Search

For most of WO 3 , a visible-light-driven photocatalyst, its barrier in photocatalytic degradation is the low conduction band (CB) potential that can not reduce O 2 to O 2 − and HO 2 radicals and thus results in fast recombination of electron/hole. With this in mind, a new active FeWO 4 /Fe 2 O 3 di-modified WO 3 was designed and prepared via by a straightforward but effective strategy by introducing of FeWO 4 and Fe 2 O 3 clusters (or nanoparticles) on WO 3 . The performance of di-modified WO 3 showed super high photocatalytic activity in degrading quasi-phenothiazine dyes of Methylene blue (MB), Toluidine blue (TB), Azure I (AI) and Acridine orange (AO) under visible light irradiation, and the corresponding k values are 5.3, 4.4, 3.8 and 5.8 times larger than that of pure WO 3 , respectively. This improvement was mainly due to the fact that photoexcited electrons can migrate to the matching CB of firmly and highly dispersed FeWO 4 and Fe 2 O 3 , then be consumed rapidly by a valence decrease from Fe 3+ to Fe 2+ and Fenton reaction between Fe 2+ and H 2 O 2 . And the strong adsorption of Fe species toward N and S (or N) elements in quasi-phenothiazine dyes, also positively promoted the efficiency of degradation.

Hexagonal boron nitride nanosheets (BNNSs), which show outstanding thermal conductivity and chemical stability, have drawn more and more attention in recent years. However, the limited yield, dispersivity and the polydispersed size of the exfoliated ones hinder their further application. Here, we present a method of effective and scalable synthesis of quasi-monodispersed BN colloidal nanocrystals by “solid-state synthesis” combined with “solvent cutting” technique. The key of the technique is the imperfect nitridation of the BO species, which yield the boron oxides and amorphous BN that coexist with the well crystallized BN domains. As the impurities that separate the well crystallized BN domains are removed, the BN skeleton with better crystallinity is remained. The BN colloidal nanocrystals are obtained when the solvents cut the weak grain boundary in BN skeleton. The lateral size of as-prepared BN colloidal nanocrystals could be well controlled for 3 nm, 10 nm and 20 nm. The zeta potentials of colloid are below −30 mV in a pH range of 5–12. That means the BN colloid can keep high colloidal stability over a wide pH range. As an exemplary application of colloidal BN nanocrystals, the BN film is coated on the copper foil by a simple dip-coating method. The coated copper foil shows remarkable anti-electrochemical corrosion property. This study not only paves a way for the synthesis of colloidal BN nanocrystals, but also gives an alternative choice for a facile and low cost protective BN coating.

Compared with mushroomed progress in metal-free C-rich BCN catalysts, little is known about the BN-rich BCN or even BN ones. Its related study has drawn great interest recently but still in its infancy stage. In this study, three kinds of BCN nanosheets (NSs) with tuned surface carbon contents (5.5–14.3%), specific surface area (SSA, 82–290 m2/g) and morphologies (ultrathin nanosheets, triangular plates) were fabricated through a solid state reaction by simply adjusting the reaction temperature, and those effects on the ethylbenzene dehydrogenation performances were studied in CO2 atmosphere. The morphology evolution of BCN NSs from ultrathin nanosheets to the triangular plates was observed and control experiments were carried out. The BCN nanosheets show relatively strong interaction with CO2 and distinct CO2 absorption properties. The CO2 temperature programmed desorption also indicates that the desorption peaks of CO2 are above 400 °C, enabling them potential CO2 utilization catalysts. A weak association was found between the surface C contents and the catalytic performance as it normalized with SSA, and the B-O species could be taken as an active site in CO2 atmosphere. Though much progress still needed, it is convincing that the BCN catalyst could be a promising metal-free catalyst in dehydrogenation beyond carbocatalyst.

A one-pot facile, impurity-free hydrothermal method to synthesize ultrathin α-FeOOH nanorods/graphene oxide (GO) composites is reported. It is directly synthesized from GO and iron acetate in water solution without inorganic or organic additives. XRD, Raman, FT-IR, XPS and TEM are used to characterize the samples. The nanorods in composites are single crystallite with an average diameter of 6 nm and an average length of 75 nm, which are significantly smaller than GO-free α-FeOOH nanorods. This can be attributed to the confinement effect and special electronic influence of GO. The influences of experimental conditions including reaction time and reactant concentration on the sizes of nanorods have been investigated. It reveals that the initial Fe2+ concentration and reaction time play an important role in the synthetic process. Furthermore, a possible nucleation-growth mechanism is proposed. As electrode materials for supercapacitors, the α-FeOOH nanorods/GO composite with 20% iron loading has the largest specific capacitance (127 F g−1 at 10 A g−1), excellent rate capability (100 F g−1 at 20 A g−1) and good cyclic performance (85% capacitance retention after 2000 cycles), which is much better than GO-free α-FeOOH nanorods. This unique structure results in rapid electrolyte ions diffusion, fast electron transport and high charging-discharging rate. In virtue of the superior electrochemical performance, the α-FeOOH nanorods/GO composite material has a promising application in high-performance supercapacitors.

The correlation between the catalytic activities and electrochemical features of MoSx material is important to study the work process of structure on catalytic performance. In this work, adopting the centimeter-scale ultra-thin MoSx film as a research model, we try to establish a persuasive electrochemical features–catalysis correlation in two different ultra-thin MoSx structures, of which one is O contaminated and another is O free. The results indicate that whatever the structure of MoSx is, high turnover frequency (TOF) and large cathodic current density (J) require low charge-transfer resistance (Rct); low over-potential (η) requires low charge-transfer resistance (Rct) and rich active sites; low Tafel slope requires the high activity of the active sites; and high exchange current densities (Jo) requires a match between the activity of the active sites and Rct. These results provide useful information for the further improvement of MoSx material. From the catalytic activities we can infer which parameters of the electrochemical features need to be improved, and then selectively adjust its physical structure.

Two kinds of 3D hierarchical α-Fe 2 O 3 nanoparticles, flower-like structure with the (0 0 1) plane predominantly exposed on petals and urchin-like structure with nanorods grown along [0 0 1] direction, have been synthesized under the influence of glycerol by a facile hydrothermal method. It is proposed that the Fe(III)–glycerol micro-reaction units that selectively adsorb to (0 0 1) or other planes result in different morphologies. The adsorption of Cr(VI) from aqueous solution onto these α-Fe 2 O 3 nanoparticles showed that the removal efficiency up to 98.5% and 88.8% in 25 mg/L Cr(VI) solution, and the adsorption capacity reaches to 34.4 mg/g and 26.0 mg/g without pH adjustment. The adsorption kinetic is well described by the pseudo-second-order model and the Cr(VI) adsorption on the adsorbent agrees well with the Langmuir model. Lower surface areas and more excellent adsorption property associates with the chemisorption of Cr(VI) onto α-Fe 2 O 3 (0 0 1), which is achieved by coordination between Cr(VI) and doubly or triply coordinated hydroxyl groups on α-Fe 2 O 3 surface.

Herein, tungsten oxide hexagonal prisms with a biphase of h-WO3 and o-WO3·0.33H2O were prepared by a facile hydrothermal method using Fe3+ cations. The combination of instrumental characterization and software simulation proved that two phases coexisted in one nanoparticle with same morphology. The ratio of two phases could be changed by adjusting the concentration of Fe3+ cations. On the basis of controlled experiments, a mechanism was proposed to illustrate the formation of this biphase WO3 structure, and it was also proved that the self-growth of Fe species was unfavorable for the coexistence of two phases.

The replacement of superheated steam with CO 2 for ethylbenzene (EB) dehydrogenation to produce styrene (ST) is of great importance from both scientific and practical perspectives, while it is still a big challenge to design and synthesize catalysts for dehydrogenation in the presence of CO 2 . Research into shape-controlled nanocrystals has proved that well-defined facets are of great importance for understanding the catalytic phenomena due to their definite surface structure. In the present work, α-Fe 2 O 3 nanocrystals enclosed by various crystal facets provide us the clue to understand the role of CO 2 in dehydrogenation. O(III) (the triply coordinated surface oxygen atom) is found to play an important role in activating CO 2 under reaction conditions, which is supported by both experimental and theoretical results. These results have deepened knowledge about the role of CO 2 in dehydrogenation over pure α-Fe 2 O 3 catalysts, which is significant in designing relative catalysts rationally.

In this study, porous activated carbon balls supported by nanoscale zero-valent iron composites (Fe@PACB-700) were used for the first time for the removal of trace Cr(VI) from aqueous solutions. The Fe@PACB-700 composites were prepared by a facile carbothermal reduction method and then characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that nZVI particles have been successfully loaded onto PACBs. Fe@PACB-700 shows an excellent Cr(VI) removal efficiency of 91.2%. The maximum adsorption capacity of Fe@PACB-700 for Cr(VI) is 22.24 mg/g, which is 4.36 times that of PACB. The residual Cr(VI) concentration is below 20 ppb with the use of 0.15 g of Fe@PACB-700, which is much lower than the allowable concentration for Cr(VI) in drinking water (0.05 mg/L). The adsorption of Cr(VI) can be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. Fe@PACB-700 still has a high removal efficiency of 80% after five cycles. Thus, Fe@PACB-700 has a great potential for Cr(VI) removal from aqueous solution. Graphical abstract.

Herein, the functions of a N dopant in crystalline MoS

A vacuum sample chamber for SAXS measurement of solutions was developed to improve the signal-to-noise ratio of the instrument at Beijing Synchrotron Radiation Facility (BSRF). We developed a vacuum sample chamber which could be connected to the upstream and the downstream vacuum tubes by bellows. Horizontal and vertical linear slides were mounted in the vacuum chamber to adjust the sample position by 35 mm in the horizontal and vertical directions to align the sample in the light path. The liquid sample holder of the chamber was sealed with polyimide film by squeezing instead of gluing to avoid the potential influence of sealant on the solution. The chamber had been used for SAXS measurements of water and bovine serum albumin solution at BSRF. The results showed that the background scattering intensity in air was much higher than that in vacuum, especially in the small-angle area near the beamstop. When the q value is 0.142 nm−1, 1.01 nm−1 and 1.25 nm−1, the background scattering intensity in air is 45, 6.8 and 4.6 times of that in vacuum, respectively. And the background-subtracted scattering curves of bovine serum albumin solution (10 mg/ml) in air and vacuum differ in intensity by a factor of about 2. When the q value is 2 nm−1, the signal-to-noise ratios of scattering intensity of BSA in air and vacuum are 0.79 and 8.51, respectively. We designed a simple vacuum sample chamber to be used on the SAXS instrument at 1W2A station of BSRF. The scattering of the background and protein solution in air and vacuum was tested and compared, and the signal-to-noise ratio was clearly improved.

Carboxyl Fe

Nitrogen-doped graphene is a promising candidate for the replacement of noble metal-based electrocatalysts for oxygen reduction reactions (ORRs). The addition of pores and holes into nitrogen-doped graphene enhances the ORR activity by introducing abundant exposed edges, accelerating mass transfer, and impeding aggregation of the graphene sheets. Herein, we present a straightforward but effective strategy for generating porous holey nitrogen-doped graphene (PHNG) via the pyrolysis of urea and magnesium acetate tetrahydrate. Due to the combined effects of the in situ generated gases and MgO nanoparticles, the synthesized PHNGs featured not only numerous out-of-plane pores among the crumpled graphene sheets, but also interpenetrated nanoscale (5–15 nm) holes in the assembled graphene. Moreover, the nitrogen doping configurations of PHNG were optimized by post-thermal treatments at different temperatures. It was found that the overall content of pyridinic and quaternary nitrogen positively correlates with the ORR activity; in particular, pyridinic nitrogen generates the most desirable characteristics for the ORR. This work reveals new routes for the synthesis of PHNG-based materials and elucidates the contributions of various nitrogen species to ORRs.

As electromagnetic pollution is becoming more and more serious, novel composite microwave absorbents are gaining much attention. In this work, low-cost glucose was used as a carbon source to prepare hydrochar, and Fe–Fe3C/C microspheres for microwave absorption were successfully synthesized through the hydrothermal synthesis of Fe3O4/hydrochar and subsequent high-temperature carbonization at different temperatures. The results showed that the Fe–Fe3C nanoparticles were uniformly loaded on the carbon microspheres. Resulting from the synergistic effect of Fe–Fe3C nanoparticles and partially graphitized carbon, a wide region of microwave absorption was achieved due to dual dielectric and magnetic losses. An effective bandwidth of reflection loss less than −10 dB could reach up to 4 GHz with 1.5 mm thickness. Owing to the characteristics of the cost-effective synthetic route, low density and good microwave absorption with thin thickness, the Fe–Fe3C/C microspheres could be used as a lightweight and highly efficient microwave absorbent.

A series of Co3O4 nanocrystals with systematic shape evolution from octahedra to corner-truncated octahedra, corner-truncated cubes, globate polyhedra and micro-spheres were successfully synthesized under the influence of C2O42− and PVP. It was proved that crystal facet growth limitation caused by the adsorption of C2O42− and PVP on the surface of Co3O4 particles played a crucial role in this shape evolution process. Besides obtaining a series of intermediate Co3O4 nanocrystals exposing different facets, this strategy could also show the relationship between these structures. The present work extends the PVP-assisted method to realize the shape evolution process of metal oxide nanomaterials.

Co3O4 microparticles, with many smooth quadrihedrons on the surface, were hydrothermally synthesized under the influence of EDTA2− anions. Due to the excellent chelating and capping ability of EDTA2−, the as-obtained Co3O4 microparticles were mainly enclosed by (111) and (113) facets or their equivalent facets. On the basis of condition-dependent experiments, a dehydration condensation reaction assisted by the limitation effects of EDTA2− adsorbed on the surfaces of Co3O4 was proposed to explain the growth process of the cubic crystalline Co3O4 microparticles. The as-obtained Co3O4 microparticles could catalyze the thermal decomposition of ammonium perchlorate (AP) effectively due to the exposure of the high energy facets.

The boron nitride nanosheets (BNNSs) have attracted great interest in the field of energy storage and heterogeneous catalysis. In this paper, BNNSs supported iron (Fe/BNNSs) catalysts were prepared by one-pot solid state reaction and used in Fischer–Tropsch synthesis (FTS) for the first time. The microscopic structure, morphology and metal–support interaction of the Fe/BNNSs catalysts were investigated by TEM, FT-IR, 1H MAS NMR and H2-TPR. The average thickness of the N-rich BNNSs support was 4–8 nm, and the mean size of the iron nanoparticles was 25–40 nm. The CO conversion, CH4 and C5+ selectivity of typical Fe/BNNSs catalyst with 33 wt% Fe-loading were 47%, 13.7% and 48% at 270 °C, respectively. No obvious deactivation was observed even after 270 h running. The conversion, selectivity and the iron time yield (FTY) of Fe/BNNSs catalysts were highly related to the loading, dispersion of iron nanoparticles. The lower loading and better dispersion of the iron nanoparticles in Fe/BNNSs catalyst resulted in the better FTY and C5+ selectivity. The N-rich defects of BNNSs and porous structure of BNNSs anchored active phases to prevent them from growing larger. Therefore, the BNNSs support plays an important role in retarding the catalyst from deactivation.

Despite the significant progress in making hollow structures, it is still a challenge to synthesize some specialized hollow structures. In the present work, we obtained a new hollow hematite structure, tube-in-dodecahedron, by using the stepwise influences of fluoride and phosphate anions. Based on condition-dependent experiments, we proposed a “nucleation–aggregation–recrystallition and etching” mechanism, which also directed us to synthesize a series of hematite hollow structures, including hollow dodecahedron and hollow ellipsoid. The concentration of phosphate was found to play a decisive role in the control of these hollow structures. 0.08 mM is the critical point for keeping the top facets of dodecahedral hematite particles while 0.2 mM is the upper limit for keeping the lateral facets. The magnetic properties of these synthesized hollow hematite structures were found to be closely associated with the structures. The synthesized tube-in-dodecahedral hematite particles exhibited excellent photocatalytic reactivity toward organic dyes.

Carbonization can enhance the utilization of coal. Pore structure is the main feature of the physical structure of coal and its carbonization products as char and coke. In this work, we performed an in-situ small angle X-ray scattering (SAXS) study on high temperature carbonization (1200 °C) of a kind of lignite and a kind of sub-bituminous coal. The variation of pore structure including pore size distribution, porosity and specific surface area of coal illustrates the different stages of the carbonization process.

Ni modified MoO3 (Ni-MoO3) had been synthesized by a facile one-step hydrothermal technique and was used for oxidative desulfurization (ODS) of dibenzothiophene (DBT) in the decalin/acetonitrile biphasic system with H2O2 as oxidant, the effect of different operating conditions was investigated. Under the optimal reaction condition, Ni-MoO3 catalyst showed excellent ODS performance toward DBT, the highest sulfur removal efficiency can be up to 99.8% and sulfur content was wiped out from 5000 to 10 ppm, which is more effective than the recent reported MoO3-based catalysts. The reaction kinetics obeyed the pseudo-first-order equation with an apparent rate constant of 0.076 min−1, which is twice that of pure MoO3 (0.035 min−1). The ODS mechanism of DBT with Ni-MoO3 was explored by combining radical scavenger, FT-IR experiments and theoretical analysis, proving that surface oxygen vacancies and Lewis acid sites play important roles in the high-efficiency ODS reaction with Ni-MoO3 catalyst.

In this work, we demonstrated a facile template-free method for the preparation of hollow CuO microspheres via a conventional hydrothermal reaction. The hollow architecture formed directly during the hydrothermal treatment of copper nitrate and glucose, without the use of template, precipitant and calcination process. The effects of reaction time, reaction temperature and glucose concentration were investigated in detail. On the basis of experimental results, the formation of hollow CuO microspheres probably proceeded via self-assemble process and the subsequent Ostwald's ripening. This synthetic strategy strongly depended on the characteristics of copper nitrate, which made it could not extend to other copper salts and/or nitrates. Even though, glucose still showed efficient morphology controlling ability with respect to nanosized transitional metal oxides, which could be used for the controllable synthesis of nanomaterials.

A series of single-crystalline Co3O4 nanoparticles with shapes of an octahedron, a corner-truncated octahedron, a cube, a corner-truncated cube and a cuboctahedron were obtained by restructuring polycrystalline Co3O4 microspheres under the assistance of acetic acid. It was proved that the ionization equilibrium of acetic acid in the reaction system played a crucial role in the restructuring process. Besides obtaining a series of intermediate Co3O4 nanocrystals, this strategy could also show the internal relationship between these structures. This acid assisted restructuring method provides us a new route to modify the microstructure of metal oxide particles.

Co 3 O 4 nanowires, with the length of tens of micrometers and the width of several hundred nanometers, were produced by a hydrothermal treatment and a post-anneal process. X-ray diffraction (XRD) result showed that the Co 3 O 4 nanowires belong to cubic crystal system. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that the Co 3 O 4 nanowires, composed by single crystalline nanoparticles, were of polycrystalline nature. On the basis of time-dependent experiments, methanamide-assisted hydrolysis and subsequent dissolution–recrystallization process were used to explain the precursors' formation process of the polycrystalline Co 3 O 4 nanowires. The TGA experiments showed that the as-obtained Co 3 O 4 nanowires can catalyze the thermal decomposition of ammonium perchlorate (AP) effectively.

With the continuing growth in demand for the reduction of electromagnetic radiation, lightweight and highly efficient microwave absorbents are greatly needed. In this study, Fe3O4@C core–shell nanotubes, with Fe3O4 nanotubes as cores and carbon as shells, of about 10 nm thickness have been successfully synthesized. Coating Fe3O4 nanotubes with carbon shells effectively increased dielectric loss and improved impedance matching of the composites, resulting in enhanced microwave absorption performance. The effective absorption bandwidth, with reflection loss (RL) less than −10 dB, was up to 6 GHz when the thickness of the test sample was as little as 1.7 mm, as determined using a vector network analyzer. Possessing a very low density of 1.4 g cm−3 and good microwave absorption performance, the as-fabricated Fe3O4@C core–shell nanotubes can meet the multiple property requirements of microwave absorbents.

NiO nanospindles were successfully synthesized via a hydrothermal and post-treatment method. The as-synthesized nanospindles were about several hundred nanometers in width and about one micrometer in length. X-ray diffraction (XRD) analysis revealed that the spindle-like structure was cubic NiO phase crystalline. Scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analysis indicated that these NiO nanospindles were of single crystal nature. On the basis of time-dependent experiments, a possible agglomeration–dissolution–recrystallization growth process was proposed to explain the formation process of the spindle-like precursors. The cyclic voltammetry (CV) measurement showed that the as-prepared spindle-like NiO exhibited a pseudo-capacitance behavior.

A small sample stretcher for in-situ measurement of small angle X-ray scattering (SAXS) was developed, which consists of stretch, transmission, detection and control systems. The basic parameters of the stretcher are: tension ≥ 400 N, 3 mm/min ≤ stretching speed ≤ 50 mm/min, sample length ≤ 30 mm, stroke ≥ 80 mm, and resolution = 50 μm. The stretcher is compact and has low stretching speed and convenient remote control. It is suitable for in-situ SAXS measurements on stretching of carbon fibers, polyethylene and other samples. Such measurement were carried out with high density polyethylene (HDPE) on the SAXS instrument at the 1W2A station of Beijing Synchrotron Radiation Facility (BSRF). The result verified the effectiveness of the stretcher.

Uniform rhombohedral α-Fe2O3 nanoparticles, ∼60 nm in size, were synthesized via a triphenylphosphine-assisted hydrothermal method. Scanning electron micrograph (SEM) and transmission electron micrograph (TEM) analyses showed that the as-synthesized rhombohedral nanoparticles were enclosed by six (1 0 4) planes. The concentration of triphenylphosphine played an important role in morphological evolution of the α-Fe2O3 nanoparticles. The as-prepared rhombohedral nanoparticles possessed remanent magnetization Mr of 2.6 × 10−3 emu/g and coercivity HC of 2.05 Oe, both lower than those of other α-Fe2O3 particles with similar size, indicating their potential applications as superparamagnetic precursor materials. Furthermore, these rhombohedral α-Fe2O3 nanoparticles exhibited good sensor capability toward H2O2 with a linear response in the concentration range of 2–20 mM.

Ag-Si codoped TiO2 nanoparticles were successfully synthesized via a rapid and energy frugal microwave-assisted solvothermal method. The obtained materials were characterized by XRD, BET, TEM, XPS, and UV-Vis DRS. These characterizations revealed that the obtained materials possessed good crystallinity, small particle size and large surface area. In this system, silicon could enter into the crystal lattice of TiO2, leading to smaller particle size and larger surface area compared to pure TiO2; silver dispersed on the surface of TiO2 particles, contributing to the visible light response and benefiting the efficient separation of photoelectrons and holes. Thus, the synthesized materials should achieve enhanced photoactivity under visible light irradiation, and that was evaluated by the decomposition of Rhodamine B in the aqueous solution. It was found that the Ag-Si codoped TiO2 photocatalyst exhibited higher photocatalytic activity compared with pure TiO2 and Ag or Si doped TiO2. The doping amount of the silver showed significant effect on the photocatalytic activity, and the optimal activity was achieved with Ag content of 1 mol%.

a b s t r a c t Under the influence of thiocyanate anions (SCN−) and cetyltrimethyl ammonium bromide (CTAB), NiS flower-like architectures were successfully synthesized by a one-step hydrothermal method. The syn- thesized flower-like architectures, with a multilayered and highly ordered texture, have diameters of several micrometers. X-ray powder diffraction (XRD) shows that the NiS flower-like architectures are rhombohedral crystalline. On the basis of condition-dependent experiments, the diffusion-limited aggre- gation (DLA) model and cage effect were used to explain the growth process of rhombohedral crystalline NiS flower-like architectures. Magnetic measurements showed that the coercivity (Hc) of the as-obtained NiS flower-like architectures was 102.14 Oe.

With the presence of SCN − anions, Ni(OH) 1.4 (SO 4 ) 0.3 nanoribbons have been successfully synthesized by one-step hydrothermal method. The synthesized nanoribbons are with width of several tens of nanometers and length of several tens of micrometers. X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) analysis revealed that the products were mainly dominated by (0 0 2) lattice plane. On the basis of condition-dependent experiments, a recrystallization–oxidation-split growth mechanism was proposed to explain the formation process of the Ni(OH) 1.4 (SO 4 ) 0.3 nanoribbons. As-synthesized products showed a photocatalytic capability under the irradiation of ultraviolet light for the decomposition of methyl orange as a probe reaction.

α-Fe2O3 particles with various morphologies, including micro-doublesphere, tetrakaidecahedron and nanoparticles-aggregated micro-ellipsoid, were successfully synthesized via an octadecylamine-assisted hydrothermal method. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results indicate that the presence of octadecylamine played a crucial role in morphology evolution by selective crystal adsorption. The protonated octadecylamine increased the pH value that accelerated nucleation, and the long alkyl groups of octadecylamine acted as an adsorption inhibitor to retard the growth of nanoparticles. The as-prepared α-Fe2O3 particles exhibited higher remanent magnetization and coercivity than other α-Fe2O3 particles of similar size. These properties should be attributed to the superstructure and the shape anisotropy of the synthesized particles.

Octadecahedral alpha-Fe2O3 nanoparticles were hydrothermally synthesized in the presence of formamide. These octadecahedral alpha-Fe2O3 nanoparticles have a threefold axis and are enclosed by twelve dominant {112} facets and six {104} facets. In comparison with the {104} facets, the sterically less hindered {112} facets induced the selective adsorption of formamide more easily, which resulted in the gradual increase in the amount of {112} facets by decreasing the amount of {104} facets with increasing formamide. The coercivity (Hc) of these octadecahedral particles increased successively as the aspect ratio (c/a) increased. The sensing capability of these particles toward H2O2 was investigated, and the response currents of the particles dominated by {112} facets showed a linear relationship with a concentration of H2O2 in the range from 40 mu M to 6.66 mM in different stages. Octadecahedral alpha-Fe2O3 nanoparticles were hydrothermally synthesized in the presence of formamide. These octadecahedral alpha-Fe2O3 nanoparticles have a threefold axis and are enclosed by twelve dominant {112} facets and six {104} facets. In comparison with the {104} facets, the sterically less hindered {112} facets induced the selective adsorption of formamide more easily, which resulted in the gradual increase in the amount of {112} facets by decreasing the amount of {104} facets with increasing formamide. The coercivity (Hc) of these octadecahedral particles increased successively as the aspect ratio (c/a) increased. The sensing capability of these particles toward H2O2 was investigated, and the response currents of the particles dominated by {112} facets showed a linear relationship with a concentration of H2O2 in the range from 40 mu M to 6.66 mM in different stages.

SiO2 hollow spheres with movable Fe3O4 core were obtained by exposing the pre-synthesized Fe3O4\SiO2 particles (with an adsorption interlayer of ethylene glycol) under the irradiation of electron beam inside transmission electron micrograph (TEM). In the formation process, the evaporation of adsorbed ethylene glycol and the evolution of amorphous SiO2 layer played important roles, and that should be attributed to the high temperature and trapped charges induced by the irradiation of electron beam. This work provided a new route to obtain particles with movable core structure and extended the applications of electron beam.

To obtain a recyclable surface-enhanced Raman scattering (SERS) material, we developed a composite of Fe3O4\SiO2\Ag with core\shell\particles structure. The designed particles were synthesized via an ultrasonic route. The Raman scattering signal of Fe3O4 could be shielded by increasing the thickness of the SiO2 layer to 60 nm. Dye rhodamine B (RB) was chosen as probe molecule to test the SERS effect of the synthesized Fe3O4\SiO2\Ag particles. On the synthesized Fe3O4\SiO2\Ag particles, the characteristic Raman bands of RB could be observed when the RB solution was diluted to 5 ppm (1×10−5 M). Furthermore, the synthesized particles could keep their efficiency till four cycles.

Despite significant advances in iron oxide nanoparticles, it is still a challenge to synthesize regular polyhedral single-crystalline α-Fe 2 O 3 particles because the surface energies of several low-index planes are fairly similar. In the work presented here, well-dispersed and single-crystalline dodecahedral and octodecahedral α-Fe 2 O 3 particles are synthesized by a facile hydrothermal method with the aid of F - anions. The crystalline structure of the polyhedral particles is disclosed by various characterization techniques. The dodecahedral particles are of hexagonal bipyramidal shape and enclosed by twelve equivalent (101) planes. The octodecahedral particles are formed by adding six equivalent (111) planes on the two tips of a dodecahedral particle, that is, they are enclosed by twelve (101) planes and six (111) planes. The existence of F - anions plays a crucial role in the control of polyhedral particle shape. The function of F - anions in the shape formation ofthe polyhedral particles is proposed as follows: 1) A high concentration of exposed Fe 3+ cations induces preferential adsorption of F - anions on the (100) plane and leads to the slowest growth along the [100] direction. When the concentration of F - anions is higher than 24 mM, a stable speed ratio of growth along the [001] and [100] directions results in the exposure of (101) planes. 2) With a lower concentration of F - anions, six symmetrical (111) planes with low concentration of exposed Fe 3+ cations are present at the tops of a dodecahedral particle to form an octodecahedron. Furthermore, the dodecahedral and octodecahedral α-Fe 2 O 3 particles show much stronger magnetism than the previously reported α-Fe 2 O 3 nanostructures, having coercivities of 4986 Oe and 6512 Oe, respectively. Such high coercivities are attributed to a large local magnetic anisotropy, which might be induced by the polyhedron with equivalent crystallographic planes and/or the presence of F - anions.

Plasma equilibrium reconstruction plays an important role in the tokamak plasma research. With a high temporal and spatial resolution, the POlarimeter-INTerferometer (POINT) system on EAST has provided effective measurements for 102s H-mode operation. Based on internal Faraday rotation measurements provided by the POINT system, the equilibrium reconstruction with a more accurate core current profile constraint has been demonstrated successfully on EAST. Combining other experimental diagnostics and external magnetic fields measurement, the kinetic equilibrium has also been reconstructed on EAST. Take the pressure and edge current information from kinetic EFIT into the equilibrium reconstruction with Faraday rotation constraint, the new equilibrium reconstruction not only provides a more accurate internal current profile but also contains edge current and pressure information. One time slice result using new kinetic equilibrium reconstruction with POINT data constraints is demonstrated in this paper and the result shows there is a reversed shear of q profile and the pressure profile is also contained. The new improved equilibrium reconstruction is greatly helpful to the future theoretical analysis.

Zr/ZrH 2 particles with irregular morphologies and broad size distribution were uniformly coated with acicular α-FeOOH crystal grains via a facile route without using polymers or surfactants. The as-synthesized material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), UV–vis diffusion reflection (UV–vis) and Raman spectrometry. Based on these characterizations, the synthesis mechanism was explained in terms of combined heterogeneous nucleation and solid state transformation reaction. The presence of α-FeOOH coating greatly changed the combustion behavior of Zr/ZrH 2 particles: the combustion lasting time decreased from 32 s for un-coated Zr/ZrH 2 particles to 0.2 s for coated particles while the maximum temperature in the combustion process increased from 1510 °C to 2036 °C.

Spindle porous iron nanoparticles were firstly synthesized by reducing the pre-synthesized hematite (α-Fe 2 O 3 ) spindle particles with hydrogen gas. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption isotherms and vibrating sample magnetometry (VSM). A lattice shrinkage mechanism was employed to explain the formation process of the porous structure, and the adsorbed phosphate was proposed as a protective shell in the reduction process. N 2 adsorption/desorption result showed a Brunauer–Emmett–Teller (BET) surface area of 29.7 m 2 /g and a continuous pore size distribution from 2 nm to 100 nm. The magnetic hysteresis loop of the synthesized iron particles showed a saturation magnetization of 84.65 emu/g and a coercivity of 442.36 Oe at room temperature.

Magnetite (Fe3O4) nanotubes were prepared by reducing synthesized hematite (α-Fe2O3) nanotubes in 5% H2+95% Ar atmosphere, and then maghemite (γ-Fe2O3) nanotubes were obtained by re-oxidizing the Fe3O4 nanotubes. The nanotube structure was kept from collapsing or sintering throughout the high temperature reducing and re-oxidizing processes. The coercivities of the Fe3O4 and γ-Fe2O3 nanotubes synthesized were found to be 340.22 Oe and 342.23 Oe, respectively, both higher than other nanostructures with the same phase and of similar size. Both adsorbed phosphate and the nanotube structure are considered responsible for this high coercivity.

Zirconium particles with irregular morphology and broad size distribution were uniformly coated by spherical α-Fe2O3 crystal grain via a facile route without polymer or surfactant as directing agents. The synthesized α-Fe2O3/Zr composite particles were characterized by X-ray diffraction, scanning electron microscopy, energy dispersion X-ray, UV–vis spectroscopy and Raman spectroscopy. The synthesis mechanism could be explained by cooperated heterogeneous nucleation and solid state transformation reaction. The combustion properties of α-Fe2O3/Zr composite particles were investigated. Compared with Zr particles, the combustion lasting time decreased from 16 s of Zr particles to 0.13 s of α-Fe2O3/Zr composite particles, and the top point of temperature reached in combustion increased from 2004 °C of Zr particles to 2378 °C of α-Fe2O3/Zr particles.

Si-doped TiO2 nanoparticles were prepared via a solvothermal method and were sensitized by the Fe-quinoline complexes (HQSI) to improve the visible light photocatalytic activity. The used HQSI had a narrow band gap of 1.54 eV and showed strong visible light absorption. HQSI can transfer photoelectrons to the conduction band of TiO2 and be regenerated by the electron injection from Rhodamine B. After sensitization, the Si-doped TiO2 exhibited stronger absorption in the visible region and showed higher visible-light photocatalytic activity for the degradation of Rhodamine B in an aqueous solution than the simple Si-doped TiO2 and sensitized commercial TiO2.

Single-crystal α-Fe(2)O(3) hexagonal nanorings with hexagonal inner hole were synthesized under the stepwise influence of different anionic ligands (F(-) and SCN(-)). This is a new method to design and modify crystal structures of transition metal oxide nanoparticles.

A simple low-cost hydrothermal method has been developed to fabricate uniformly dispersed octahedral Fe3O4 nanoparticles with tunable size. The particle size can be reduced to 20–30 nm under the effect of phosphate, meanwhile, the edetate disodium can improve the dispersivity of particles. High-resolution transmission electron microscope showed that the octahedral Fe3O4 nanoparticle was enclosed by eight (111) planes. Octahedral γ-Fe2O3 nanoparticles were obtained by reoxidizing the as-synthesized Fe3O4 nanoparticles. The microwave absorption properties of the octahedral Fe3O4 and γ-Fe2O3 nanoparticles were measured in the frequency range of 2–18 GHz. A minimum reflection loss of −28 dB was observed at 8.6 GHz for octahedral Fe3O4 nanoparticles.

The title nanoribbons are hydrothermally synthesized in the presence of SCN- anions by dissolving NaSCN, Ni(NO3)2, and NaOH in water under ultrasonic radiation followed by heating (autoclave, 220 °C, 24 h).