2 nanotube arrays are prepared by a simple method, which is a thermal annealing thin gold film deposited on anodie oxidized TiO2 nanotube arrays. These electron microscope images present that Au nanoparticles are well dispersed within the wall and on the surface of the XiO2 nanotubes. Meanwhile, the morphologies of Au nanoparticles can be controlled by changing the thickness of the deposited gold film. Associ- ated with the excitation of localized surface plasmon resonances, the prepared Au nanoparticle-decorated TiO2 nanotube arrays could work as visible light responsive photocatalysts to produce a greatly enhanced photocurrent density. By varying the initial gold film thickness, such Au nanoparticle-decorated TiO2 nanotube arrays could be optimized to obtain the highest photocurrent generation efficiency in the visible and UV light regions.
基金supported by the National Natural Science Foundation of China(Grant No.11274082)the Shandong Excellent Young Scientist Research Award Fund Project,China(Grant No.BS2011CL002)
文摘Highly ordered TiO2 nanotube array (TNA) films are fabricated by using an anodic oxidation method. Au nanoparticles (NPs) films are decorated onto the top of TNA films with the aid of ion-sputtering and thermal annealing. An enhanced photocatalytic activity under ultraviolet C (UVC, 266 nm) light irradiation is obtained compared with that of the pristine TNA, which is shown by the steady-state photoluminescence (PL) spectra. Furthermore, a distinct blue shift in the nanosecond time-resolved transient photoluminescence (NTRT-PL) spectra is observed. Such a phenomenon could be well explained by considering the competition between the surface photocatalytic process and the recombination of the photo-generated carriers. The enhanced UV photocatalytic activities of the Au-TNA composite are evaluated through photo-degradation of methyl orange (MO) in an aqueous solution with ultraviolet-visible absorption spectrometry. Our current work may provide a simple strategy to synthesize defect-related composite photocatalytic devices.
基金The TERRA(Tandem Electrocatalytic Reactor for energy/Resource efficiency and process intensification,H2020 project 677471)Eco~2CO_2(Eco-friendly biorefinery fine chemicals from CO_2 photo-catalytic reduction,FP7 project 309701)
文摘The efficiency of photo-electrocatalytic(PECa) devices for the production of solar fuels depends on several limiting factors such as light harvesting, charge recombination and mass transport diffusion. We analyse here how they influence the performances in PECa cells having a photo-anode based on Au-modified TiOnanotube(TNT) arrays, with the aim of developing design criteria to optimize the photo-anode and the PECa cell configuration for water photo-electrolysis(splitting) and ethanol photo-reforming processes.The TNT samples were prepared by controlled anodic oxidation of Ti foils and then decorated with gold nanoparticles using different techniques to enhance the visible light response through heterojunction and plasmonic effects. The activity tests were made in a gas-phase reactor, as well as in a PECa cell without applied bias. Results were analysed in terms of photo-generated current, Hproduction rate and photoconversion efficiency. Particularly, a solar-to-hydrogen efficiency of 0.83% and a Faradaic efficiency of 91%were obtained without adding sacrificial reagents.
基金ACKNOWLEDGMENTS This work was supported by the Science Foundation of Chongqing Science and Technology Committee (No.CSTS2009BB4047), and Innovative Talent Training Project, the Third Stage of "211 Project" of Chongqing University (No.S-09109).
文摘TiO2 nanotube arrays (TNTs) electrode loaded with Zn nanoparticles was prepared by anodization and the size of Zn nanoparticle loaded on TNTs electrode was controlled by chronoamperometry deposition time. Results of SEM and XRD analysis show that Zn nanoparticles had a diameter of about 15-25 nm when the deposition time was 3-5 s. The UV-Vis diffuse reflectance spectra show the Zn loaded harvest light with 480-780 nm more effectively than the unloaded sample. The photocurrent response of Zn loaded TNTs electrodes were studied, the results showed that TNTs electrodes loaded with Zn nanoparti-cles has 50% increased photocurrent response under high-pressure mercury lamp irradiation compared with unloaded TNTs electrode.
基金Project(50604017) supported by the National Natural Science Foundation of ChinaProject(20110946Z) supported by the State Key Laboratory of Powder Metallurgy,China
文摘Vertically orientated TiO2 nanotube array with diameters ranging from 60 up to 80 nm and length of 4 μm was grown on titanium by anodization.Crack initiation,propagation and saturation were studied using the substrate straining test.The results show that annealing obviously modifies the interfaces.With the increase of tensile strain,cracks in TiO2 nanotube films propagate rapidly and reach the saturation within a narrow strain gap.Interfacial shear strengths of TiO2 nanotube films without annealing,with 250 ℃ annealing and with 400 ℃ annealing can be estimated as 163.3,370.2 and 684.5 MPa,respectively.The critical energy release rates of TiO2 nanotube films are calculated as 49.6,102.6 and 392.7 J/m2,respectively.The fracture toughnesses of TiO2 nanotube films are estimated as 0.996,1.433 and 2.803 MPa-m1/2,respectively.The interfacial bonding mechanism of TiO2 nanotube film is chemical bonding.
基金Project (51274248) supported by the National Natural Science Foundation of ChinaProject (20110946Z) supported by State Key Laboratory of Powder Metallurgy, China
文摘Substrate straining test was carried out to study the buckling pattern of TiO2 nanotube film. The results show that the tensile strains of buckling occurrence of TiO2 nanotube films without annealing, with 250 ℃ annealing and with 400 ℃ annealing are 2.5%, 8.9% and 7.8%, respectively, which indicates the modifying effects of temperature annealing. Through the SEM observation, the critical buckling stresses of TiO2 nanotube films without annealing, with 250 ℃ annealing and with 400 ℃ annealing can be estimated as 180.4, 410.2 and 619.5 MPa, respectively. The critical buckling stress of TiO2 nanotube films with 250 ℃ annealing from AFM observation is estimated as 470.2 MPa, which indicates good agreement with the critical buckling stress from SEM observation. The true stress and the critical energy release rate of TiO2 nanotube film with 250 ℃ annealing are given as 840.3 MPa and 77.2 J/m2, respectively. Excellent agreement of the critical energy release rate of TiO2 nanotube film with 250 ℃ annealing in terms of buckling perspective and crack perspective is obtained.
文摘A novel titanium dioxide (TiO2) film comprising both nanotubes and nanopaticles was fabricated by an anodization process of the modified titanium. The local electric field at the anodized surface was simulated and its influence on the morphology of the TiO2 film was discussed. The results show that the electric field strength is enhanced by the covering. The growth rate of TiO2 increases with the assist of the local electric field. However, TiO2 dissolution is hindered since the local electric field prevents [TiF6]6- from diffusing. It means that the balance condition for the formation of nanotubes is broken, and TiO2 nanoparticles are formed. Moreover, the crystal structure of the TiO2 film was confirmed using X-ray diffraction and Raman analysis. The anatase is a main phase for the proposed film.
基金Project (51274248) supported by the National Natural Science Foundation of ChinaProject (20110946Z) supported by the State Key Laboratory of Powder Metallurgy, China
文摘Curvature method was used to measure the residual stress and substrate straining tensile test was carried out to study the debonding behavior of TiO2 nanotube film. The results indicate that the internal residual stress is -54 MPa. The strains of debonding initiation of TiO2 nanotube films without annealing, with 250 °C annealing and with 400 °C annealing are 2.6%, 5.1% and 8.6%, respectively, and the average radii of the debonding patches with debonding initiation are 27.5, 17.1 and 19.4 μm, respectively. The true critical debonding stresses of TiO2 nanotube films without annealing, with 250 °C annealing and with 400 °C annealing can be estimated as 220.4, 394.5 and 627.9 MPa, respectively. Interfacial shear lag model is modified and polynomial fitting equation of the interfacial shear strength of TiO2 nanotube film is demonstrated under debonding conditions. The modification and polynomial fitting are reliable since good agreement of the interfacial shear strengths after fitting is obtained compared with those results from the crack density analysis.
基金supported by the National Natural Science Foundation of China(21507104)Natural Science Basic Research Plan in Shaanxi Province of China(2017JM2015)~~
文摘A PbO2/Sb-SnO2/TiO2 nanotube array composite electrode was successfully synthesized and its electrochemical oxidation properties were investigated.Field-emission scanning electron microscopy(FE-SEM)and X-ray diffraction(XRD)results showed that the PbO2 coating was composed of anα-PbO2 inner layer and aβ-PbO2 outer layer.Accelerated life measurement indicated that the composite electrode had a lifetime of 815 h.Rhodamine B(RhB)was employed as a model pollutant to analyze the electrocatalytic activity of the electrode.The effects of initial RhB concentration,current density,initial pH,temperature,and chloride ion concentration on the electrochemical oxidation were investigated in detail.Inductively coupled plasma atomic emission spectroscopy(ICP-AES)results suggested that the concentration of leached Pb^2+in the electrolyte during the electrocatalytic oxidation process can be neglected.Finally,the degradation mechanism during the electrocatalytic oxidation process was proposed based on the results of solid-phase micro-extraction-gas chromatography-mass spectrometry(SPME-GC-MS).The high electrocatalytic performance of the composite electrode makes it a promising anode for the treatment of organic pollutants in aqueous solution.
基金supported by the National Natural Science Foundation of China(Grant Nos.51672249,51802282,and 11804301)the Zhejiang Provincial Natural Science Foundation of China(Grant Nos.LQ17F040004 and LY17E020001)Fundamental Research Funds of Zhejiang Sci-Tech University(No.2019Q062)。
文摘Two-dimensional (2D) ultrathin MoS2-modified black Ti^3+-TiO2 nanotubes were fabricated using an electrospinning-hydrothermal treatment-reduction method.Bare TiO2 nanotubes were fabricated via electrospinning.Then,2D MoS2 lamellae were grown on the surface of the nanotubes and Ti^3+/Ov ions were introduced by reduction.The photocatalytic performance of the 2D MoS2/Ti^3+-TiO2 nanotubes was^15 times better than that of TiO2.The HER enhancement of the MoS2/Ti^3+-TiO2 nanotubes can be attributed to the Pt-like behavior of 2D MoS2 and the presence of Ti^3+-ions,which facilitated the quick diffusion of the photogenerated electrons to water,reducing the H2 activation barrier.The presence of Ov ions in the nanotubes and their hollow structure increased their solar utilization.
基金This project was supported by the National Natural Science Foundation of China (20071010).
文摘The process, that the polycrystalline TiO2 powders were converted into TiO2 nanotubes, was observed with transmission electron microscope. The results obtained indicated that in concentrated NaOH aqueous solution, anisotropic swelling appears on the polycrystalline TiO2 granula at first, and then the nanotubes are formed.
文摘TiO2 nanotube precursor was synthesized by the hydrothermal reaction of TiO2 powders with NaOH solution and the properties of the nanotube materials were tuned using different post-treatments. Transmission electron microscopic (TEM) observation revealed that the nanotube could be obtained by either a direct rinse with acid solution or rinse with distilled water followed by acid solution. The results of X-ray diffraction (XRD) and inductively coupled plasma (ICP) analysis indicated that the nanotube material was composed of H2Ti2O5·H2O. In addition, the photocatalytic activities of the resulting catalysts were found to be strongly dependent on the post-treatment. The results of the photocatalytic reaction showed that the degradation of Acid-red 3B dye fitted pseudo-zero-order kinetics and TiO2 nanotube prepared under direct rinse with acid solution exhibited a higher catalytic efficiency compared to other catalysts.
基金the National Nature Science Foundation of China(21507085,21576162)Shanghai Sailing Program of China(14YF1401500)for financial support
文摘We report the development of a novel visible response BiVO_4/TiO_2(N_2) nanotubes photoanode for photoelectrocatalytic applications. The nitrogen-treated TiO_2 nanotube shows a high carrier concentration rate, thus resulting in a high efficient charge transportation and low electron–hole recombination in the TiO_2–BiVO_4. Therefore, the BiVO_4/TiO_2(N_2) NTs photoanode enabled with a significantly enhanced photocurrent of 2.73 mA cm^(-2)(at 1 V vs. Ag/Ag Cl) and a degradation efficiency in the oxidation of dyes under visible light. Field emission scanning electron microscopy, X-ray diffractometry, energy-dispersive X-ray spectrometer, and UV–Vis absorption spectrum were conducted to characterize the photoanode and demonstrated the presence of both metal oxides as a junction composite.
基金the State Key Development Program for Basic Research of China (Grant No.2009CB220004)the Shanghai Basic Research Key Project (08JC1411300,0952nm01800)+1 种基金the National High Technology Research and Development Program of China (Grant No.2009 AA063003)Shanghai Tongji Gao Tingyao Environmental Science and Technology Development Foundation for financial support
文摘Copper and titanium remain relatively plentiful in earth crust.Therefore,using them in solar energy conversion technologies are of significant interest.In this work,cuprous oxide(Cu2O)-modified short TiO2 nanotube array electrode was prepared based on the following two design ideas:first,the short titania nanotubes obtained from sonoelectrochemical anodization possess excellent charge separation and transportation properties as well as desirable mechanical stability;second,the sonoelectrochemical deposition technique favours the improvement in the combination between Cu2O and TiO2 nanotubes,and favours the dispersion of Cu2O particles.UV-Vis absorption and photo-electronchemical measurements proved that the Cu2O coating extended the visible spectrum absorption and the solar spectrum-induced photocurrent response.Under AM1.5 irradiation,the photocurrent density of the composite electrode(i.e.sonoelectrochemical deposition for 5 min) was more than 4.75 times as high as the pure nanotube electrode.Comparing the photoactivity of the Cu2O/TiO2 electrode obtained using sonoelectrochemical deposition with others that synthesized using plain electrochemical deposition,the photocurrent density of the former electrode was 2.2 times higher than that of the latter when biased at 1.0 V(vs.Ag/AgCl).The reproducible photocurrent response under intermittent illumination demonstrated the excellent stability of the composite electrode.Such kind of composite electrode material will have many potential applications in solar cell and other fields.
文摘IrO2 and IrRuOx(Ir:Ru 60:40 at%),supported by 50 wt%onto titania nanotubes(TNTs)and(3 at%Nb)Nb-doped titania nanotubes(Nb-TNTs),as electrocatalysts for the oxygen evolution reaction(OER),were synthesized and characterized by means of structural,surface analytical and electrochemical techniques.Nb doping of titania significantly increased the surface area of the support from 145(TNTs)to 260 m2g-1(Nb-TNTs),which was significantly higher than those of the Nb-doped titania supports previously reported in the literature.The surface analytical techniques showed good dispersion of the catalysts onto the supports.The X-ray photoelectron spectroscopy analyses showed that Nb was mainly in the form of Nb(IV)species,the suitable form to behave as a donor introducing free electrons to the conduction band of titania.The redox transitions of the cyclic voltammograms,in agreement with the XPS results,were found to be reversible.Despite the supported materials presented bigger crystallite sizes than the unsupported ones,the total number of active sites of the former was also higher due to their better catalyst dispersion.Considering the outer and the total charges of the cyclic voltammograms in the range 0.1–1.4 V,stability and electrode potentials at given current densities,the preferred catalyst was Ir O2 supported on the Nb-TNTs.The electrode potentials corresponding to given current densities were between the smallest ones given in the literature despite the small oxide loading used in this work and its Nb doping,thus making the Nb-TNTs-supported IrO2 catalyst a promising candidate for the OER.The good dispersion of IrO2,high specific surface area of the Nb-doped supports,accessibility of the electroactive centers,increased stability due to Nb doping and electron donor properties of the Nb(IV)oxide species were considered the main reasons for its good performance.
基金Funded in Part by the Research Fund of Hubei Provincial Department of Education,China(No.Q20121102)
文摘Polyaniline (PANI) composite nanotubes (90-130 nm in diameter) containing titanium dioxide (TiO2) nanoparticles (about 10 nm in diameter) were synthesized through a self-assembly process in the presence of a-naphthalenesulfonic acid (a-NSA) as the dopant. It was found that PANI-TiO2 composites and PANI nanotubes both behaved with significant photocatalytic activities towards AZO dyes, during 2 h photocatalytic processes under natural light, the degradation ratio was 94.2% and 97.2% respectively (methyl orange and orange II). The morphology of such products was characterized by SEM. The specific surface area of such composite nanotubes was 14.7 m2/g compared to normal polyaniline which was 0.27 m2/g. IR and X-ray diffraction characterizations showed that the chemical chain of the composite nanotubes was identical to that of the doped PANI. It may provide a new way for photodegradation of organic contaminants by using conjugated polymer with dimensional structure.
基金financial support from the National Natural Science Foundation of China (Nos. 51702025, 51574047)Natural Science Foundation of Jiangsu Province (Nos. BK20160277, BK20150259)
文摘Well-ordered TiO_2 nanotube arrays(TNTAs)decorated with graphitic carbon nitride(g-C_3N_4) were fabricated by anodic oxidization and calcination process.First, TNTAs were prepared via the anodic oxidation of Ti foil in glycerol solution containing fluorinion and 20%deionized water. Subsequently, g-C_3N_4 film was hydrothermally grown on TNTAs via the hydrogen-bonded cyanuric acid melamine supramolecular complex. The results showed that g-C_3N_4 was successfully decorated on the TNTAs and the g-C_3N_4/TNTAs served as an efficient and stable photoanode for photoelectrochemical water splitting. The facile deposition method enables the fabrication of efficient and low-cost photoanodes for renewable energy applications.
基金supported in part by the National Natural Science Foundation of China(21471043,21304028,51403195,31501576)~~
文摘We report a colloidal process to coat a layer of TiO2onto SiO2composite nanofibers containing embedded CdS and upconversion nanoparticles(UCNPs).The SiO2composite nanofibers were fabricated by electrospinning.To improve the energy transfer efficiency,UCNPs and CdS nanoparticles were bound in close proximity to each other within the SiO2matrix.β‐NaYF4:Yb(30%),Tm(0.5%)@NaYF4:Yb(20%),Er(2%)core–shell nanoparticles were used as nanotransducers for near infrared light.These nanoparticles exhibited enhanced upconversion fluorescence compared withβ‐NaYF4:Yb(30%),Tm(0.5%)orβ–NaYF4:Yb(30%),Tm(0.5%)@NaYF4nanoparticles.The morphologies,size and chemical compositions have been extensively investigated using field emission scanning electron microscopy(FESEM),transmission electron microscopy(TEM),X‐ray diffraction(XRD)and X‐ray photoelectron spectra(XPS),respectively.The TEM images showed that the TiO2composite nanotubes were embedded with a large amount of UCNPs and CdS nanoparticles.The composite TiO2nanotubes degraded more than90%of rhodamine B(RhB)dye during20min of irradiation by simulated solar light.In particular,more than50%of RhB was decomposed in70min,under irradiation of near infrared light(NIR).This high degradation was attributed to the full spectrum absorption of solar light,and the enhanced transfer efficiency for near infrared light.The as‐prepared nanostructures can harness solar energy,and provide an alternative to overcome energy shortages and environmental protection.