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A composite system consisting of aminosilicate (APS) functionalized-fullerene quantum dots (C60 QDs) and bismuth vanadate (BiVO4-APS-C60) has been developed via a facile one-step hydrothermal process. The structural analysis by XRD revealed that the integrated QDs have not affected the crystal structure of the host BiVO4, while the XPS studies showed that these QDs have been integrated via the Bi-V-O-Si-C network. The optical studies indicated that both the C60 and APS-C60 QDs have hardly influenced the optical absorption properties of the composite system. On the other hand, the dispersion of aminosilicate functionalized-QDs considerably reduced the aggregation in the layers and yielded a few nanometer thick BiVO4 layers due to their inter-layer occupancy as seen from their high-resolution TEM images. The photoluminescence, photocurrent and electrochemical impedance studies showed that the integration of APS-C60 QDs greatly improved the photoactive properties of the composite by effectively enhancing the charge recombination resistance, charge separation and transfer process between the integrated materials and surroundings. As a result, BiVO4-APS-C60 composites showed the enhanced photocatalytic efficiency towards degradation of ciprofloxacin (CIP) molecules under solar light irradiation as compared to that of bare-BiVO4 and BiVO4-C60.

This work demonstrated the promise of using industrial-grade sugar syrups derived from corn and wood, i.e., high fructose corn syrup (HFCS), glucose corn syrup (GCS) and wood-based sugar (TMP-Bio Sugar), as cheaper and competitive feedstocks for 5-HMF production using niobium phosphate as a heterogeneous solid acid catalyst in a biphasic continuous-flow tubular reactor. 5-HMF yield as high as 53.1% with 100% sugar (glucose and fructose) conversion was obtained from catalytic dehydration of HFCS-90 (containing 90 wt% fructose) at 150 °C, with feed concentration of 200 mg/ml (glucose and fructose) and aqueous to organic phase ratio of 1:5 (v/v). Catalyst stability with time was tested over 20 h of continuous-time on stream, and the reusability of the catalyst was studied after in-situ regeneration of the used catalyst by calcination in the air for removing the deposited humins and coke on the surface of the catalyst particles. The regenerated catalyst showed good activity with almost constant selectivity, although at lower glucose conversion and reduced 5-HMF yield compared to the fresh catalyst, indicating that the in-situ regeneration process could recover a part of the acid sites on the catalyst surface. The produced humins during the reaction were characterized by Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA) and elemental analysis (CHNS). The results showed high aromaticity and the presence of a high degree of unsaturated compounds in the structure of humins.

Glyceryl monolaurate (GML), as one of widely used industrial chemicals, can be synthesized via Fischer esterification of lauric acid (LA) and glycerol (GL). In this work, we screened boric acid-based deep eutectic solvent (DES) formed from tetrapropylammonium bromide (TPAB) and boric acid to intensify the selective Fischer esterification through conductor-like screening model for realistic solvents (COSMO-RS) theory. The solid liquid equilibrium (SLE) phase behavior, hydrogen bond formation process, and thermal stability of the DES were characterized by differential scanning calorimetry (DSC), Fourier transform infrared spectrometry (FT-IR), and thermogravimetric analyzer (TGA). The results verified that equimolar TPAB and boric acid formed DES [TPAB:B(OH)3] with the lowest freezing point and very good thermal stability could efficiently intensify the Fischer esterification of GL and LA to GML. The hydrogen bond accepter TPAB of the DES made the esterification system homogeneous, which promoted the selective esterification process. In addition, the hydrogen bond donor B(OH)3 of the [TPAB:B(OH)3] combined with diol unit of GL to cyclic boric esters and led to a special selective space effect, which also improved the selectivity to GML. Thus, the esterification intensified of GL and LA by 20 wt% DES achieved GML selectivity of 85.7 % and yield of 76.4 % under the optimal reaction conditions. The esterification kinetics suggested the reaction followed pseudo-second-order model and the reaction activation energy was 33.98 kJ mol−1, similar to and/or lower than those reported works. Furthermore, DES and unreacted glycerol were readily recovered and reused through temperature controlled gravity-based separation due to the ability of homogeneity under reaction conditions and splitting phase behavior during the DES recovery. The results can expand the boric acid-based DESs for other potential intensification applications.

High surface area cerium oxide was synthesized via the reverse microemulsion method and assessed for CO2 reduction to CO via reverse water gas shift. The resulted ceria nanoparticles (ca. 4 nm) were 100% selective to CO formation, while attaining a nearly equilibrium CO2 conversion at 600 °C. As compared to ceria synthesized by wet precipitation, the reverse microemulsion-synthesized ceria exhibited enhanced surface stability and a more stable catalytic performance (declining from 63% to 50% over 100 h on stream). No significant carbon formation was detected and a relatively small decline in conversion was related to the specific surface area reduction induced by the growth of ceria nanoparticles under the reaction conditions.

International audience; As nonclassical nucleic acid structures, G-quadruplexes (G4s) not only play important roles in gene regulation and stability maintenance, but are also widely used in nanotechnology. Structural diversity is one of the main factors explaining the popularity of G4s, but a comprehensive and integrated study of different factors determining G4 structural versatility is currently lacking. Herein, starting from a common G4 sequence, (G 3 T) 3 G 3 , as the parent chain, and then taking advantage of G4 versatility, we present a variety of strategies to control G4 structure, based on the regulation of loop length and flanking sequences, cation (type and concentration), and molecular crowding. These strategies allow us to convert the G4 topology from parallel to hybrid, to antiparallel, and then back to parallel. Such structural diversity reveals the coding regulation ability of G4 structures, with potential applications in nanotechnology.

The near-infrared (NIR) persistent luminescence materials (PLMs) can remain long-lasting luminescence after removal of the excitation light, which permits bioimaging with high sensitivity owing to the absence of background fluorescence interference from in situ excitation. Recently, the NIR PLMs have aroused intensive research interest in bioimaging. However, the optimal excitation wavelength of current NIR PLMs is located in the ultraviolet region with shallow tissue penetration, making it difficult to activate effectively in vivo, and seriously hindering their further application in bioimaging. Herein, we report a novel kind of Cr3+ ions and Y3+ ions co-doped NIR PLM, Zn1.3Ga1.4Sn0.3O4:Cr3+,Y3+ (ZGSCY), which emits NIR persistent luminescence at 696 nm. Compared with Zn1.3Ga1.4Sn0.3O4:Cr3+ (ZGSC) excited by the light with a wavelength in the biological window (>650 nm), after being co-doped with Y3+ ions, the NIR persistent luminescence performance of ZGSCY is significantly improved because of the increase of trap concentration in the matrix. In addition, we synthesized ZGSCY nanoparticles (NPs) by the combustion method, which exhibit excellent optical properties after being excited by the light with a wavelength in the biological window. After surface modification with PEG, the ZGSCY NPs present low cytotoxicity. Notably, due to the co-doping of Y3+ ions, the signal-to-noise ratio (SNR) of ZGSCY NPs in vivo imaging is about 1.8 times higher than that of the ZGSC NPs. Furthermore, the rechargeable in vivo imaging and passive tumor-targeted imaging are successfully achieved by activating with a light-emitting diode (LED, 659 nm) after intravenous injection of ZGSCY. Thus, this kind of NIR PLM with high excitation efficiency performance in the biological window is expected to promote its biomedical application in deep tissues.

In very recent years, ultraviolet (UV) persistent luminescent materials (PLMs) have attracted widespread attention due to their potential biological applications. However, owing to the lack of suitable emitters and hosts, the design and development of excellent UV PLMs remain challenging. Here, we report a new Gd-based PLM NaGdGeO4:Bi3+ with super-long UVA persistent luminescence (PersL). By further co-doping Li+ ions to increase the concentration of traps, the UVA PersL intensity of NaGdGeO4:Bi3+ is increased by 5.5 times. The optimal NaGdGeO4:Bi3+,Li+ exhibits excellent UVA PersL and can persist for more than 200 h. Moreover, the phosphor NaGdGeO4:Bi3+,Li+ also exhibits photostimulated property with a red LED or NIR laser excitation after the long-term decay, and can be activated by X-ray. This promising Gd-based UVA PLM is expected to have potential applications in biomedicine through triggering photocatalysts or photosensitizers by its UVA PersL to achieve photodynamic therapy and its potential ability of magnetic resonance (MR) imaging due to Gd3+ ions as MR imaging probe containing in the host NaGdGeO4.

Synthetic two-dimensional (2D) mono-elemental crystals, namely X-enes, have recently emerged as a new frontier for atomically thin nanomaterials with on-demand properties. Among X-enes, antimonene, the β-phase allotrope of antimony, is formed by atoms arranged in buckled hexagonal rings bearing a comparatively higher environmental stability with respect to other players of this kind. However, the exploitation of monolayer or few-layer antimonene and other 2D materials in novel opto-electronic devices is still hurdled by the lack of scalable processes. Here, we demonstrated the viability of a bottom-up process for the epitaxial growth of antimonene-like nanocrystals (ANCs), based on a Metal-Organic Chemical Vapor Deposition (MOCVD) process, assisted by gold nanoparticles (Au NPs) on commensurate (1 1 1)-terminated Ge surfaces. The growth mechanism was investigated by large- and local-area microstructural analysis, revealing that the etching of germanium, catalyzed by the Au NPs, led to the ANCs growth on the exposed Ge (1 1 1) planes. As a supportive picture, ab-initio calculations rationalized this epitaxial relationship in terms of compressively strained β-phase ANCs. Our process could pave the way to the realization of large-area antimonene layers by a deposition process compatible with the current semiconductor manufacturing technology.

Some organic molecules encapsulate solvents upon crystallization. One class of compounds that shows a high propensity to form such crystalline solvates are tetraaryladamantanes (TAAs). Recently, tetrakis(dialkoxyphenyl)-adamantanes have been shown to encapsulate a wide range of guest molecules in their crystals, and to stabilize the guest molecules against undesired reactions. The term ‘encapsulating organic crystals’ (EnOCs) has been coined for these species. In this work, we studied the behavior of three TAAs upon exposition to different guest molecules by means of sorption technique. We firstly measured the vapor adsorption/desorption isotherms with water, tetrahydrofuran and toluene, and secondly, we studied the uptake of methane on dry and wet TAAs. Uptake of methane beyond one molar equivalent was detected for wet crystals, even though the materials showed a lack of porosity. Thus far, such behavior, which we ascribe to methane hydrate formation, had been described for porous non-crystalline materials or crystals with detectable porosity, not for non-porous organic crystals. Our results show that TAA crystals have interesting properties beyond the formation of conventional solvates. Gas-containing organic crystals may find application as reservoirs for gases that are difficult to encapsulate or are slow to form crystalline hydrates in the absence of a host compound. Wet tetraaryladamantane crystals take up methane in form of methane hydrate structure I, even though they appear non-porous to argon., Deutsche Forschungsgemeinschaft, University of Stuttgart, Projekt DEAL

The interaction and nature of surface sites for water and methanol sorption on MFI-type zeolites and mesoporous SBA-15 were investigated by solid-state NMR spectroscopy and correlated with the desorption enthalpies determined via TGA/DSC. For siliceous Silicalite-1, 29Si CPMAS NMR studies support stronger methanol than water interactions with SiOH groups of Q3-type. On siliceous SBA-15, SiOH groups of Q2-type are accompanied by an enhanced hydrophilicity. In aluminum-containing Na-ZSM-5, Na+ cations are strong adsorption sites for water and methanol as evidenced by 23Na MAS NMR in agreement with high desorption enthalpies of ΔH = 66-74 kJ/mol. Solid-state NMR of aluminum-containing Na-[Al]SBA-15, in contrast, has shown negligible water and methanol interactions with sodium and aluminum. Desorption enthalpies of ΔH = 44-60 kJ/mol hint at adsorption sites consisting of SiOH groups influenced by distant framework aluminum. On H-ZSM-5, Brønsted acidic OH groups are strong adsorption sites as indicated by partial protonation of water and methanol causing low-field shifts of their 1H MAS NMR signals and enhanced desorption enthalpies. Due to the small number of Brønsted acid sites in aluminum-containing H-[Al]SBA-15, water and methanol adsorption on this material is suggested to mainly occur at SiOH groups with distant framework aluminum species, as in the case of Na-[Al]SBA-15., Deutsche Forschungsgemeinschaft (DFG), Projekt DEAL

Electrochemical CO2 reduction to higher-value hydrocarbons beyond C1 products has attracted much attention recently. Single-atom catalysts (SACs) are regarded as promising CO2 reduction electrocatalysts. However, most SACs only show activity to C1 products. In this work, we considered the activity and the synergetic effect of dual active sites for metal SACs supported on graphitic carbon nitride (g-C3N4) as CO2 reduction electrocatalysts. Density functional theory (DFT) calculations are employed. First, by using the adsorption energies of CO* on the metal site and that of H* on the nitrogen site as bi-descriptors, we predicted seven out of 14 metal centers have the propensity to generate beyond CO products. To further evaluate the catalyst activity on beyond CO product formation, we established reaction pathways towards ethylene through M/N or M/C. Ru has the best performance (the limiting potential is −0.90 V) by taking M/N as active sites. A dual volcano-shaped plot is built up based on the CO adsorption energies on metal sites, which can be used to indicate whether M/C or M/N shows better performance for a specific metal center. Our work shed light on developing criteria to guide the design of CO2 reduction electrocatalysts with dual active sites.

The catalysts with higher efficiencies at mild reaction conditions are of great importance for development of ammonia synthesis with zero CO2 emissions. Here, we report, highly efficient mixed oxide supported Ru catalysts for ammonia synthesis. MgO-CeO2 supports with different Mg and Ce contents were fabricated and loaded with 1% Ru using impregnation technique. MgO-CeO2 supported Ru catalysts demonstrated efficient ammonia synthesis. Mixed oxide MgO-CeO2 supported catalysts even with higher MgO content were established with comparable ammonia synthesis yields to that obtained from pure CeO2 supported catalyst under same reaction conditions. The catalytic activity was highly dependent on the texture and physical properties of the catalysts. Presence of highly dispersed Ce and Ru has been suggested as a possible explanation for the higher yield of ammonia obtained from Ru/MgO-CeO2 catalysts having Ru selectively deposited on CeO2.

Even though catalyst loading is one of the first crucial steps in organic and inorganic catalytic reactions, it has not been frequently discussed or improved to date. In particular, when a solid catalyst is added to an oxygen- and moisture-sensitive reaction mixture, a carefully tuned process to ensure an inert atmosphere (under nitrogen or argon) is required. Although gloveboxes are nowadays considered to be a universal solution, it is still associated with unsolved problems, such as high cost, high space consumption, difficult temperature control, and handling difficulties on account of the gloves. Herein, we report a recently developed simple apparatus that enables the addition of a solid without opening the reaction vessel. This solid-addition funnel drastically improved the yield (from trace to 64%) and the reproducibility of our original glycosylation reaction.

A Pd-catalyzed carbonylative double cyclization approach to a novel class of S,O-bicyclic heterocycles is presented. It is based on the reaction between readily available 5-(methylthio)pent-1-yn-3-ols with CO in the presence of the PdI2/KI catalytic system carried out under oxidative conditions with oxygen as external oxidant. The process takes place through an ordered sequence of steps involving an initial 5-exo-dig S-cyclization (by intramolecular nucleoplilic attack by the thiomethyl group to the triple bond activated by coordination to the palladium center), followed by S-demethylation (by attack by the iodide anion), carbon monoxide insertion, O-cyclization (by intramolecular nucleophilic displacement of the hydroxyl group to the ensuing acylpalladium intermediate), and Pd(0) reoxidation. The method allows the construction of previously unreported 6,6a-dihydrothieno[3,2-b]furan-2(5H)-ones starting from simple substrates (5-(methylthio)pent-1-yn-3-ols and CO) with the formation of 3 new bonds and two cycles in one step, and has been successfully applied to the synthesis of variously substituted products (57–81 %, 17 examples).

Synthesis of well dispersed and strongly interacted Ni-based catalysts benefits the catalytic performances in high-temperature reactions. Significant works have been reported on the roles of calcination environments. During calcination of the catalyst precursors (pretreatment or activation in other cases), the type of atmospheres greatly affects the size, metal-support interaction (MSI) and surface properties of Ni-based catalysts, influencing the catalytic performances. In this review, it is the first time to comprehensively summarize the influences of three categories of atmospheres – oxidative (air, O2 and CO2), inert (N2, Ar) and reductive (H2, NO, N2O and CO) gases, on the physiochemical properties of Ni-based catalysts, which provides a facile and general strategy to optimize the formation of metal nanoparticles on the supports.

International audience; The mechanisms of H 2 dissociation on three stoichiometric anatase TiO 2 terminations, (001), (100) and (101), have been studied by means of density functional theory (PBE+U) calculations. A two-step process was considered: first, H 2 dissociation into H + and H − pair, and second the H − species migrates to a neighboring O site, transferring the electrons to the substrate. On (001), it shows the lowest activation barriers for hydrogen dissociation, 0.37 eV, whereas the highest value was found on (101), 0.98 eV. For hydrogen transfer from Ti to near O, the activation barriers are higher (from 1.10 to 2.37 eV), which indicates the dissociation step is kinetically more favorable than the H transfer process, although the latter is thermodynamically more favorable. Electronic structure, vibrational frequency analysis as well as temperature effects are studied to characterize the reactivity. The relationship between electronic structure, geometry and reactivity is analyzed by means of reactivity descriptors, and the results are compared with ceria and rutile TiO 2 facets.

The production of hydrogen as a clean energy source by a facile method are major concern and promising research area now a days. The electrolysis of water to generate hydrogen and oxygen as a fuel are challenging renewable energy technology. To develop a highly efficient low-cost non-noble metal-based catalyst for hydrogen evolution reaction (HER) is essential and urgent need. Thus, the present work describes a facile synthetic approach to develop suitable cost effective electrocatalyst for water splitting application. It deals one-pot synthesis of low-cost transition metal based ternary metal sulphide (BMS) CuCo2S4, CuMn2S4, CuNi2S4, and CuZn2S4 microspheres as electrocatalyst to generate hydrogen from water. The physical characterization of synthesized electrocatalyst were performed by powder x-ray diffractometer (PXRD) and Raman spectroscopy. The morphological characterization of synthesized electrocatalyst were done by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) however the elemental mapping analysis was done by energy-dispersive X-ray spectroscopy (EDX). The electrochemical measurements were performed in 0.5 M H2SO4 acidic medium on 3-electrode polymer electrolyser membrane water (PEMW) system. The lowest onset and overpotential values have been observed as 61 and 79 mV, respectively in the case of CuCo2S4 micro-sphere. However, the Tafel slope values of CuCo2S4, CuMn2S4, CuNi2S4, and CuZn2S4 electrocatalysts were calculated 121, 115, 102 and 41 mV respectively. On the basis of obtained electrochemical characterization results, CuCo2S4 has been revealed better electrocatalyst under acidic media. This study opens a new direction to consider low-cost transition metal based ternary microspheres as electrocatalyst to produce hydrogen during water electrolysis.

Catalysis today 376, S0920586121002856 (1-10) (2021). doi:10.1016/j.cattod.2021.06.018, The objective of this research was to investigate how the photocatalytic activity of pure TiO$_2$ can be improved bySnO$_2$ modification. Different molar ratios of tin to titanium were prepared. The correlation between tin concentration and structural properties was investigated to explain the mechanism of photocatalytic efficiency and to optimize the synthesis conditions to obtain enhanced activity of the SnO$_2$-modified TiO$_2$ photocatalysts under UV-irradiation. The SnO$_2$-modified TiO$_2$ photocatalysts were prepared by a low-temperature sol-gel method based on organic tin and titanium precursors. The precursors underwent sol-gel reactions separately to form SnO$_2$-TiO$_2$ sol. The sol-gels were deposited on a glass substrate by a dip-coating technique and dried at 150 °C to obtain the photocatalysts in the form of a thin film. To test the thermal stability of the material, an additional set of photocatalysts was prepared by calcining the dried samples in air at 500 °C. The photocatalytic activity of the samples was determined by measuring the degradation rate of an azo dye. An increase of up to 30% in thephotocatalytic activity of the air-dried samples was obtained when the TiO$_2$ was modified with the SnO$_2$ in a concentration range of 0.1–1 mol.%. At higher SnO$_2$ loadings, the photocatalytic activity of the photocatalystwas reduced compared to the unmodified TiO$_2$. The calcined samples showed an overall reduced photocatalyticactivity compared to the air-dried samples. Various characterization techniques (UV-Vis, XRD, N2-physisorption,TEM, EDX, SEM, XAS and photoelectrochemical characterization) were used to explain the mechanism for the enhanced and hindered photocatalytic performances of the SnO$_2$-modified TiO$_2$ photocatalysts. The results showed that the nanocrystalline cassiterite SnO$_2$ is attached to the TiO$_2$ nanocrystallites through the Sn-O-Ti bonds. In this way, the coupling of two semiconductors, SnO$_2$ and TiO$_2$, was demonstrated. Compared to single-phase photocatalysts, the coupling of semiconductors has a beneficial effect on the separation of charge carriers, which prolongs their lifetime for accessibility to participate in the redox reactions. The maximum increase in activity of the thin films was achieved in the low concentration range (0.1–1 mol.%), which means that an optimal ratio and contact of the two phases is achieved for the given physical parameters such as particle size, shape and specific surface area of the catalyst., Published by Elsevier, Amsterdam

In this study, β-blocker metoprolol was degraded by photocatalysis and photo-Fenton catalyzed by doped TiO2. The effect of two main variables was elucidated, content and type of doping cation (Fe or Cu). The catalysts were synthesized by Evaporation-Induced Self-Assembly (EISA) method and their performance was compared with typical Degussa P25. All synthesized materials were found to be mesoporous with a specific surface in the range of 121–242 m2/g, they all exhibited anatase phase, and crystallites in the range of 6–10 nm. The use of X-ray photoelectron spectroscopy (XPS) allowed to establish not only the presence of the expected Ti4+ but also Ti3+ species. Cu2+ and Fe3+ species were also identified in the doped catalysts. It was found that the addition of Cu and Fe diminished the energy band gap of synthesized TiO2, from 3.20 eV to 2.58 and 2.64, respectively. The content of Cu is directly correlated with this effect. In photocatalysis, the doping of TiO2 did not have an effect of metoprolol degradation rate. This was improved, however, approximately 60% by the synthesized TiO2 compared to Degussa P25. On the other hand, the photo-Fenton-like process catalyzed by Cu-TiO2 exhibited the highest degradation (total removal) and mineralization extent (90%), being faster than the photocatalytic process and the UV-H2O2 system. Another difference between both methods, was the amount and type of intermediates generated. These were identified by LC-MS. Photo-Fenton catalyzed by Cu/TiO2 can be considered as an effective process with high oxidative power in the metoprolol degradation.

We developed bright yellow-emitting long persistent luminescence (LPL) materials Sr4Al14O25:Mn2+ and Sr4Al14O25:Mn2+,N (N = Zr4+, Ho3+, Er3+) by high temperature solid-state reaction. The addition of Zr4+, Ho3+ and Er3+ can regulate trap distributions and improve energy storage ability of the materials. The LPL performance of SAO:Mn2+,Ho3+ is optimal, considering LPL intensity and duration time. Bright LPL of SAO:Mn2+,Ho3+ can be observed for 3 h by naked eyes in dark after removing the excitation source. Profiles of LPL spectra are different from those of PL, because the two types of Mn2+ centers do not play equal parts in LPL and PL. Trap depths of TL peaks centered at 354 K (peak 1) and 455 K (peak 2) are 0.60 and 0.72 eV, respectively. And peak 1 at 354 K is the effective TL peak responsible for LPL. In SAO:Mn2+,Ho3+, Mn2+ ions doped in Al3+ sites serve as emitting centers, and positively charged Ho Sr · defects are the main effective trap centers. Finally, a feasible LPL mechanism of SAO:Mn2+,Ho3+ was proposed to clarify the generation process of LPL.

A series of novel red-emitting BaLiZn3(BO3)3:Eu3+ phosphors was synthesized through the high temperature solid state reaction method. The phase composition, crystal structure, morphology and photoluminescence property of the BaLiZn3(BO3)3:Eu3+ samples are systematically investigated. The phosphor can be efficiently excited by the near ultraviolet light (NUV) of 396 nm and blue light of 466 nm, and give out red light emission at 618 nm corresponding to the electric dipole transition (5D0→7F2). The optimal doping concentration of Eu3+ ions in BaLiZn3(BO3)3 is determined to be about 3 mol%, and the concentration-quenching phenomenon arise from the electric dipole–dipole interaction. The temperature dependent luminescence behavior of BaLiZn3(BO3)3:0.03Eu3+ phosphor exhibits its good thermal stability, and the activation energy for thermal quenching characteristics is calculated to be 0.1844 eV. The decay lifetime of the BaLiZn3(BO3)3:0.03Eu3+ is measured to be 1.88 ms. These results suggest that the BaLiZn3(BO3)3:Eu3+ phosphors have the potential application as a red component in white light emitting diodes (WLEDs) with NUV or blue chips.

In this work different variables that can affect the catalytic behavior of CuO-CeO2 supported on mesoporous silica (SBA-15 and SBA-16) were studied. The influence on the COPrOx activity of the relative concentration of the CuO and CeO2 active phase and different impregnation methods in mesoporous support was analyzed. The physicochemical characterization was performed EDS-SEM and TEM-STEM, N2 isotherms, X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The incipient wetness impregnation method (IWI) was the better alternative to introduce the active phases compared to solid state impregnation (SSI). In addition, the catalysts based on 2-D structure of SBA-15 were more active and selective than those based in 3-D SBA-16. In general, the high surface area of the supports benefited the dispersion of CuO and CeO2 oxides nanoparticles. All catalysts displayed the preservation of the mesostructure and the formation of nanoparticles of active phases (less than 10 nm) detected by TEM. The best COPrOx catalyst, obtained from the SBA-15 fibers by IWI method, with a relative CuO concentration of 0.2, exhibited XCO ≥ 99% at 175 °C and above 90% in a wide window of temperatures. This catalyst showed an adequate performance in presence of CO2 and H2O and good recovery of CO conversion and selectivity. The analysis by XPS revealed that the majority species were Ce4+, however in some catalysts Ce3+ species are also present, which are associated with vacancies oxygen and favor the redox process. In addition, Cu2+ and Cu+ species are present, the latter recognized as a key site of CO adsorption in the reaction mechanism.

In this study, molten salt was used as a solvent for calcium (Ca) to let a reduction-diffusion (R-D) reaction occur below the melting point of Ca (1115 K), which is the lower limit temperature of the conventional R-D process. When the R-D reaction is conducted below 923 K with LiCl molten salt, submicron-sized TbCu7-type Sm–Fe powder is formed. The c/a ratio of the powder estimated by a synchrotron X-ray diffraction pattern is 0.8456, which is consistent with the Sm0.67Fe5.667(SmFe8.5) phase. An electron backscatter diffraction analysis reveals that single-crystalline TbCu7-type SmFe8.5 powder was synthesized for the first time.

The optical and thermal properties of a new class of fluoroindate glass with different erbium contents were investigated via Raman, transmission, and fluorescence spectroscopies, fluorescence decay curve analysis, and differential scanning calorimetry. The strength parameters of the samples were calculated using the Judd–Ofelt theory. The mid-infrared luminescence properties of erbium-doped fluoroindate glasses were studied, and a strong emission at 2.7 μm was obtained. Compared with the traditional ZBLAN glass, this glass has excellent emission properties, especially a longer fluorescence lifetime (7.09 ms) and larger emission cross-section (6.95 × 10−21 cm2) at 2.7 μm. The results indicate that fluoroindate glass is an attractive host for mid-infrared lasers and as a gain medium for optical amplifier applications.

In this paper, the effect of Ba2+ ions A-site doping LaFeO3 on structure, magnetic properties and microwave absorption properties was investigated by the sol-gel method. According to the TEM and FullProf refinement results, the structure of LaFeO3 changes from orthogonal (SG: Pnma) to cubic (SG: Pm-3m) when the Ba doping amount is x = 0.4. The SEM image shows that the particles size tends to decrease with the increase of Ba content. The production of weak ferromagnetism indicates that Ba doping has a significant effect on the magnetic properties of LaFeO3. The Neel temperature (TN) decreases significantly with the increase of Ba doping amount. An appropriate amount of Ba doping can effectively increase the dielectric and magnetic loss of LaFeO3 ceramics powders. The increase permittivity (e′) may have been attributed to the hopping spin of the electrons between the Fe3+ and Fe4+ ions with the Ba2+ ions doping. The minimum reflection loss (RL) of La0.9Ba0.1FeO3 at 6.72 GHz reached –30.04 dB, its effective bandwidth (RL ≤ –10 dB) is 2.1 GHz, and the matching thickness is only 3.2 mm. These results indicate that Ba doping can effectively control the microwave absorption properties of LaFeO3, especially in the C-band.

Neodymium naphthenate-loaded organic phase stripping using sodium oxalate solution was studied to explore the feasibility of synchronous rare earth-loaded organic phase stripping, rare earth precipitation, and blank organic phase saponification. Experimental results show that loaded organic phase stripping, rare earth precipitation, and blank organic phase saponification can be realized simultaneously. When using 20% excess of sodium oxalate over the stoichiometry with the volume ratio of organic phase to aqueous phase of 1:1 at 25 °C for 40 min, the single stage stripping rate and saponification value are about 40% and 0.29 mol/L, respectively. After 16 stages of countercurrent continuous stripping, the stripping rate of neodymium can reach 99%, the saponification value is 0.42 mol/L, the Nd3+ concentration in saponified organic phase is less than 0.0020 mol/L, and the main phase in precipitation is Nd2(C2O4)3∙10H2O. Afterwards, this saponified organic phase can be used in the extraction of NdCl3 solution, and then the loaded organic phases (neodymium naphthenate) with 0.16 mol/L Nd3+ can be retrieved. The morphology, particle size distribution, and composition of the Nd2(C2O4)3∙10H2O products are similar to those of the current direct precipitation products. The neodymium oxide prepared by continuous calcination of neodymium oxalate meets the national standard of China (GB/T 5240−2015). These results prove the feasibility of stripping neodymium naphthenate-loaded organic phase by using sodium oxalate solution. Sodium oxalate can serve as a stripping agent, a saponifier, and a precipitator, thereby simplifying rare earth extraction and separation. This study provides theoretical and technical support for the development of a novel method for rare earth extraction and separation.

The effect of gold nanoparticles supported on V2O5/TiO2 nanomaterials prepared by different routes and its activity in the CO oxidation at low temperature were studied. The catalysts were characterized by N2 physisorption, X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). This study showed that the sol-gel Au-V2O5/TiO2 material exhibited higher catalytic activity after a thermal treatment at 400 °C in hydrogen than Au-V2O5/NT nanotubes, Au-V2O5/P25 Evonik and V2O5/TiO2 nanomaterials. The sol-gel Au-V2O5/TiO2 catalyst was also more active than Au/TiO2. These results could be explained by the fact that the gold species (Au° and Au1+) improved the interaction between vanadium species and TiO2, allowing high vanadium oxidation states (from V3+ to V5+) through a charge transfer effect between the support surface and Au-VOx reactive species; the presence of monovanadate and Ti3+ species led to remarkable activity in the CO oxidation from 0 °C in comparison with Au/TiO2.

Pt and Ir catalysts (3% w/w) supported on Ce0.97Ru0.03O2 were synthesized and successfully tested in a low-temperature CO oxidation process. The CO oxidation was followed in-operation, by FTIR spectroscopy. The catalysts were characterized by SEM-EDS, HTEM, XRD, DRS UV–vis, XPS techniques and BET isotherms. It was found that Pt and Ir nanoparticles on Ce0.97Ru0.03O2 drastically improved the CO oxidation in comparison to CeO2, showing the best performance the Pt/ Ce0.97Ru0.03O2 system. From the FTIR studies, a route for CO oxidation was proposed. The CO oxidation pathway in Ce0.97Ru0.03O2 considers that CO was adsorbed at the Ce and Ru sites, while O2 is adsorbed on the surface oxygen vacancies, being activated by nearby Ru species. Subsequently, the activated oxygen reacts with CO linked to Ce and Ru to produce CO2. Also, Pt and Ir promotes oxygen vacancies, increasing the activation-adsorption of O2 and, consequently, the activity of the catalyst was improved.

Bastnaesite is an important rare earth mineral and is usually beneficiated by flotation. Sodium silicate is commonly used to depress calcium-bearing gangue minerals, however it can also depress bastnaesite when Ca2+ ions exist in the pulp. In this study, the effect of Ca2+ ions and sodium silicate individually or in combination on bastnaesite flotation was studied through micro-flotation, zeta potential, fluorescence spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements. Micro-flotation results show that the combination of Ca2+ ions and sodium silicate depresses bastnaesite more severely due to their synergistic effect. Zeta potential results show that the combination renders the surface potential of bastnaesite negatively shifted more significantly. Fluorescence spectroscopy shows that the combination decreases the surface hydrophobicity of bastnaesite more severely. XPS shows that the combination increases the adsorption of sodium silicate on bastnaesite by forming hydrophilic Ca-SiO3 precipitate, which causes more serious depression on bastnaesite flotation.

The present work reports the results of the lignin molecule degradation studies using nitrogen-doped ZnO photocatalysts supported on graphene oxide. Three different nitrogen precursors were used to achieve the nitrogen doping in ZnO, namely urea, ethylenediamine, and thiourea, using a microwave-assisted hydrothermal method. Our purpose is to demonstrate that different nitrogen precursors give rise to different amounts of doping in ZnO, which in turn, favorably affects their photocatalytic behavior. The synthesized compounds were tested on the lignin degradation reaction, under visible (Vis) and ultraviolet (UV) energy irradiation. Structural and physicochemical properties of prepared samples were investigated to provide explanation of the photocatalytic behavior observed in samples. XPS analyses were developed to determine differences in nitrogen content, as well to determine the proportion of N-N or O-Z-N binding in samples. Remarkable structural and photocatalytic differences were found for every sample as effect of the nitrogen precursor. Photocatalytic activity tests revealed that the percentage of lignin degradation under UV irradiation was 80 %; while using Vis energy the degradation value was 61 %.

Combining treatment and diagnosis, called theranostics, which is achieved within single nanoparticle is an ultimate goal of many studies. Herein, we developed a new nanotheranostic agent − Nd3+-sensitized upconversion nanoparticles core for dual modal imaging (i.e., upconversion luminescence imaging and magnetic resonance imaging) and antimony nanoshell for photothermal therapy (PTT). The core-shell-shell upconversion nanoparticles (NaYF4:Yb,Er@NaYF4:Yb,Nd@NaGdF4:Nd, named as UCNP) were firstly synthesized using thermal decomposition method and then were coated by antimony shell over the surface of UCNP using simple cost and time effective new method. Furthermore, the surface of UCNP@Sb nanostructures was modified with DSPE-PEG in order to enhance the water solubility and biocompatibility. The final nanotheranostic agent, named as UCNP@Sb-PEG, exhibits very low toxicity, good biocompatibility, very good photothermal therapeutic effect, and efficient upconversion luminescence (UCL) imaging of HeLa cells under only one laser (808 nm) irradiation. The antimony shell is quenching the upconversion emission in pristine nanotheranostic agent, but interestingly, the UCL intensity of the agent recovers progressively under 808 nm laser irradiation due to light induced degradability of antimony shell. Besides, high longitudinal relaxivity (r1) obtained from the experiment approves excellent potential of the nanotheranostic agent for T1-weighted magnetic resonance imaging application.

To upgrade the electric properties of lead-free piezoceramics, (1–x)(Ba0.98Ca0.02Ti0.94Sn0.04Zr0.02)O3-xY2O3 (abbreviated as (1–x)BCTSZ-xY, x = 0 mol%, 0.02 mol%, 0.04 mol%, 0.06 mol%, 0.08 mol% and 0.1 mol%) ceramics were successfully synthesized by traditional solid-state sintering method. The phase structure and microstructure of ceramics were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and piezoresponse force microscopyeramics (PFM). The electric properties of ceramics were researched through piezoelectric, dielectric and ferroelectric test instruments. The results show that all samples have pure perovskite structure and favorable electric properties. The optimal electric properties which especially include superior ferroelectric properties are gained when Y2O3 content is 0.06 mol% (d33 = 419 pC/N, kp = 52%, Tc = 89.5 °C, er = 26900, tanδ = 2.86%, Pr = 14.41 μC/cm2, Ec = 1.8 kV/cm). Moreover, the temperature-dependent dielectricity of samples shows apparent relaxor behavior under different frequencies. The Curie–Weiss law further proves that all samples are typical relaxor ferroelectrics, and the relaxor degree of samples decreases with increase of Y2O3 content. In conclusion, Y2O3 plays a significant role in enhancing electric properties of BCTSZ ceramics.

The application of Pr-Nd-Dy alloy in the field of high-performance Nd-Fe-B permanent magnet materials has great potential. The composition of the PrF3-NdF3-DyF3-LiF (PND-LiF) electrolyte system used in the production of Pr-Nd-Dy alloys, the distribution of F, Li, RE and other elements in the electrolyte and their occurrence state were studied in this paper. The effect of temperature and lithium fluoride addition on electrolyte conductivity was revealed using the continuous conductivity cell constant (CVCC) method. The thermal analysis method was used to study the influence of lithium fluoride addition on the electrolyte's liquidus temperature and the optimal process conditions for the production of Pr-Nd-Dy alloy were determined. The results show that the overall distribution of praseodymium neodymium fluoride and lithium fluoride is uniform in the electrolyte and dysprosium fluoride is distributed between praseodymium-neodymium fluoride and lithium fluoride. Praseodymium-neodymium oxide is embedded in praseodymium neodymium fluoride in spotty pattern. The electrolyte's conductivity is increased as the temperature and lithium fluoride addition are going up, while the liquidus temperature is going down with increasing lithium fluoride addition. The best electrolysis process conditions for the PND-LiF system to produce praseodymium neodymium dysprosium alloy are as follows: temperature 1050 °C, 15.56 wt% PrF3-62.22 wt% NdF3-11.11 wt% DyF3-11.11 wt% LiF.

A series of single Ce3+ doped and Ce3+ and Tb3+ co-doped Na2BaCa(PO4)2 (NBCP) phosphors have been synthesized by conventional solid-stated reaction method. The crystal structure, luminescence properties, thermal stability and energy transfer were carefully investigated. The Ce3+ is inferred to substitute the Ba2+ site in NBCP lattice. The color-tunable emission from blue to green is observed by adjusting Tb3+ concentration among NBCP: 0.03Ce3+, yTb3+ phosphors. The energy transfer behavior from Ce3+ to Tb3+ ions is both illustrated by co-doped PL spectra and decay curves. The energy transfer efficiency is as high as 91.5%. The mechanism of energy transfer is resonance type of dipole-dipole transition. In this work, the optimal phosphor exhibits the excellent thermal stability which keeps at 94.9% of that initial value at room temperature when temperature reaches to 150 ˚C. The Ce3+ and Tb3+ co-doped NBCP phosphor is a promising candidate for the application in the general lighting and display fields.

Pressure - and temperature-dependent luminescence properties of 3F3/2 → 4I9/2 transition of Nd3+:GdTaO4 were studied for potential applications in optical sensing. Two isolated emission lines correspond to 3F3/2(R2, 1) → 4I9/2(Z5) transitions, locates at 920 and 927 nm under ambient condition, are very sensitive to pressure with coefficients of −15.6 and −14.5 cm−1/GPa determined in a pressure range up to about 9 GPa. The luminescence intensity ratio between the two emission lines exhibits a large dependence with temperature in a range from 80 to 620 K, the corresponding temperature sensitivity at room temperature is similar to that of Nd3+:YAG. These advantages, together with the other observed features of high stable position relationship under pressure and low thermal shifts for the two emission lines indicate that, Nd3+:GdTaO4 is a promising candidate to be used as pressure and temperature sensors in the near-infrared spectral range.

Three binuclear rare earth based complexes combining RE ions with semirigid tricarboxylic ligand (H3L), namely, [RE2(L)2(DMF)4] [RE = Gd, Tb, and Dy; H3L = 5-((4-Carboxybenzyl)oxy)isophthalic acid; DMF = N,N-dimethylformamide] complexes, were fabricated successfully. The RE2(L)2(DMF)4 complexes consist of two central RE ions with the same coordination environment which were connected by two tridentate bridging carboxylic groups and two syn-syn bidentate bridging carboxylic groups originating from the L3– ligands to form the {RE2} dimeric unit. And thus provides the basis for further constructing a dense three-dimensional (3D) network structure. Moreover, the present RE2(L)2(DMF)4 complexes can be described by a topology diagram with the topology point symbol of {42·6}2{44·62·87·102}. Weak anti-ferromagnetic (AFM) coupling between the adjacent RE ions for all the present complexes is found according to the magnetic calculations. The observed significant cryogenic magnetocaloric effect (MCE) with the maximum magnetic entropy change − Δ S M m a x to be 26.3 J/(kg·K) with Δ H = 7 T in Gd2(L)2(DMF)4 complex makes it competitive for the cryogenic magnetic refrigerant. Moreover, the slow magnetic relaxation behavior at 0.2 T dc field with an obvious large U e f f / k = 45(4) K and τ 0 = 6.5(2)×10−10 s is confirmed in Dy2(L)2(DMF)4 complex. This work not only provides an effective strategy for obtaining molecular materials with high MCE, but also confirms that tricarboxylate ligands are the ideal choice for constructing stable high dimensional geometric structures.

In recent years, it has been found that the flexibility of structure and diversity of the components endow quite an amount of the organic-inorganic hybrid perovskites with novel properties, i.e., structural phase transitions. Considering the natural advantage of the perovskite-type structure in generation of stimuli-responsive or smart materials, we synthesized an organic-inorganic hybrid rare-earth double perovskite-type compound, (DMP)2LaRb(NO3)6 (DMP = N,N-dimethylpyrrolidinium cation, 1). It shows reversible phase transition at 219/209 K (heating/cooling). Variable-temperature single-crystal structure analysis and dielectric constant measurements reveal that the thermal vibrations of the polar cation guests and the distortion of the anionic cage-like framework are the origin of the phase transition. Meanwhile, the movement of polar cation in crystal lattices arouses dielectric transition between the low- and high-dielectric states, resulting in a switchable property of dielectric constant. The results reveal that the rare-earth double perovskite provides a promising platform for achieving switchable physical/chemical properties.

We proposed a direct in situ synthesis method for iron oxide nanoparticles (NPs) along with catalytic erformance upgrading of heavy crude oil (HCO). Our method compares the upgrading of a HCO where other iron oxide nanoparticles were synthesized by a traditional thermal decomposition method of organometallic compounds in the presence of stabilizing agents and solvents of high boiling points. Furthermore, the in situ nanoparticles were extensively characterized by XRD, Mossbauer spectroscopy and TEM microscopy which confirmed the presence of magnetite and akaganeite phases, with an average diameter of 20−43 nm. Nanoparticles by thermal decomposition method were investigated by XRD, UHR-FE-SEM and HRTEM and showed the formation of magnetite nanoparticles with an average diameter of 6.7 ± 1.4 nm. Subsequently, the nanoparticles were evaluated in a batch reactor using HCO from the Golden Lane of Mexico at 44.1 bar (initial H2 pressure) and 380 °C, for 1 h at 500 rpm. It was observed that, even under hydrogen limited conditions, there are better physicochemical properties in terms of viscosity, API gravity and heavy fractions decrease, for example, the residue conversion was about 20 % and the kinetic model was adjusted to a five lump model. The formation of the iron sulfide phase (FeS) was detected during the analysis of the spent catalyst.

In order to clarify the solvent extraction and separation behaviors of rare earths and impurity of Al during the extraction and enrichment of low-concentration leach solution of ion-adsorption rare earth ore, the extraction mechanism and separation behaviors of Nd3+ and Al3+ in the Nd2(SO4)3–Al2(SO4)3 mixed solution using P507 were studied in this work. The extraction of Nd3+ and Al3+ follows the cation exchange mechanism. With the increase of the equilibrium pH, βNd/Al in the extraction of the Nd2(SO4)3–Al2(SO4)3 mixed solution using P507 is always higher than that in the extraction of single Nd2(SO4)3 and Al2(SO4)3 solutions. It can be attributed to the fact that the extraction of Nd3+ using P507 is much faster than that of Al3+, and Al3+ is more prone to be hydrolyzed at lower pH. βNd/Al in the extraction of the Nd2(SO4)3–Al2(SO4)3 mixed solution decreases gradually with the increase of mixing time within the equilibrium pH range of 1.5–1.9. The extraction of Nd3+ using P507 is much faster than that of Al3+, but the stability of Al3+-loaded organic phase is better than that of Nd3+-loaded organic phase, thus Nd3+ in the Nd3+-loaded organic phase is gradually replaced by Al3+ in the aqueous phase with the increase of mixing time.

We present a theoretical study using Halgren-Lipscomb algorithm assisted by DFT + U to determine the catalytic mechanism for hydrogen production by steam reforming of methanol over CeO2 and Ni/CeO2 model catalytic surfaces. Our main goal is to describe the physical-chemical interaction between nickel with CeO2 matrix support and catalytic conversion mechanism in response to experimental evidence. The results from transition energy states in ( 11 1 ¯ ) and ( 1 1 ¯ 1 ¯ ) CeO2 surfaces, with and without nickel cluster, indicate that process is favored when metallic nickel is contained, however, exothermic energies in bare CeO2 supports prior suggestions ascribing the particular catalytic activity enhancement of Ni/CeO2 nanorod for methanol steam reforming due a synergistic effect of the CeO2 exposed planes of the nanorods and Ni clusters. Our aim is to provide key data for the improvement and enhancement, in terms of efficiency and viability, the current production of hydrogen by methanol steam reforming by Ni/CeO2 systems.

The major findings in this report are (i) development of nanocomposite photocatalyst working through Z-scheme charge transfer pathway across the heterojunction, (ii) utilization of direct sunlight as the photo-source, (iii) prospect of ligand-hole in photocatalysis through enhanced sub-band gap absorption. The photocatalysts, namely LaNiO3, g-C3N4 and LaNiO3/g-C3N4 nanocomposites were synthesized via facile route and were characterized for their structure, morphology, microstructure, texture, elemental mapping and surface oxidation states by using several physicochemical techniques. The photocatalytic performance of the nanocomposite was tested through the degradation of hazardous azo dye pollutants, namely reactive black 5 and methylene blue as well as the colorless antibiotic-pollutant tetracycline hydrochloride in aqueous solution in presence of natural sunlight with excellent recycling activity. The 10%LaNiO3/g-C3N4 nanocomposite sample shows best catalytic activity, degrading respectively 94%, 98.6% and 88.1% of reactive black 5, methylene blue and tetracycline hydrochloride in 60 min, 180 min and 120 min. The photocatalytic activity of the nanocomposite phase is several times superior to that of the pure phases. The improvements of photocatalytic activity of g-C3N4 in the nanocomposite have been rationalized through the construction of direct Z-scheme heterojunction and suppression of electron-hole pair recombination efficiency. The enhanced photo-absorption of the nanocomposite can possibly be related to sub-bandgap absorption, which is associated to the midgap state originated from ligand-hole formation or defects in the structure. The photodegradation process is mediated through the formation of super oxide radical (˙O2¯) and hole (h+) as the main responsible species.

As the oxygen redox ability shows great effects on the catalytic performances of ceria-zirconia based materials, many strategies have been utilized to improve the oxygen storage capacity. Here in this study, we report a simple and facile approach to prepare a SO42–-modified La, Y-doped ceria-zirconia material (SO/CZLY-f) with high oxygen storage capacity. Due to the additional redox process between SO42− and S2−, oxygen storage capacity of SO/CZLY-f (745.3 μmol O2/g) is about 1.6 times higher than that of La, Y-doped ceria-zirconia material without SO42– modification. Moreover, the catalytic activities and stability of the corresponding Pd-only three-way catalyst were measured. Compared to that of Pd@CZLY-f, the operation window of CO, full conversion temperature of HC and NO over Pd@SO/CZLY-f are obviously widened and lowered, respectively. After aging treatment at 1100 °C for 4 h, the superiority of aged Pd-loading composite is still maintained.

By intergranular addition of Pr-Cu-Ti alloy powders in the Nd-Fe-B sintered magnets with the normal B component, we propose an approach to the optimization of grain boundary and local Nd-Fe-B composition system. The coercivity is enhanced from 1.42 to 1.86 T, while further addition leads to a reduction in remanence and coercivity. The analyses of phase composition reveal that Ti mainly exists in the form of metallic Ti alloy, and part of Ti combines with B to form the TiB2 phase after the liquid phase sintering process. This process results in a consumption of B in the local Nd-Fe-B composition system and a change of the grain boundary component, which contributes to the formation process of the RE6(Fe,M)14 phase after the annealing process. Therefore, with the modification of grain boundary and composition system, the intergranular addition of Pr-Cu-Ti induces the generation of continuous thin grain boundary phases. It promotes the intergrain exchange decoupling, increasing the coercivity in the annealed magnet. While the excess addition results in the segregation of TiB2, as well as the precipitation of TiB2 into the Nd-Fe-B phase, which leads to structural defects. Thus, the further effort for the addition alloy with Ti to reduce the deterioration of the microstructure will lead to a further improvement in magnetic properties.

Non-toxic rare earth (RE) composite materials are promising and active in optoelectronic fields, such as pigment. In this work, Na ions doped γ-Ce2S3 pigments were synthesized by solid-phase vulcanization and followed by in-situ synthesis to prepare an outer layer of CePO4 film. The characterizations of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), solid state nuclear magnetic resonance (NMR) indicate that Na-doped γ-Ce2S3 and CePO4 uniformly and tightly coated core–shell structure was successfully synthesized. The thermogravimetric analysis (TG) and reflection spectrum (RS) reveal that the CePO4 coating significantly improves the colorant and thermal stability performance of γ-Ce2S3. The excellent color quality of γ-Ce2S3@CePO4 (L∗ = 45.16, a∗ = 55.94, b∗ = 44.53) is achieved and the red color (L∗ = 43.82, a∗ = 49.79, b∗ = 38.04) is still retained even if the sample is heated in air at 400 °C for 30 min.

A number of studies have focused on the effects of rare earth elements (REEs) on crop plants, while little attention has been paid on how tolerant plant species respond to increasing mixed REE concentrations. In this study, ramie (Boehmeria nivea L.) was exposed to a series of REE concentrations prepared with equimolar mixtures of 16 REEs (i.e. 0, 1.6, 8, 16, 80, 160, 400, 800 μmol/L) in order to explore REE accumulation and fractionation characteristics in ramie and the responses of this plant to mixed REEs. Results show that ramie root and shoot biomasses are unaffected under lower REE concentrations (1.6–80 μmol/L), while the growth of ramie and the uptake of nutrients especially Ca and Mn are largely inhibited under higher REE concentrations (160–800 μmol/L). The P and Mo concentrations in the roots increase with the increasing REE concentrations in the solution, suggestive of an involvement of P and Mo in dealing with the high concentrations of REEs in this plant. The preferential uptake of Ce and heavy REEs (HREEs) and the preferential transport of HREEs within the plant lead to a positive Ce anomaly and a HREE enrichment in ramie leaves. Our study suggests that ramie could be a good candidate for the phytoremediation of heavily REE-contaminated soils (e.g., REE mine tailings in southern China). Our results also shed light on points of taking into account phytoremediation management strategies of REE-contaminated soils (e.g., P and Mo fertilization).

Monazite ((Ce, La)PO4) is one of the major types of light rare earth minerals from which the light rare earth elements cerium (Ce) and lanthanum (La) are economically extracted. Flotation is extensively used to recover fine-grained monazite. Sodium oleate (NaOL) is considered as the collector with the strong collecting ability for monazite flotation. However, this study shows that its collecting ability is still limited. In this paper, a phosphonic acid, nonane-1,1-bisphosphonic acid (C9-BPA), was employed as the novel collector in place of NaOL. Flotation experiments show that even when the C9-BPA dosage is less than one-fifth of the NaOL dosage, the monazite recovery using C9-BPA as the collector is approximately 22 wt% higher than that using NaOL. The mechanism by which C9-BPA adsorbs on monazite was investigated using zeta potential, infrared (IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) measurements as well as first-principles calculations. Zeta potential measurements show a more significant decrease in the zeta potentials of monazite after the addition of C9-BPA compared to those after the addition of NaOL. For C9-BPA-treated monazite, the characteristic peaks of C9-BPA were observed in the IR and C 1s XPS spectrum, whereas for monazite treated by NaOL, no characteristic peak of NaOL was observed. Experimental results show that C9-BPA has a stronger affinity towards the monazite surface than NaOL as confirmed by the higher adsorption energy of CP-BPA on the monazite surface (‒204.22 kJ/mol) than NaOL (‒48.48 kJ/mol). This study demonstrates an extensive application value and prospect of C9-BPA in monazite flotation and helps design novel collectors with strong collecting ability for monazite flotation.

In this work, we investigated leaching of lanthanide and yttrium (REY) from a Central Appalachian coal and its ashes obtained at 550–950 °C with the main purpose of understanding the impact of ashing temperature on REY leachability in water, ammonium sulfate, and hydrochloric acid. It is found that the coal contains a negligible amount of water-soluble REY, less than 1% ion-exchangeable REY, and about 28% of HCl-soluble REY. Ashing leads to dramatic changes in REY leachability in both ammonium sulfate and hydrochloric acid solutions, which is believed to be related to transformation and redistribution of organically-associated REY in coal during the ashing process. Ashing temperature significantly affects REY leaching from coal ashes; higher ashing temperature results in lower REY leachability in both solutions. Clay minerals may play a significant role in changing the leachability of REY after ashing. In addition, the results also suggest that the organic matter in the coal is relatively enriched in heavy REY.

New energy vehicles and offshore wind power industries have a high demand for sintered Nd–Fe–B magnets with high intrinsic coercivity and high corrosion resistance. In this study, the magnetic properties, anticorrosion properties, and microstructure of Nd–Fe–B sintered magnets with the intergranular addition of low-melting-point eutectic Tb68Ni32 alloy powders were investigated. The aim is to determine if the addition of Tb68Ni32 could improve these properties. A low melting-point eutectic alloy Tb68Ni32 powders was prepared as a grain boundary additive and blended with the master alloy powders prior to sintering. The coercivity of the resultant magnets gradually increases from 1468 to 2151 kA/m by adding increasing amounts of Tb68Ni32. At the same time, the remanence first increases and then slightly decreases. After studying the microstructure and elemental composition of the Tb68Ni32 added magnets, it is found that the significant increase in coercivity and the negligible reduction in remanence is due to densification, improved grain orientation, a uniform and continuous boundary phase distribution, as well as the generation of a (Nd, Pr, Tb)2Fe14B “core–shell” structure surrounding the main-phase grain. Moreover, the corrosion resistance of the magnet is greatly improved owing to the enhancement of electrochemical stability, as well as the optimization of the distribution and morphology of the intergranular phase.

In this paper, we systematically investigated the microstructure evolution and coercivity mechanism of hydrogenation-disproportionation-desorption-recombination (HDDR) treated Nd-Fe-B strip cast alloys by transmission electron microscopy (TEM) and three-dimensional atom probe (3DAP) analyses. The rod-like NdH2+x phases with diameters of 10–20 nm are embedded into α-Fe matrix, which hereditarily leads to textured grains in HDDR alloy. The migration of NdH2+x from Nd-rich region to α-Fe matrix during hydrogen absorption process contributes to the uniform redistribution of Nd-rich phases after HDDR treatment. The HDDR alloy with single domain grain sizes of 200–300 nm exhibits relatively low coercivity of 1.01 T that arises from pinning magnetic domain motion. The weak c-axis orientation of HDDR alloy results in a lower reverse magnetic field (coercivity) to reduce remanence to 0. Moreover, the direct contact of Nd2Fe14B grains and the high concentration of ferromagnetic elements (Fe content ≈ 66.06 at%, Co content ≈ 0.91 at%) in Nd-rich grain boundary layer lead to strong magnetostatic coupling effect among Nd2Fe14B grains. The nano-sized α-Fe inside Nd2Fe14B matrix makes the magnetization reversal easily and decreases the coercivity of HDDR alloy.