Phosphate Nanotubes Research Articles

Tailoring the Growth and Morphology of Lithium Peroxide: Nickel Sulfide/Nickel Phosphate Nanotubes with Optimized Electronic Structure for Lithium-Oxygen Batteries.

Heterogeneous crystalline-amorphous structures, with tunable electronic structures and morphology, hold immense promise as catalysts for lithium-oxygen batteries (LOBs). Herein, a nanotube network constructed by crystalline nickel sulfide/amorphous nickel phosphate (NiS/NiPO) heterostructure is prepared on Ni foam through the sulfurization of the precursor generated hydrothermally. Used as cathodes, the NiS/NiPO nanotubes with optimized electronic structure can induce the deposition of the highly porous and interconnected structure of Li2 O2 with rich Li2 O2 -electrolyte interfaces. Abundant active sites can be created on NiS/NiPO through the charge redistribution for the uniform nucleation and growth of Li2 O2 . Moreover, nanotube networks endow cathodes with efficient transport channels and sufficient space for the accommodation of Li2 O2 . A high discharge capacity of 27 003.6 mAh g-1 and a low charge overpotential of 0.58V at 1000 mAh g-1 can be achieved at 200mA g-1 . This work provides valuable insight into the unique role of the electronic structure and morphology of catalysts in the formation mechanisms of Li2 O2 and the performances of LOBs.

A Laser Technology for Producing Conductive Film and Bulk Composites Based on Calcium Phosphate and Carbon Nanotubes for Bone Tissue Engineering

A Laser Technology for Producing Conductive Film and Bulk Composites Based on Calcium Phosphate and Carbon Nanotubes for Bone Tissue Engineering

Effect of Preparation Conditions on the Morphology and Catalytic Performance of Nickel Phosphate Nanotubes

AbstractNickel phosphate nanotubes are synthesized by a hydrothermal method under different conditions with cetyltrimethyl ammonia bromide (CTAB) as a soft template and urea as an assistant agent. The structure and morphology are characterized by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐Ray powder diffraction (XRD), infrared (IR) spectroscopy, etc. Nickel phosphate nanotubes with different morphologies and structures are prepared at different pH values, crystallization time, molar ratios of Ni to P, CTAB to P, and urea to P. The TEM and SEM results show that the prepared nickel phosphate nanotubes seem like tremella or coral, which consist of nanotubes with a diameter of about 8 nm, length of about 200 nm, a rounded channel, and an open end. The formation process of nanotubes is deduced to be the self‐assembly of nickel phosphate growing along with CTAB. Nickel phosphate nanotubes show special catalytic performance in the isomerization reaction of epoxy propane. The reaction products are mainly propanal, allyl alcohol, and acetone, with a molar ratio of about 5:3:2 and the propylene oxide conversion and selectivity for propanal at 300 ℃ are 74.1% and 49.4%, respectively.

MoOx and WOx conjugated iron phosphate nanotubes catalysts for benzylation of benzene using benzyl alcohol

In this study, we synthesized 5 wt% MoOx and WOx conjugated iron phosphate nanotubes (FeP-NT) catalysts for benzylation of benzene using benzyl alcohol to investigate the role of acid and redox sites. The catalysts were analysed by different techniques along with insitu FT-IR spectroscopy. The 5WOx-FeP-NT catalyst exhibited 100% conversion of benzyl alcohol in 60 min, whereas 5MoOx-FeP-NT catalyst offered only 59% benzyl alcohol conversion in 240 min. The characterization results indicated that high acidity and moderate redox nature of 5WOx-FeP-NT is responsible for better benzyl alcohol adsorption and benzylation activity compared to low acidity and high redox nature of 5MoOx-FeP-NT.

Graphene oxide wrapped Mix-valent cobalt phosphate hollow nanotubes as oxygen evolution catalyst with low overpotential

Development of an efficient, stable and inexpensive catalyst for oxygen evolution reaction (OER) is critical to electrochemical water splitting. In this regard, a precious-metal free electrocatalyst has been synthesized employing a hydrothermal route. The prepared graphene oxide wrapped cobalt phosphate nanotubes deposited on Ni foam electrode shows a low overpotential of 234 mV at a current density of 10 mA/cm2 for OER in 1(M) KOH, lower than a benchmarking electrocatalyst IrO2 at the same current density. The performance figures clearly defy the volcano limitations. The mixed-valency induced delocalization of charge satisfies Sabatier Principle for ideal catalysts and graphene oxide ensures improved charge transfer. Moreover, the designed electrocatalyst performs efficiently even on prolonged use under mass transfer limitation conditions.

New green perspective to dihydropyridines synthesis utilizing modified heteropoly acid catalysts

The classical Hantzsch reaction is a simple and utmost efficient protocol for the synthesis of biologically and pharmacologically important 1,4-dihydropyridine derivatives. The present study deals with the utilization of modified heteropoly acid (HPA) catalysts (5 wt% WOx-FeP and 5 wt% MoOx-FeP) in the synthesis of novel Hantzsch 1,4-dihydropyridines, which contains diphenylsulfone moiety via one-pot synthesis strategy under ultrasound irradiation. The developed protocol is simple and green procedure for the synthesis of 1,4-dihydropyridines and is applicable to synthesize different 1,4-dihydropyridine derivatives. The synthesized HPA catalysts offered a sustainable methodology to produce excellent products yields (88–92%) of 1,4-dihydropyridine derivatives. The catalysts were characterized by XRD, Raman, FT-IR, DRUV-vis, XPS, H2-TPR, N2-physisorption and acidity measurements. The HPA supported iron phosphate nanotubes (FeP) catalysts offered enhanced the catalytic performance through the improved Lewis acid site density, redox properties and surface area, compared to the parent phosphomolybdic and phosphotungstic acids. Moreover, the synthesized catalysts can be easily separated from reaction system and reused for six times efficiently without significant loss of activity.

Strontium Calcium Phosphate Nanotubes as Bioinspired Building Blocks for Bone Regeneration.

Calcium phosphate (CaP)-based ceramics are the most investigated materials for bone repairing and regeneration. However, the clinical performance of commercial ceramics is still far from that of the native tissue, which remains as the gold standard. Thus, reproducing the structural architecture and composition of bone matrix should trigger biomimetic response in synthetic materials. Here, we propose an innovative strategy based on the use of track-etched membranes as physical confinement to produce collagen-free strontium-substituted CaP nanotubes that tend to mimic the building block of bone, i.e., the mineralized collagen fibrils. A combination of high-resolution microscopic and spectroscopic techniques revealed the underlying mechanisms driving the nanotube formation. Under confinement, poorly crystalline apatite platelets assembled into tubes that resembled the mineralized collagen fibrils in terms of diameter and structure of bioapatite. Furthermore, the synergetic effect of Sr2+ and confinement gave rise to the stabilization of amorphous strontium CaP nanotubes. The nanotubes were tested in long-term culture of osteoblasts, supporting their maturation and mineralization without eliciting any cytotoxicity. Sr2+ released from the particles reduced the differentiation and activity of osteoclasts in a Sr2+ concentration-dependent manner. Their bioactivity was evaluated in a serum-like solution, showing that the particles spatially guided the biomimetic remineralization. Further, these effects were achieved at strikingly low concentrations of Sr2+ that is crucial to avoid side effects. Overall, these results open simple and promising pathways to develop a new generation of CaP multifunctional ceramics that are active in tissue regeneration and able to simultaneously induce biomimetic remineralization and control the imbalanced osteoclast activity responsible for bone density loss.

Exploring the possibility of GaPNTs as new materials for hydrogen storage

The possibility of hydrogen storage in gallium phosphate nanotubes (GaPNTs) as a high-capacity hydrogen storage media is studied by employing ab-initio density functional theory (DFT) calculations with a van der Waals (VdW) correction. The binding energy, the distance of the adsorbed hydrogen molecules and the charge transfer were particularly calculated. The obtained results indicate that hydrogenation of the GaPNTs is sensitive to the curvatures and chiralities of the nanotubes. It is found that the binding energy of hydrogen physisorption on GaP nanotubes is higher that on carbon nanotubes. These results are useful in the search for a proper media for hydrogen storage at ambient conditions.

A glassy carbon electrode modified with cerium phosphate nanotubes for the simultaneous determination of hydroquinone, catechol and resorcinol.

A nafion film containing cerium phosphate nanotubes was pasted onto a glassy carbon electrode (GCE) to obtain a sensor for hydroquinone (HQ). The morphologies and components of the coating were characterized by transmission electron microscopy, scanning electron microscopy and energy-dispersive spectroscopy. Cyclic voltammetry and differential pulse voltammetry (DPV) showed the specific surface of the electrode to be significantly increased and the electron transfer rate to be accelerated. The modified GCE was applied to the determination of hydroquinone (HQ) via DPV. The oxidation current increases linearly in the 0.23μM to 16mM HQ concentration range which is as wide as five orders of magnitude. The limit of detection is 0.12μM (based on a signal-to-noise ratio of 3), and the sensitivity is 1.41μA·μM-1cm-2. The method was further applied to the simultaneous determination of HQ, catechol and resorcinol. The potentials for the three species are well separated (20, 134, and 572mV vs SCE). Average recoveries from (spiked) real water samples are between 95.2 and 107.0%, with relative standard deviations of 0.9~2.7% (for n= 3) at three spiking levels. The method was validated by independent assays using HPLC. Graphical abstract ᅟ.

Highly efficient adsorption of uranium(vi) from aqueous solution by a novel adsorbent: titanium phosphate nanotubes

A novel adsorbent (titanium phosphate nanotube) with high performance for U(vi) adsorption was fabricated through a facile solvothermal method.

Effects of Titanium Mesh Surfaces-Coated with Hydroxyapatite/β-Tricalcium Phosphate Nanotubes on Acetabular Bone Defects in Rabbits.

The management of severe acetabular bone defects in revision reconstructive orthopedic surgery is challenging. In this study, cyclic precalcification (CP) treatment was used on both nanotube-surface Ti-mesh and a bone graft substitute for the acetabular defect model, and its effects were assessed in vitro and in vivo. Nanotube-Ti mesh coated with hydroxyapatite/β-tricalcium phosphate (HA/β-TCP) was manufactured by an anodizing and a sintering method, respectively. An 8 mm diameter defect was created on each acetabulum of eight rabbits, then treated by grafting materials and covered by Ti meshes. At four and eight weeks, postoperatively, biopsies were performed for histomorphometric analyses. The newly-formed bone layers under cyclic precalcified anodized Ti (CP-AT) meshes were superior with regard to the mineralized area at both four and eight weeks, as compared with that under untreated Ti meshes. Active bone regeneration at 2–4 weeks was stronger than at 6–8 weeks, particularly with treated biphasic ceramic (p < 0.05). CP improved the bioactivity of Ti meshes and biphasic grafting materials. Moreover, the precalcified nanotubular Ti meshes could enhance early contact bone formation on the mesh and, therefore, may reduce the collapse of Ti meshes into the defect, increasing the sufficiency of acetabular reconstruction. Finally, cyclic precalcification did not affect bone regeneration by biphasic grafting materials in vivo.

Study of the synergistic effect of nickel phosphate nanotubes (NiPO-NT) on intumescent flame retardant polypropylene composites

The nickel phosphate nanotubes (NiPO-NT) were synthesized by hydrothermal method, and its structure was characterized. Then NiPO-NT was added to intumescent flame retardants system in polypropylene (PP) matrix for the first time,and the synergistic effect of NiPO-NT with intumescent flame retardants was studied. The results show that only small content of NiPO-NT can obviously improve the flame retardant and thermal properties of intumescent flame retardant PP composite. With the addition of 0.3 % NiPO-NT, the peak heat release rate of intumescent flame retardant PP composite decreases from 374.7 to 255.5 kW m−2, and the limit oxygen index value increases from 29.9 to 33.9. Meanwhile, the maximum mass loss temperature under N2 atmosphere is increased from 408 to 483 °C.

Heteropolyacid generated on the surface of iron phosphate nanotubes: structure and catalytic activity studies

Structural and catalytic properties of a Mo based heteropolyacid generated after impregnation of MoOx on the surface of porous iron phosphate nanotubes (FeP) were studied.

Facile fabrication of nickel phosphate nanotubes via a urea-assisted hydrothermal route

Nickel phosphate nanotubes (NiPO-NTs) were obtained via a simple urea-assisted hydrothermal route in the absence of organic surfactant as the structure-directing agent. The material possessed an urchin-shaped structure, and the one dimensional nanotubes were directed outward around the spheres. SEM and TEM observations indicated that the NiPO-NTs had an outer diameter of about 7.0 nm, inner diameter of 4.0 nm, and length of around 0.75 μm. It is found that the formation of NiPO-NTs was determined by the pH value and its changing rate, which were controlled by urea hydrolysis. Accordingly, a possible mechanism of nanotube formation was proposed. The synthesized NiPO-NTs showed high catalytic performance in the epoxidation of cyclohexene.

Synthesis of Nickel Phosphate Nanotubes and Their Catalytic Performance for Cyclohexene Epoxidation

Synthesis of Nickel Phosphate Nanotubes and Their Catalytic Performance for Cyclohexene Epoxidation

Cover Picture: Phys. Status Solidi C 6/10

AbstractOn p. 2190 of this issue, Jesús A. Blanco et al. report having succeeded in the synthesis and characterization of γ‐titanium phosphate nanotubes incorporating trioctylamine. The cover picture contains transmission electron microscopy images showing several nanotubes. These nanostructured materials present two or more phases, the interlayer distance being controlled by the alkyl chain length and the amount of amine template as is schematized in the upper part of the picture.The first author, Jesús A. Blanco is an assistant professor at the University of Oviedo, Spain, where he teaches solid state physics and has worked for more than 20 years in materials cience using synchrotron radiation and neutron beam techniques. Current scientific interests are in nanostructured materials and their physical‐chemical properties. (© 2009 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Cerium phosphate nanotubes: synthesis, characterization and biosensing

Cerium phosphate (CeP) nanotubes have been synthesized and confirmed by x-raydiffraction (XRD) and transmission electron microscopy (TEM). The 1D nanomaterial hasa monoclinic crystal structure with a mean width of 15–20 nm and a length up to severalmicrometers. The nanotubes have been employed as electrode substrates for immobilizationand direct electrochemistry of heme proteins/enzymes with myoglobin (Mb) as a model. Theelectrochemical characteristics of the Mb–CeP/GC electrode were studied by voltammetry.After being immobilized on the nanotubes, Mb can keep its natural structure and undergoeffective direct electron transfer reaction with a pair of well-defined redox peaks at−(367 ± 3) mV (pH 7.5). The apparent electron transfer rate constant is(9.1 ± 1.4) s−1. The electrode displays good features in the electrocatalytic reduction ofH2O2, and thus can be used as a biosensor for detecting the substrate with a low detection limit(0.5 ± 0.05 µM), a wide linear range (0.01–2 mM), high sensitivity(14.4 ± 1.2 µA mM−1), as well as good stability and reproducibility. CeP nanotubes can become a simple andeffective biosensing platform for the integration of heme proteins/enzymes and electrodes,which can provide analytical access to a large group of enzymes for a wide range ofbioelectrochemical applications.

Mesoporous Nanotubes of Iron Phosphate: Synthesis, Characterization, and Catalytic Property

Iron phosphate nanotubes with mesoporous walls are solvothermally synthesized using sodium dodecyl sulfate (SDS) as a template. With different template concentrations, various shapes of nanosized iron phosphates can be obtained. When the concentration of SDS is set at the transition regions between the lamellar and the hexagonal mesophases, according to its phase diagram, the coassembly of iron phosphate precursor and SDS forms a flake-type mesoporous iron phosphate. Otherwise, nanoparticles or bulky sheets of iron phosphates are obtained. The followed solvothermal treatments on the mesoporous iron phosphate flakes produce iron phosphate nanotubes with mesoporous walls. The removal of the surfactant by acetate exchange and heat treatment results in the clean mesoporous nanotubes of iron phosphate with diameters of 50-400 nm and lengths of several microns. The nanotubular and mesoporous iron phosphate possesses a specific surface area of 232 m2/g and a bimodal distribution of pore sizes, corresponding to the size of mesopores in the walls and the diameter of the nanotubes, respectively. The novel nanotubular iron phosphate with composite meso-macroporous structure, in favor of the diffusion of reactive molecules, has been tested for direct hydroxylation of benzene with hydrogen peroxide and has shown better catalytic performance compared with the conventional particulate mesoporous iron phosphate.

Cerium Phosphate Nanotubes: Synthesis, Valence State, and Optical Properties

A strong blue emission is observed for hybrid Ce3+/Ce 4+ cerium phosphate nanotubes, whereas Ce3+ phosphate nanowires exhibit a characteristic double-peak UV luminescence (see picture). These cerium phosphate systems were obtained by annealing novel cerium(IV) phosphate nanotubes at different temperatures.

Cerium Phosphate Nanotubes: Synthesis, Valence State, and Optical Properties

Cerium Phosphate Nanotubes: Synthesis, Valence State, and Optical Properties