Iron Hydroxyl Phosphate Research Articles

Bentonite and Biochar Mitigate Pb Toxicity in Pisum sativum by Reducing Plant Oxidative Stress and Pb Translocation.

Lead (Pb)-polluted soils pose a serious threat to human health, particularly by transmitting this heavy metal to the food chain via the crops grown on them. The application of novel amendments in Pb-polluted soils can significantly reduce this problem. In this research, we report the effects of various organic and inorganic amendments i.e., bentonite (BN), biochar (BR), lignin (LN), magnesium potassium phosphate cement (CM) and iron hydroxyl phosphate (FeHP), on the Pb bioavailability in Pb-polluted soil, upon Pb distribution in shoots, roots, grain, the translocation factor (TF) and the bioconcentration factor (BCF) of Pb in pea (Pisum sativum L.) grain. Furthermore, effects of the said amendments on the plant parameters, as well as grain biochemistry and nutritional quality, were also assessed. Lead pollution significantly elevated Pb concentrations in roots, shoots and grain, as well as the grain TF and BCF of Pb, while reducing the nutritional quality and biochemistry of grain, plant height, relative water content (RWC), chlorophyll contents (chl a and chl b) and the dry weight (DW) of shoot, root and grain. The lowest Pb distribution in shoots, roots and grain were found with BN, FeHP and CM, compared to our control. Likewise, the BN, FeHP and CM significantly lowered the TF and BCF values of Pb in the order FeHP > CM > BN. Similarly, the highest increase in plant height, shoot, root and grain DW, RWC, chl a and chl b contents, grain biochemistry and the micronutrient concentrations, were recorded with BR amendment. Biochar also reduced grain polyphenols as well as plant oxidative stress. Given that the BR and BN amendments gave the best results, we propose to explore their potential synergistic effect to reduce Pb toxicity by using them together in future research.

Effect of Li insertion in the crystal structure and magnetism of barbosalite prepared using solvothermal method

The effect of Lithium insertion in the crystal structure and magnetic properties of Barbosalite [Fe3(PO4)2(OH)2], a polymorph of iron hydroxyl phosphate synthesized from variable Fe precursor (Fe(II) and Fe(III)), have been investigated. Effect of distortion in the crystal structure of Barbosalite appeared with minimum lithium hydroxide (LiOH.H2O) concentration of 0.5 M as depicted from the XRD patterns. Further, appearance of fresh peaks from 2 M is well matched with the crystal structure of LiFePO4. Studies with Mössbauer spectroscopy and SQUID Magnetometer intriguingly reveals that Li intercalation in the barbosalite affects only Fe(III) sites whereas the Fe(II) sites remains unaffected till 2 M. However, further increase in the Li concentration leads to structural transformation and results in LiFePO4 phase. Comparative studies of the structural and magnetic properties, magnetic transition are also discussed.

Ultrathin LiFePO4/C cathode for high performance lithium-ion batteries: Synthesis via solvothermal transformation of iron hydroxyl phosphate Fe3(PO4)2(OH)2 nanosheet

A novel two-step solvothermal approach was firstly applied to acquire ultrathin lithium iron (II) phosphate (LiFePO4) nanosheet (with thickness about 28 nm) with exposed (010) surface facets. The iron hydroxyl phosphate Fe3(PO4)2(OH)2 nanosheet fabricated in the first solvothermal step was proved to be effective template for ultrathin LiFePO4 formation after solvothermal lithiation in the second solvothermal step. Importantly, the two-step solvothermal lithiation could produce ultrathin nanosheets while one-step solvothermal based on Fe(II) fabrication could only produce nanoplate-like particles. The as-synthesized nanosheets has shortened Li-ion diffusion path and high robustness in the structure during high C-rate electrochemical tests. Based on comparison with bulk LiFePO4 and nano-plate LiFePO4, the LiFePO4 nanosheet exhibits quite high specific discharge capacity of 169, 165, 159, 142, and 121 mAh g−1, at C-rate of 0.1, 0.2, 0.5, 1, and 5C, respectively, and excellent cycling performance with capacity kept at 121 mAh g−1 with no obvious fading under 500 times cycles. The newly developed method can provide useful references to other olivine type LiMPO4 cathodes and even have potential to find more applications in the synthesis of functional materials.

An iron hydroxyl phosphate microoctahedron catalyst as an efficient peroxidase mimic for sensitive and colorimetric quantification of H2O2 and glucose

An iron hydroxyl phosphate that possesses high peroxidase activity is synthesized via a one-step hydrothermal method and used for colorimetric glucose detection in human serum.

Fabrication of Nanoporous Nickel–Iron Hydroxylphosphate Composite as Bifunctional and Reversible Catalyst for Highly Efficient Intermittent Water Splitting

Global-scale application of water-splitting technology for hydrogen fuel production and storage of intermittent renewable energy sources has called for the development of oxygen- and hydrogen-evolution catalysts that are inexpensive, efficient, robust, and can withstand frequent power interruptions and shutdowns. Here, we report the controlled electrodeposition of porous nickel-iron hydroxylphosphate (NiFe-OH-PO4) nanobelts onto the surface of macroporous nickel foams (NF) as a bifunctional electrocatalyst for efficient whole-cell water electrolysis. The NiFe-OH-PO4/NF electrode shows both high water oxidation and water reduction catalytic activity in alkaline solutions and is able to deliver current densities of 20 and 800 mA cm-2 at overpotentials of merely 249 and 326 mV for oxygen-evolution reaction, current densities of 20 and 300 mA cm-2 at overpotentials of only 135 and 208 mV for hydrogen-evolution reaction. Further, in a two-electrode water electrolytic cell, the bifunctional NiFe-OH-PO4/NF electrodes can obtain the current densities of 20 and 100 mA cm-2 at an overall cell potential of only 1.68 and 1.91 V, respectively. Remarkably, the NiFe-OH-PO4/NF catalyst also represents prolonged stability under both continuous and intermittent electrolysis and can be used for oxygen evolution and hydrogen evolution reversibly without degradation.

Hydrothermal synthesis in presence of carbon black: Particle-size reduction of iron hydroxyl phosphate hydrate for Li-ion battery

Iron hydroxyl phosphate hydrate Fe1.19(PO4)(OH)0.57(H2O)0.43 (FPHH) was obtained by hydrothermal synthesis at 220°C for 6hours. Addition of carbon black to the solution before hydrothermal treatment led to a reduction of the FPHH particle size from ∼10μm in the carbon-free compound to ∼300–500nm in the FPHH-10%C and FPHH-20%C composite with a good dispersion of conducting carbon black. X-ray diffraction, 57Fe Mossbauer spectroscopy and a thermal decomposition study showed that the addition of carbon black did not interfere with the formation of the FPHH phase. Thanks to its favorable microstructural characteristics, the FPHH-10%C and FPHH-20%C material exhibited good performance as positive electrode for Li-ion battery, with high initial discharge capacities of 150, 128 and 112mAhg−1 at 0.25C, 0.5C and 1C rates respectively and 99% capacity retention after 150 cycles at 2C. These results show that addition of solid carbon directly into the solution prior to hydrothermal treatment is a simple and effective way to reduce particle size and also to improve electronic conductivity by dispersing conductive carbon around the active material. This approach is easily transferable to other compounds prepared by hydrothermal synthesis, in order to control particle size while retaining the advantage of crystallization at low temperature.

Glycerin-assisted solvothermal synthesis of Fe3(PO4)2(OH)2 microspheres

Iron hydroxyl phosphate (Fe3(PO4)2(OH)2) microspheres with diameters of several micrometers have been successfully prepared using Fe(NO3)3·9H2O and NaH2PO4·2H2O in a mixed solvent of deionized water and glycerin by a facile one-step solvothermal method. The crystal phase of the product changes from poorly crystallized FePO4·2H2O nanoparticles into well-crystallized Fe3(PO4)2(OH)2 microspheres as the amount of glycerin increases. The as-prepared Fe3(PO4)2(OH)2 microspheres can transform into FePO4 through thermal treatment at 800°C in air. The cytotoxicity tests show that the as-prepared Fe3(PO4)2(OH)2 microspheres have good biocompatibility. We expect that the as-prepared Fe3(PO4)2(OH)2 microspheres are promising for the applications in various fields.

Simultaneous immobilization of lead, cadmium, and arsenic in combined contaminated soil with iron hydroxyl phosphate

Purpose Combined contamination of lead (Pb), cadmium (Cd), and arsenic (As) in soils especially wastewater-irrigated soil causes environmental concern. The aim of this study is to develop a soil amendment for simultaneous immobilization of Pb, Cd, and As in combinative contaminated soil.

Hierarchical growth and shape evolution of iron hydroxyl phosphate dendrites obtained without surfactants for highly efficient adsorption of DNA

ABSTRACTIn the current study, novel hierarchical Fe5(PO4)4(OH)3·2H2O dendrites were synthesized via a simple hydrothermal system in the absence of surfactants employing FeCl3·7H2O and NaH2PO4 as the starting materials. Scanning electron microscopy analysis showed that the product is comprised of particles having long central trunks with secondary branches, preferentially grown in a parallel direction with a definite angle to the trunks. The effects of the experimental parameters on the morphology of the resultant materials were investigated. Ostwald ripening and the self-assembly process were proposed as a possible formation mechanism. Adsorption tests of macromolecular salmon sperm DNA demonstrated high adsorption efficiency, revealing the promising applicability of the synthesized dendrites to enhanced DNA separation or drug/gene delivery.

Doped Framework Iron Hydroxyl Phosphate as Photocatalyst for Hydrogen Production from Water/Methanol Mixtures

AbstractIn the search for novel photocatalysts for hydrogen production and with the α‐Fe2O3 photoelectrocatalyst as a recent precedent, we report herein the preparation, semiconductor properties and photocatalytic activity of metal‐doped (0.1–5 wt.‐% loading) iron hydroxyl phosphate (FeP). X‐ray diffraction analyses of FeP samples subjected to extended photocatalytic irradiation showed the stability of this framework phosphate under photocatalytic conditions. Doping increased the photocatalytic efficiency of FeP for all dopants, with the optimal doping level between 0.1 and 1 %. Under the optimized conditions (Cr at 1 % doping), the photocatalytic activity of FeP reached a hydrogen production rate of 35.82 μmol gFe–1 in the absence of platinum as co‐catalyst. The conduction flat band potential was estimated by photocurrent measurements or impedance spectroscopy to be 0.1 eV versus NHE and the charge carrier density 2.6 × 1020 carriers cm–3. Transient absorption spectroscopy revealed a transient species decaying on the microsecond timescale characterized by a broad band spanning 300–750 nm. This transient was attributed to the charge‐separated state. These results are promising for the development of novel photocatalytic materials based on framework metal phosphate.

Single-Crystalline Hyperbranched Nanostructure of Iron Hydroxyl Phosphate Fe5(PO4)4(OH)3·2H2O for Highly Selective Capture of Phosphopeptides

Single-crystalline hyperbranched nanostructures of iron hydroxyl phosphate Fe5(PO4)4(OH)3·2H2O (giniite) with orthorhombic phase were synthesized through a simple route. They have a well-defined dendrite fractal structure with a pronounced trunk and highly ordered branches. The toxicity test shows that the hyperbranched nanostructures have good biocompatibility and low toxicity level, which makes them have application potentials in life science. The study herein demonstrated that the obtained hyperbranched giniite nanostructures show highly selective capture of phosphopeptides and could be used as a kind of promising nanomaterial for the specific capture of phosphopeptides from complex tryptic digests with the detection of MALDI-TOF mass spectrometry.

Influence of Iron Hydroxyl Phosphate Particles on the Thermal Stability and Combustible Properties of Polymethyl methacrylate

The iron hydroxyl phosphate Fe3.6Fe1.02(OH)2.17(PO4)3O0.84(FePOH) nanoparticles were synthesized by hydrothermal method at a relative low temperature. The iron hydroxyl phosphate nanoparticles were then incorporated into poly (methyl methacrylate) (PMMA) by in situ radical polymerization. Thermogravimetric analysis (TGA) data showed that the presence of FePOH remarkably improved thermal stability and promoted the formation of char residues of PMMA matrix. For the PMMA in combination with 6 % FePOH, the heat release capacity which is an indicator of a material fire hazard was reduced by 48 %. The residue characterization and thermogravimetric analysis/fourier transform infrared spectrometry (TGA-FTIR) revealed the carbonization behavior of iron hydroxyl phosphate in PMMA matrix and probably the appearance of Fe(CO)5 during the thermal decomposition of PMMA/2 %FePOH composite, which may is the reason for the improvement in the thermal and combustion properties.

Synthesis, morphological analysis and electrochemical performance of iron hydroxyl phosphate as a cathode material for lithium ion batteries

Iron hydroxyl phosphate, with the formula Fe1.5(PO4)(OH), used as a cathode material in lithium ion batteries, is synthesised by a sample hydrothermal method. Scanning electron microscopy (SEM), X-ray diffraction and galvanostatical charge/discharge tests are employed to characterise the morphology, structure and electrochemical performance of the iron hydroxyl phosphate, respectively. FE-SEM shows that the morphologies are closely related to the hydrothermal temperatures at which they are synthesised. The morphologies, such as spherical, cubic, multi-armed and cross-like structures, could be easily regulated by adjusting the hydrothermal temperature. It is found that different morphologies of iron hydroxyl phosphate gave rise to different electrochemical performances. Compared to the others, iron hydroxyl phosphate spherical composites exhibit not only a high reversible capacity but also good cycling stability, with a reversible initial discharge specific capacity of around 176 mAh g−1 and a remaining 95% of the initial discharge specific capacity after 60 cycles at 0.1C. The improved electrochemical performance is attributed to the spherical morphology and smaller particle size, which increase the reaction interfaces and shorten the diffusion distance of the lithium ions.

Synthesis of single-crystal dendritic iron hydroxyl phosphate as a Fenton catalyst

In this work, the single-crystal dendritic iron hydroxyl phosphate is synthesized via a facile and well-controlled hydrothermal process without any additional surfactant or template. The morphology of the product at various scales is characterized by scanning electron microscopy and transmission electron microscopy. The phase and crystal structure is determined and carefully confirmed by using X-ray powder diffraction, high resolution transmission electron microscopy and selected area electron diffraction combined with thermal analysis comprehensively. A reasonable self-template route, as well as the precipitation–dissolution–recrystallization process is revealed according to the time dependence of morphology, crystal structure, zeta potential and precipitate amount. Finally, the single-crystal dendrite is tested as a Fenton catalyst for the degradation of phenol, a typical advanced oxidation process (AOP). Attributed to the perfect crystal structure and the hierarchical architecture, this novel catalyst presents numerous advantages including remarkable catalytic activity over a wide pH range (e.g., pH = 3–8), outstanding cycle performance (no observation of activity loss in five runs), and extremely low leaching iron concentration (below 0.5 mg L−1).

Iron hydroxyl phosphate microspheres: Microwave-solvothermal ionic liquid synthesis, morphology control, and photoluminescent properties

A variety of iron hydroxyl phosphate (NH 4Fe 2(PO 4) 2OH·2H 2O) nanostructures such as solid microspheres, microspheres with the core in the hollow shell, and double-shelled hollow microspheres were synthesized by a simple one-step microwave-solvothermal ionic liquid method. The effects of the experimental parameters on the morphology and crystal phase of the resultant materials were investigated. Structural dependent photoluminescence was observed from the double-shelled hollow microspheres and the underlying mechanisms were discussed.

Stability, electrochemical behaviors and electronic structures of iron hydroxyl-phosphate

Iron hydroxyl-phosphate with a uniform spherical particle size of around 1 μm, a compound of the type Fe 2− y □ y (PO 4)(OH) 3−3 y (H 2O) 3 y−2 (where □ represents a vacancy), has been synthesized by hydrothermal methods. The particles are composed of spheres of diameter <100 nm. The compound exhibits good electrochemical performance, with reversible capacities of around 150 mAh g −1 and 120 mAh g −1 at current densities of 170 mA g −1 and 680 mA g −1, respectively. The stability of crystal structure of this material was studied by TGA and XRD which show that the material remains stable at least up to the temperature 200 °C. Investigation of the electronic structure of the iron hydroxyl-phosphate by GGA + U calculation has indicated that it has a better electronic conductivity than LiFePO 4.

Theoretical Study of a New Cathode Material of Li-Battery: Iron Hydroxyl-phosphate

The charge/discharge process and electronic structure of iron hydroxyl-phosphate (Fe2−y◻y(PO4)(OH)3−3y(H2O)3y-2) are investigated by density functional theory (DFT) calculation under the GGA+U scheme. The calculation results show that the intermediate phase LixFe1.25(PO4)(OH)0.75(H2O)0.25 does not separate into the two end phases, Fe1.25(PO4)(OH)0.75(H2O)0.25 and Li1.25Fe1.25(PO4)(OH)0.75(H2O)0.25, during lithium insertion/extraction. The most striking feature of voltage−composition curve is the presence of a sloping voltage curve on charge and discharge, which is a characteristic of a single-phase charge/discharge behavior. It is attributed to the high concentration vacancy defects and the different topological and chemical local structures around the defects. No obvious band gap is observed, and unoccupied states locate around the Fermi level for the LixFe1.25(PO4)(OH)0.75(H2O)0.25 (0 < x<1). The energy band structure implies that this material is a two-dimensional electron conductor.

New Iron (III) Hydroxyl-Phosphate with Rod-packing Structure as Intercalation Materials

ABSTRACTA new iron hydroxyl-phosphate, H2Fe14/3(PO4)4(OH)4 has been synthesized under hydrothermal conditions. In this compound, perpendicular chains formed by the face-sharing FeO6 form rod-packing structure. Only about 60% of the chain sites are occupied by iron atoms; other metals, such as manganese, nickel, zinc, can be incorporated into the chain either by filling in the vacancies and/or replacing some of the iron atoms. Reversible insertion and extraction of lithium into this compound shows it to be an excellent cathode material. At current density of 0.1 mA/cm2, 90 % of the theoretical capacity (176 mAh/g) can be obtained. The utilization was reduced to about 70 % on a ten-fold increase of current density. The electrochemical behavior is attributed to the 3-dimensional rod packing structure, where lithium can move freely even at high current densities inside the 3-dimensional framework without altering the host structure. Two of the protons in the lattice may be exchanged by lithium giving Li2Fe14/3(PO4)4(OH)4. These lithium atoms are not removable in electrochemical cycling and similar electrochemical property was found for these two compounds, suggesting an ion-exchange process for the lithiation.