Surface Of TiO2 NTs Research Articles

Enhancing photoelectrochemical performance of TiO2 nanotube arrays by CdS and Bi2S3 co-sensitization

TiO2 nanotube arrays (TiO2 NTs) were prepared by a two-step anodization of titanium foils in ethylene glycol electrolyte. Then, CdS and Bi2S3 nanoparticles were deposited on TiO2 NTs by an one-pot solvothermal method. The investigations of X-ray diffraction and scanning electron microscopy indicated that CdS and Bi2S3 nanoparticles grew uniformly on the surface of TiO2 NTs. UV–vis absorption and photoelectrochemical measurements proved that the CdS and Bi2S3 co-sensitization significantly improved the visible light absorption, photocurrent response and photoelectrocatalytic removal of RhB and Cr(VI). In addition, the influence of Cd2+/Bi3+ concentration ratios on the photoelectrochemical performance of TiO2 NTs-CdS/Bi2S3 was investigated in detail. The TiO2 NTs-CdS/Bi2S3 (1:1) showed an optimal photoelectrochemical activity which could be attributed to the improvement of visible light response and charge separation derived from the coupling effect of CdS/Bi2S3 nanoparticles.

Photodeposition of CdS Nanoparticles Sensitized TiO2 Nanotube Arrays for Enhanced Photoelectrochemical Performance

The heteronanojunction CdS/TiO2 nanotube arrays (TiO2 NTs/CdS) were prepared by coating CdS nanoparticles on the tube wall of the self-organized TiO2 NTs using a novel photodeposition method. The adsorption of CdS nanoparticles on the upper and inner surface of TiO2 NTs was confirmed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, and the corresponding formation mechanism of the TiO2 NTs/CdS was tentatively proposed. The TiO2 NTs/CdS exhibited higher photoelectrochemical properties and photocatalytic activities than those of TiO2 NTs under visible light irradiation.

Uniformly dispersed CdS nanoparticles sensitized TiO2 nanotube arrays with enhanced visible-light photocatalytic activity and stability

In this study, TiO2 nanotube arrays (TiO2-NTs) with various intertube spaces were fabricated in the electrolyte with different water contents and the CdS nanoparticles (CdS NPs) were further deposited onto the TiO2-NTs as a sensitizer via a sequential chemical bath deposition (S-CBD) method. The FE-SEM, TEM, XRD and XPS results demonstrated that the CdS NPs were uniformly deposited onto the surface of TiO2-NTs. It was found that higher water content in electrolyte was in favor of large intertube space and pore size and the uniform deposition of CdS NPs. The photocatalytic degradation of methyl orange was tested with the as-prepared CdS/TiO2-NTs under visible light (λ>400nm). It was found that the photodegradation rate reached as high as 96.7% under visible irradiation for 180min. In addition, a reasonable degradation rate of 75.8% was achieved even after 5 cycles, suggesting a good photocatalytic stability of the as-prepared CdS/TiO2-NTs.

Electrochemical sensor for detection of hydrazine based on Au@Pd core–shell nanoparticles supported on amino-functionalized TiO2 nanotubes

In this paper, we reported a simple strategy for synthesizing well-defined TiO2NTs–Au@Pd hybrid nanostructures with prior TiO2 nanotube functionalization (F-TiO2NTs). TiO2NTs with larger surface area (BET surface area is 184.9m2g−1) were synthesized by hydrothermal method, and the NTs are anatase phase with a range of 2–3μm in length and 30–50nm in diameter after calcined at 400°C for 3h. 3-Aminopropyl-trimethoxysilane (APTMS) as a coupling agent was reacted with the surface hydroxyl groups as anchoring sites for flower-shaped bimetallic Au@Pd nanostructures, self-assembling amine functionality on the surface of TiO2NTs. Note that two faces at the interface between F-TiO2NTs with (004) plane and Au@Pd nanostructures with (111) one of cubic Au and Pd nanoparticles are compatible, benefiting to the charge transfer between two components due to their crystalline coordination. The results showed that as-prepared F-TiO2NTs–Au@Pd hybrid nanostructures modified glassy carbon electrode (GCE) exhibits high electrocatalytic activity toward hydrazine (N2H4) at low potential and a linear response from 0.06 to 700μM with the detection limit for N2H4 was found to be 1.2×10−8M (S/N=3). Based on scan rate effect during the hydrazine oxidation, it indicates that the number of electrons transferred in the rate-limiting step is 1, and a transfer coefficient (α) is estimated as 0.73. The self-assembled F-TiO2NTs–Au@Pd hybrid nanostructures as enhanced materials present excellent electrocatalytic activity, fast response, highly sensitive and have a promising application potential in nonenzymatic sensing.

Reduced graphene oxide and CuInS2 co-decorated TiO2 nanotube arrays for efficient removal of herbicide 2,4-dichlorophenoxyacetic acid from water

Refractory herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) can be efficiently removed by photocatalytic degradation when using reduced graphene oxide (RGO) and CuInS2 nanoparticles (NPs) co-decorated TiO2 nanotube arrays (NTs) (RGO/CuInS2–TiO2 NTs) as a photocatalyst prepared by successive pulse electrodeposition of CuInS2 and RGO film onto the top surface of TiO2 NTs. The new catalyst exhibits significant photocatalytic activity and good removal efficiency of 2,4-D. The photodegradation rate toward 2,4-D over RGO/CuInS2–TiO2 NTs under simulated solar light (or visible light) irradiation is 96.2% (or 87.7%), much higher than 68.0% (or 58.4%) over CuInS2–TiO2 NTs, 50.1% (or 38.1%) over RGO–TiO2 NTs and 36.0% (or 26.3%) over bare TiO2 NTs, respectively, meaning that the photocatalytic performance of TiO2 NTs could be greatly enhanced by the synergetic effect of RGO and CuInS2. This work could provide new insights into the design and fabrication of advanced photocatalysts.

Reduced graphene oxide and PbS nanoparticles co-modified TiO2 nanotube arrays as a recyclable and stable photocatalyst for efficient degradation of pentachlorophenol

TiO2 nanotube arrays (TiO2 NTs) were simultaneously modified by reduced graphene oxide (RGO) and PbS nonoparticles (NPs) through a simple one-step electrodeposition process. RGO film is formed on the top surface of TiO2 NTs and PbS NPs showing size less than 20nm are intercalated within the RGO sheets and also dispersed inside/outside walls the TiO2 NTs. Resulting from the synergetic effect of RGO and PbS, the photocatalytic activity of the ternary RGO/PbS-TiO2 NTs photocatalyst far exceeds those of bare TiO2 NTs, the binary RGO-TiO2 NTs and PbS-TiO2 NTs photocatalysts in the degradation of pentachlorophenol (PCP) under simulated solar light. After 120-min irradiation, almost 100% PCP removal is obtained on the RGO/PbS-TiO2 NTs, compared to 61% on bare TiO2 NTs, 76% on RGO-TiO2 NTs, and 86% on PbS-TiO2 NTs. Because the PbS NPs were covered by the RGO sheets, to a certain extent the photocorrosion of PbS was suppressed, and therefore the RGO/PbS-TiO2 NTs photocatalyst shows a good stability relative to the PbS-TiO2 NTs without RGO. This study will inspire better design of advanced photocatalysts with high visible-light photocatalytic activity, easy recovery, and good stability.

Electrophoresis deposition of Ag nanoparticles on TiO2 nanotube arrays electrode for hydrogen peroxide sensing

In this paper, a simple and green strategy, based on the electrophoresis deposition technology, was reported to prepare Ag nanoparticles (NPs) modified TiO2 nanotube arrays (NTs). The morphologies of AgNPs, TiO2NTs and AgNPs/TiO2NTs were characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The results demonstrate that the surface of TiO2NTs was homogeneously decorated with AgNPs, of which the morphology could be easily controlled by the electrophoretic deposition (EPD) time. In order to investigate the co-effects of AgNPs and TiO2NTs on the catalysis of H2O2, the electrochemical performances of TiO2 NTs, AgNPs/Ti and AgNPs/TiO2NTs electrodes were investigated in this work. It is found that the response of AgNPs/TiO2NTs electrode to H2O2 was remarkably enhanced due to the co-effects of AgNPs and TiO2NTs. Therefore, it could be used to fabricate H2O2 sensor. The effects of conditions were investigated in detail, such as EPD time, the operating potential, etc.. Under the optimal experimental condition, the sensor had a quick response to H2O2 at −0.12V with a high sensitivity (184.24mA·M−1cm−2), wide linear range (0.75μM–11.16mM) and low detection limit (85.6nM). In addition, the sensor also has good stability and excellent selectivity. The developed H2O2 sensor has been successfully applied to the detection of H2O2 in real samples. This work also demonstrated that the AgNPs/TiO2NTs has potential application in fabricating glucose sensor by immobilizing glucose oxidase onto the prepared electrode.

Photocatalytic Activity of Ag/TiO2 Nanotube Arrays Enhanced by Surface Plasmon Resonance and Application in Hydrogen Evolution by Water Splitting

TiO2 nanotube arrays (TiO2 NTs) were fabricated by anodic oxidation and then Ag nanoparticles (Ag NPs) were assembled in TiO2 NTs (Ag/TiO2 NTs) by microwave-assisted chemical reduction. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence spectrum (PL), UV–vis absorption spectrum (UV–vis), and Raman spectrum, respectively. The results showed that Ag NPs were well dispersed on the surface of TiO2 NTs with metallic state. The surface plasmon resonance (SPR) effect of Ag NPs could extend the visible light response and enhance the absorption capacity of TiO2. Furthermore, Ag NPs could also restrain the recombination of photo-generated electron–hole pairs of TiO2 NTs efficiently. The methylene blue photodegradation experiment proved that the SPR phenomenon had an effect on photoreaction enhancement. The results of photocatalytic water splitting indicated that Ag/TiO2 NTs samples had better photocatalytic performance than pure TiO2 NTs. The corresponding hydrogen evolution rate of Ag/TiO2 NTs prepared with 0.002 M AgNO3 solution was 3.3 times as that of pure TiO2 NTs in the test condition. Additionally, the mechanism of catalyst activity enhanced by SPR effect was proposed.

Enhanced Visible‐Light‐Induced Photoelectrocatalytic Degradation of Methyl Orange by CdS Sensitized TiO2 Nanotube Arrays Electrode

AbstractIn this work, CdS sensitized TiO2 nanotube arrays (CdS/TiO2NTs) electrode was synthesized with the CdS deposition on the highly ordered titanium dioxide nanotube arrays (TiO2NTs) by sequential chemical bath deposition method (S‐CBD). The as‐prepared CdS/TiO2NTs was characterized by field‐emission scanning electron microscopy (FE‐SEM) and X‐ray diffraction (XRD). The results indicated that the CdS nanoparticles were effectively deposited on the surface of TiO2NTs. The amperometric I‐t curve on the CdS/TiO2NTs electrode was also presented. It was found that the photocurrent density was enhanced significantly from 0.5 to 1.85 mA/cm2 upon illumination with applied potential of 0.5 V at the central wavelength of 253.7 nm. The photoelectrocatalytic (PEC) activity of the CdS/TiO2NTs electrode was investigated by degradation of methyl orange (MO) in aqueous solution. Compared with TiO2NTs electrode, the degradation efficiencies of CdS/TiO2NTs electrode increased from 78% to 99.2% under UV light in 2 h, and from 14% to 99.2% under visible light in 3 h, which was caused by effective separation of the electrons and holes due to the effect of CdS, hence inhibiting the recombination of electron/hole pairs of TiO2NTs.

Electro-oxidation of hydrazine on gold nanoparticles supported on TiO 2 nanotube matrix as a new high active electrode

Au/titanium dioxide nanotubes (Au/TiO 2-NTs) catalysts are prepared by a simple method using galvanic deposition of gold nanoparticles on TiO 2-NTs as support. TiO 2-NTs are fabricated by anodizing titanium foil in a dimethyl sulfoxide (DMSO) fluoride-containing electrolyte. Scanning electron microscope and energy-dispersive X-ray spectroscopy results indicate that nanotubular TiO 2 layers consist of individual tubes of about 50–80 nm diameters and gold nanoparticles with a size range of 30–40 nm are well-dispersed on the surface of TiO 2-NTs support. The electro-catalytic properties of Au/TiO 2-NTs catalysts toward electro-catalytic oxidation of hydrazine are investigated by cyclic voltammetry. Compared to flat gold electrodes, Au/TiO 2-NTs catalyst shows much higher electrochemical activity. This may be attributed to the uniform dispersion of gold nanoparticles on TiO 2-NTs, smaller particle size and unique properties of TiO 2-NTs support. In addition, the mechanism of hydrazine electrochemical oxidation catalyzed by Au/TiO 2-NTs is investigated.

An innovative electrochemical approach for voltammetric determination of levodopa using gold nanoparticles doped on titanium dioxide nanotubes

Catalytic nanotubes made from titanium dioxide (TiO2-NTs) and covered with gold nanoparticles (Au-NPs) were prepared via galvanic deposition of the Au-NPs on the TiO2-NTs. The morphology and surface characteristics of the resulting electrodes were investigated using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The results indicated that the Au-NPs were homogeneously deposited on the surface of TiO2-NTs which consist of individual tubes of about 40–80 nm in diameter. The AuNPs with a size of 80–100 nm are well-dispersed on the surface of the TiO2-NTs. The electro-catalytic activity of the electrodes towards the electro-oxidation of levodopa was studied by cyclic voltammetry, differential puls voltammetry. The results showed that the electrodes exhibit a considerably higher activity toward the oxidation of levodopa. The oxidation peak current linearly depends on the concentration of levodopa in the 10 to 70 μM concentration range. Levodopa was determined by the method in pharmaceutical preparations, and results were found to be satisfactory.

Novel Pt nanoclusters/titanium dioxide nanotubes composites for hydrazine oxidation

Pt nanoclusters/titanium dioxide nanotubes (nano-Pt/TiO 2-NTs) composites were successfully prepared using TiO 2-NTs as supports. The structure and morphology of the resulting composites were characterized. The results showed Pt nanoclusters with the size ranging from 15 to 20 nm were well dispersed on the surface of TiO 2-NTs. The electrocatalytic properties of nano-Pt/TiO 2-NTs composites for hydrazine oxidation were firstly investigated on the corresponding modified glassy carbon electrode by cyclic voltammetry (CV). The resulting nano-Pt/TiO 2-NTs composites showed excellent electrocatalytic activity. This may be attributed to the small particle size and good dispersion of Pt nanoclusters as well as the unique properties of TiO 2-NTs supports. In addition, the mechanism of hydrazine electrochemical oxidation on Pt/TiO 2-NTs are also investigated. The results imply that TiO 2-NTs are the promising supporting materials for noble catalysts with high activity.

Synthesis and photocatalytic applications of Ag/TiO2-nanotubes

TiO2- and Ag/TiO2-nanotubes (NTs) were synthesized by hydrothermal methods and microwave-assisted preparation, respectively. Scanning electron microscopy, high resolution transmission electron microscopy, Brunauer–Emmett–Teller particle surface area measurement and X-ray diffraction were used to characterize the nanotubes. Rutile TiO2-NTs with Na2Ti5O11 crystallinity had a length range of 200–400nm and diameters of 10–20nm. TiO2- and Ag/TiO2-NTs with a 0.4% deposition of Ag had high surface areas of 270 and 169m2g−1, respectively. The evaluation of photocatalytic activity showed that Ag/TiO2-NTs displayed higher photocatalytic activity than pure TiO2-NTs and a 60.91% degradation of Rhodamine-B with 0.8% deposition of Ag species. Also 60% of Rhodamine-6G was physisorbed and 40% chemisorbed on the surface of TiO2-NTs. In addition, the photocatalytic degradations of organochlorine pesticides taking α-hexachlorobenzene (BHC) and dicofol as typical examples, were compared using Ag/TiO2-NTs, and found that their degradations rates were all higher than those obtained from commercial TiO2.

Synthesis of TiO 2 nanotubes coupled with CdS nanoparticles and production of hydrogen by photocatalytic water decomposition

The CdS/TiO 2NTs composite was prepared by a simple two-step chemical solution routes to directly transfer trititanate nanotubes to TiO 2NTs and simultaneously coupled with CdS nanoparticles. The results of XRD, TEM, Diffuse reflectance UV–Visible absorption spectra revealed that the CdS nanoparticles were homogeneously embedded on the surface of TiO 2NTs and the absorption spectrum of TiO 2NTs was extended to visible region. The activity of hydrogen production by photocatalytic water decomposition for the CdS/TiO 2NTs composite was examined under visible light irradiation ( λ > 400 nm) and the quantity of H 2 evolution was ca. 1708 μL/g for 6 h.

High dispersion and electrocatalytic activity of Pd/titanium dioxide nanotubes catalysts for hydrazine oxidation

Pd/titanium dioxide nanotubes (Pd/TiO 2-NTs) catalysts were prepared by a simple reduction method using TiO 2-NTs as support. The structure and morphology of the resulting Pd/TiO 2-NTs were characterized by transmission electron microscopy and X-ray diffraction. The results showed that Pd nanoparticles with a size range from 6 to 13 nm were well-dispersed on the surface of TiO 2-NTs. The electrocatalytic properties of Pd/TiO 2-NTs catalysts for hydrazine oxidation were also investigated by cyclic voltammetry. Compared to that of pure Pd particles and Pd/TiO 2 particles, Pd/TiO 2-NTs catalyst showed much higher electrochemical activity. This may be attributed to the uniform dispersion of Pd nanoparticles on TiO 2-NTs, smaller particle size and unique properties of TiO 2-NTs support. In addition, the mechanism of hydrazine electrochemical oxidation catalyzed by Pd/TiO 2-NTs are also investigated. The oxidation of hydrazine was an irreversible process, which might be controlled by diffusion process of hydrazine.