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Abstract Na-ion batteries (NIBs) have been suggested as one of the most promising technologies for low-cost rechargeable batteries due to the earth-abundance resource of sodium. However, the delivery of high-performance cathode is still facing a great challenge especially for the development of Na-ion full batteries towards practical application. Herein, we present a layered biphasic cathode with P2 and P3 integrated structures, which is clearly elucidated by X-ray diffraction refinement, high resolution transmission electron microscopy and selected area electron diffraction. Combining the respective characteristics of P2 and P3 phases and highly reversible P2/P3–P2/OP4 structural evolution, the layered composite delivers a high reversible capacity of 119 mA h g−1 with a superior initial Coulombic efficiency of 94.8%, a high operating voltage of 3.53 V vs Na+/Na based on Ni2+/Ni4+ redox couple, and an outstanding rate performance (capacity retention of 85.5% at 5C compared with 0.2C). Furthermore, the assembled Na-ion full battery of P2/P3-Na 0.7 Li 0.06 Mg 0.06 Ni 0.22 Mn 0.67 O 2 //hard carbon exhibits a high average voltage of 3.36 V with a calculated energy density up to 218 W h kg−1. Our contribution paves a smart way for designing sodium-ion full batteries with both high energy density and good cycling stability toward practical application. Graphical abstract P2/P3-Na 0.7 Li 0.06 Mg 0.06 Ni 0.22 Mn 0.67 O 2 composite cathode integrating the structural advantages of P2 and P3 phases is synthesized through the temperature-induced P3–P2 phase transition. The Na-ion full cell with P2/P3-NLMNM//hard carbon exhibits a high working voltage of 3.36 V (vs Na+/Na) with energy density up to 218 W h kg−1. fx1 Highlights • Novel layered P2/P3 biphasic structure is prepared by monitoring phase evolution. • The integrated cathode exhibits an enhanced capacity retention and rate performance via a reversible P2/P3–OP4/P3 phase transition. • Charge compensation mechanism is revealed by ex situ XANES and EXAFS. • Na-ion full battery delivers a high average voltage (3.36 V) and energy density (218 W h kg–1). [ABSTRACT FROM AUTHOR]

Abstract: Acrylonitrile–butadiene–styrene (ABS) resin is widely used as an important engineering thermoplastic polymer in various industrial applications, but suffers from easily burning and generating a large amount of smoke and toxic gases. Here we report a utilization of hydrotalcite-like MgA1- and ZnMgA1-layered double hydroxides (MgA1- and ZnMgA1-LDHs) as an inorganic flame retardant to ABS resin. The LDHs were prepared by a scalable method involving separate nucleation and aging steps (SNAS). The performances of the LDHs/ABS composites were evaluated by measuring limiting oxygen index (LOI), smoke density (Dm), heat release rate (HRR), and average mass loss rate (av-MLR). The results obtained show that both LDH/ABS composites exhibit higher LOI and lower Dm values, lower values of pk-HRR and av-MLR, and a prolonged combustion time, in comparison with the pristine ABS. Comparison between MgAl- and ZnMgAl-LDH-containing composites shows that the introduction of Zn2+ is able to facilitate flame retardance, smoke suppression efficiency, and tensile strength elongation rate of the ZnMgAl-LDH/ABS composite. Our results show that LDHs may be used as a type of promising inorganic flame retardant to enhance smoke suppression and flame retardant for ABS resin. [Copyright &y& Elsevier]

Abstract: CoFeIIFeIII-layered double hydroxide (LDH) hollow spheres with two distinctly different hierarchical morphologies—flower-like and raspberry-like, involving edge-on and face-on oriented LDH platelets as building blocks, respectively—can be fabricated by tuning the rate of addition of NaOH solution in a coprecipitation process with sulfonated polystyrene spheres as a template. Ex situ pH-dependent microscopic observations of the formation of the flower-like LDH shells shows the details of non-classic nucleation and growth underlying the edge-on orientation. After calcination, the resulting CoFe2O4 materials retain the hierarchical morphology of the corresponding LDH precursor. The hollow CoFe2O4 spheres with raspberry-like morphology exhibit magnetic properties comparable to a reference material obtained by calcination of a conventional LDH powder precursor. Similar materials with tunable magnetic properties can be prepared by virtue of the flexibility in LDH layer composition. The CoFeIIFeIII-LDH spheres with a raspberry-like morphology may be also be prepared by using a scalable procedure involving separate ultra-rapid nucleation and aging steps in a modified colloid mill reactor. The results reported here may open up the possibility of producing shell structures with controllable morphologies and properties on a large scale. [Copyright &y& Elsevier]

Abstract: A hybrid film containing a substituted azobenzene, 7-[(trifluoromethoxyphenylazo)phenoxy]pentanoate anion , intercalated in a layered double hydroxide (LDH) film immobilized on a porous anodic alumina/aluminum (PAO/Al) substrate has been prepared by an anion-exchange reaction of a ZnAl––LDH/PAO/Al precursor film with the sodium salt of anions under mild conditions. The hybrid LDH film was characterized by scanning electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. TG–DTA, UV–visible spectroscopy and CIE 1976 color difference tests indicated that the intercalated ZnAl––LDH showed enhanced thermo-stability and photo-stability compared to the pristine salt. Irradiation with UV light led to a switch in wettability of the film from superhydrophobic to hydrophilic and this process could be reversed by subsequent irradiation with visible light. [Copyright &y& Elsevier]

• Hollow ultra-microporous carbon spheres are prepared as anode materials for SIBs. • 96.62 % capacity retention over 500 cycles at 2 A g–1 and rate performance (233.64 mAh g–1 at 10 A g–1) are achieved. • The abundant ultra-micropores predominantly contribute to the enhancement. Hollow porous carbon spheres are considered as promising anode nanomaterials for sodium-ion batteries (SIBs), but suffer from the problems of poor rate and cycling performances. Typical improvement strategies by creating micropores or mesopores are used to boost cycling and rata performances. Herein, hollow porous carbon spheres (HPCS) with ultra-micropores are prepared as anode nanomaterials for SIBs. The optimized HPCS-2 delivers a decent capacity of 272.3 mAh g−1 at 0.1 A g−1, a capacity retention rate of 96.62% over 500 cycles at 2 A g–1, and, in particular, a remarkable rate performance of 233.64 mAh g–1 at 10 A g–1. The great enhancement is elucidated predominantly by the abundant ultra-micropores that provide rapid ion-transport pathways and accelerated sodium-ion diffusion coefficient. The results promise rational design and preparation of high-rate carbon anode nanomaterials for sodium storage. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: In order to fully exploit the green characteristics of solid base catalysts they should be fabricated into macrostructured rather than powder form. Magnesia-rich magnesium aluminate spinel framework catalysts with tunable basicity have been prepared by using macrospheres (0.5–1.0mm in diameter) as a hard template. The process involves in situ growth of magnesium–aluminum layered double hydroxides (MgAl-LDHs) in the channels of the macrospheres by the urea hydrolysis method, followed by calcination, tuning of the basicity through etching of excess aluminum with aqueous alkali and a final calcination step. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), elemental analysis and low temperature N2 adsorption–desorption studies demonstrate that the composite materials are composed of nanosized rod-like particles aggregated into a spherical framework. Catalytic reactivity was investigated by using methanolysis of soybean oil as probe reaction. The composite shows a higher biodiesel yield compared to an material with the same loading of magnesium prepared by a conventional impregnation method. The enhanced catalytic activity of the former material can be ascribed to its higher basicity, specific surface area, pore volume and pore size. [Copyright &y& Elsevier]

The development of highly efficient and low-cost electrocatalysts for the oxygen evolution reaction (OER) is of great importance in advancing the practical applications of green and sustainable hydrogen energy. Doping with either cations or non-metallic anions is a typical strategy used to improve the electrocatalytic activity for OER catalysts. In this study, an anion doped bimetallic selenide Co 0.75 Fe 0.25 (S 0.2 Se 0.8) 2 solid solution is prepared via the simultaneous sulfuration and selenylation of a scalably produced CoFe-layered double hydroxide (CoFe-LDH) precursor, using commercially available sulfur and selenium powders as S and Se sources, respectively. Electrocatalytic test shows that the anion doped bimetallic selenide Co 0.75 Fe 0.25 (S 0.2 Se 0.8) 2 electrode requires an overpotential of 293 mV and a low Tafel slope of 77 mV dec−1 at a current density of 10 mA cm−2 in an alkaline media, and it exhibits the significantly enhanced electrocatalytic performance for the OER compared with its counterparts of Co 0.75 Fe 0.25 S 2 and Co 0.75 Fe 0.25 Se 2. The enhanced electrocatalytic performance is supported experimentally by the results of charge-transfer resistance and electrochemically active surface area. Our LDH precursor-based protocol can provide a strategy to prepare non-metallic anion doped bimetallic selenides as efficient electrocatalysts for water splitting. [ABSTRACT FROM AUTHOR]

Co nanoparticle-encapsulated N-doped carbon nanotubes (Co@N-CNTs) are prepared as a Pt-free electrocatalyst for oxygen reduction reaction (ORR) via direct pyrolysis of a CoAl-layered double hydroxide (CoAl-LDH)/melamine mixture. The approach could bundle the following distinct features: (i) commercially available melamine as both carbon and nitrogen bi-functional sources; (ii) scalably prepared CoAl-LDH precursor chosen to play a triple role in catalyzing the formation of N-CNTs and serving the electroactive Co nanoparticles, as well as in facilitating the growth of long N-CNTs owing to the confinement effect of the non-active Al 2 O 3 matrix formed; (iii) an alternative to prepare one-dimensional length-and-performance-tunable N-CNTs, which are obtained typically by using catalytic chemical vapor deposition (CCVD) of two gaseous carbon and nitrogen resources on the surface of an LDH layer. The long Co@N-CNTs exhibits the highly enhanced electrocatalytic activity and stability for ORR (onset potential at 929 mV, half-wave potential at 849 mV vs. RHE, and limited current density at 6.0 mA cm −2 ). The CoAl-LDH precursor-based approach may open up a simple and feasible alternative to design and produce low-cost electrocatalysts for fuel cells. [ABSTRACT FROM AUTHOR]

We describe a preparation of sulfur-doped mesoporous amorphous carbon (SMAC) from a commercially available alkyl surfactant sulfonate anion-intercalated NiAl-layered double hydroxide precursor via thermal decomposition and subsequent acid leaching. The resultant amorphous carbon is endowed with the integrated advantage of featuring high reversible capacity and long cycling stability: intrinsic doping of sulfur, large specific area, and broad mesopore size distribution. Electrochemical evaluation shows that the SMAC electrode exhibits highly enhanced electrochemical performances, compared with the electrode of non-doped mesoporous and amorphous carbon prepared by using a different surfactant (sodium laurate). A high reversible capacity of 958 mA h g −1 is achieved for the SMAC electrode after 110 cycles at 200 mA g −1 , and especially a superlong cycle life with a reversible capacity of 579 mA h g −1 after 970 cycles at 500 mA g −1 . Moreover, the SMAC electrode can facilitate the reversible insertion/extraction of Na ion, owing to the proper specific area and mesopore size distribution, as well as the improved electronic conductivity resulted from doping of sulfur. [ABSTRACT FROM AUTHOR]

Layered transition-metal oxides have been potential as high-performance cathode materials for sodium-ion batteries (SIBs), however, suffer from the undesirable side reactions between cathode/electrolyte interface during cycling. One improvement strategy by surface coatings is typically used, but at the compromise of lowering ion transport kinetics and poor rate capability. Herein, we report a surface optimized high-rate P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode material for SIBs via a highly conductive Al-doped ZnO (AZO). By tuning the calcination temperatures, the optimized cathode material coated with 1 wt% AZO at 500 °C exhibits decent cycling and rate performances (66.2 mAh g−1 with a capacity retention of 82.6% at 5C after 500 cycles). Electrochemical kinetics analysis demonstrates that the NM@AZO-500 exhibits a high Na+ diffusion coefficient and a low charge-transfer resistance, and in-situ X-ray diffraction (XRD) and ex-situ X-ray photoelectron spectroscopy (XPS) reveal that the AZO coating effectively relieves the lattice stress during cycles and inhibits undesirable side reaction; all of which give rise to the observed enhancement. The result promises an effective surface optimized route for high-performance cathode materials for SIBs by coating highly conductive oxide. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] Carbon-supported Ni@NiO/Al2O3 nanocomposite was prepared from LDH/C precursor. [•] Enhanced specific capacity and cycling stability are obtained. [•] EIS and TEM results provide convincing information underlying the enhancements. [ABSTRACT FROM AUTHOR]

Abstract: Porous semiconductor photocatalysts which are active under illumination by visible light have attracted extensive attention recently due to their remarkable well-designed physical and chemical properties. Here, novel mesoporous Zn x Cd1−x S nanoparticles have been successfully fabricated by a two-steps strategy: Al-Zn x Cd1−x S nanoparticles which are homogeneously distributed within the confinement of an amorphous alumina matrix was first synthesized by in situ gas–solid reaction of a single precursor—a Zn2+,Cd2+,Al3+-containing layered double hydroxides (ZnCdAl-LDHs)—with gaseous H2S; subsequently, selective leaching of amorphous alumina by sodium hydroxide solution from the as-prepared Al-Zn x Cd1−x S nanoparticles was carried out, with the aim of achieving the introduction of mesopority in the chalcogenide semiconductor. The resulting mesoporous Zn x Cd1−x S nanoparticles can retain the uniform distributed structure with a network-like manner after the selective leaching of amorphous alumina. The absorption edge of the mesoporous Zn x Cd1−x S exhibit a monotonic blue shift within the visible light region as the amount of residual alumina decreased. The photocatalytic activities of the mesoporous Zn x Cd1−x S samples for the photodegradation of methylene blue (MB) dye molecules increase with the decline of alumina. And, the mesoporous Zn x Cd1−x S exhibits an enhanced photocatalytic performance compared to the pure CdS sample obtained from the same procedure without Zn2+, the unleached Al-Zn x Cd1−x S sample and the sample obtained by a coprecipitation method with the same composition. The homogeneous structure of the mesoporous Zn x Cd1−x S and the abundant surface hydroxyl groups are proposed to be beneficial to the generation of hydroxyl radicals, identified by electron spin resonance (ESR) spectra, leading to the higher photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Supported TiO2 nanoparticles have been successfully fabricated by selective reconstruction of a Cu2+, Mg2+, Al3+, Ti4+-containing layered double hydroxide (CuMgAlTi-LDH) precursor, synthesized by coprecipitation, through calcination and rehydration process. A systematic investigation of the structural characterization and the photodegradation tests of methylene blue (MB) dye molecules from solution under both UV and visible light irradiation for the resulting TiO2/CuMgAl-RLDH sample were carried out. Anatase-type TiO2 nanoparticles are found to be homogeneously distributed on the surface of the selectively reconstructed CuMgAl-RLDH support. And the direct evidence for the surface TiO2/LDH heterojunction formed on CuMgAl-RLDH is presented. For MB photodegradation under UV light or visible light illumination, TiO2/CuMgAl-RLDH sample has superior photocatalytic properties to the rehydrated single phase R-TiO2, the physical mixture of R-TiO2 and CuMgAl-RLDH, the composite CuTi/MgAl-RLDH synthesized by the rehydration of mixture of MgAl-MMO and CuTi-MMO, and the TiO2/MgAl-RLDH prepared under the same procedure as TiO2/CuMgAl-RLDH without containing Cu ions. The skeleton Cu2+ ions dispersed in the mainlayer of CuMgAl-RLDH support can enable the photocatalytic activity for MB photodegradation. The TiO2/LDH heterojunction nanostructure is proposed to contribute the efficient spatial separation between the photogenerated electrons and holes, which can concomitantly improve the photocatalytic activity. Our method provides a novel approach to fabricate new modes of load-type doped semiconductor photocatalysts which are both active under illumination by UV and visible light. [Copyright &y& Elsevier]

Abstract: Thiosulfate (S2O3 2−) is the main impurity in ammonium thiocyanate (NH4SCN) extracted from the effluent from industries such as electroplating or mining. It significantly lowers the quality of NH4SCN. Here we report a method for selective removal of S2O3 2− from aqueous solutions containing thiocyanate (SCN−) using the material produced by calcination of MgAl–CO3 hydrotalcites also known as layered double hydroxides (LDHs). The calcined materials, which we denote CLDHs, are well known scavengers for anionic contaminants. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) showed that CLDH exhibits selectivity in adsorption between S2O3 2− and SCN− anions, with preferential adsorption of S2O3 2− anions resulting in S2O3 2−-intercalated MgAl–LDHs. Selective removal of S2O3 2− from an aqueous mixed solution lowered the ratio of S2O3 2−:SCN− from 1:1 to approximately 1:7, which meets the requirements for production of high quality NH4SCN after recrystallization, or for direct reuse in the industrial process which produced the original effluent. At the same time, the by-product, S2O3 2−-intercalated MgAl–LDH showed satisfactory S2O3 2−-release behavior in a simulated solution, showing that is a potential slow-release sulfur fertilizer. Furthermore, its alkaline nature allows it to act as an effective acid soil conditioner. In this way, waste effluent posing an environmental hazard can be converted into two valuable products by a simple and economical process. [Copyright &y& Elsevier]

Abstract: Zn x Cd1−x S nanoparticles have been successfully synthesized by reaction of a single precursor – a Zn,Cd,Al-containing layered double hydroxide (ZnCdAl–LDH) – with H2S. The Zn x Cd1−x S nanoparticles are homogeneously distributed within the confinement of an amorphous alumina matrix, in marked contrast to the aggregation that occurs with Zn x Cd1−x S prepared by conventional coprecipitation. The photoactivities of the Zn x Cd1−x S nanoparticles for methylene blue (MB) photodegradation increased with decreasing Zn mole fraction x, and the best performance was achieved with a Zn mole fraction of 0.20. The Zn x Cd1−x S materials exhibited significantly better photocatalytic performance than Zn x Cd1−x S with the same composition obtained either by a coprecipitation method or by sulfuration of a physical mixture of Zn,Al–LDH and Cd,Al–LDH precursors. This suggests that the ordered arrangement on an atomic level of the metal cations within the LDH layers leads to a homogeneous array structure of the Zn x Cd1−x S solid solution, which suppresses the recombination of photoexcited electrons and holes, leading to improved photocatalytic activity. Our method provides a way to fabricate new types of chalcogenide semiconductor photocatalysts which are active under illumination by visible light. [ABSTRACT FROM AUTHOR]

Abstract: The wetting properties of two types of superhydrophobic layered double hydroxide (LDH) films modified by treatment with laurate (La) anions, film and ZnAl–La–LDH film, have been investigated using the sessile drop and Wilhelmy plate methods. The spreading kinetics of water droplets on ZnAl–La–LDH film surfaces was fitted by a power equation, and an effective lubrication coefficient was calculated. Unlike one-cycle measurements reported in a number of earlier studies, cycling contact angle measurements using the Wilhelmy plate method provide more information about the mechanism of contact angle hysteresis. Both the advancing contact angles () and the receding contact angles of film—in which the La anions are adsorbed on the surface of the LDH—obtained in different cycles were found to be independent of cycle number. In contrast, for the ZnAl–La–LDH film—in which the La anions are intercalated into the interlayer galleries of the LDH—the advancing contact angles () and the receding contact angles obtained in different cycles were found to vary. It was found that both and decreased with increasing number of cycles. The different contact angle hysteresis behaviors were qualitatively and quantitatively investigated by means of dynamic contact angle analysis. The results suggest that contact angle hysteresis of and ZnAl–La–LDH films can be ascribed to dynamic hysteresis and intrinsic hysteresis, respectively. [Copyright &y& Elsevier]

Abstract: Films of layered double hydroxides (M/Al-LDHs) with M=Ni, Zn have been fabricated on a porous anodic alumina/aluminum (PAO/Al) substrate via an in situ crystallization technique. The Ni/Al-LDH film has an orientation in which the ab-faces of the platelets are all perpendicular to the substrate whilst the LDH crystallites in the Zn/Al-LDH film are randomly orientated. Furthermore, the interlayer galleries of Ni/Al-LDH contain anions whereas NO3 − anions were found in the interlayer galleries of Zn/Al-LDH. These differences between the Ni/Al-LDH and Zn/Al-LDH films are, at first sight, surprising because the films were fabricated under identical experimental conditions. Two different mechanisms, homogeneous nucleation and the heterogeneous nucleation, have been proposed in order to account for the different growth processes of the Ni/Al-LDH and Zn/Al-LDH films, respectively. The two distinct growth mechanisms can satisfactorily account for the different crystallite orientations and types of interlayer ion in the M/Al-LDH (M=Ni, Zn) films. [Copyright &y& Elsevier]

Abstract: Mg/Al layered double hydroxide (LDH) films were fabricated in situ with anodic aluminum oxide (AAO)/aluminum as both the substrate and the sole aluminum source by means of urea hydrolysis. The structure and morphology of the LDH films were investigated by X-ray diffraction (XRD), attenuated total reflectance-Fourier transform infrared (ATR-FT-IR) and scanning electron microscopy (SEM), which show that hexagonal plate-shaped LDH crystallites grow perpendicularly on the substrate via a strong chemical interaction. After being activated by a calcination/rehydration procedure, the rehydrated LDH (RLDH) platelets remain firmly immobilized on the AAO/aluminum substrate and retain the hexagonal platelet morphology of the LDH precursor. The catalytic activity of the resulting material was tested by using aldol condensation of acetone as a probe reaction, showing that the RLDH/AAO is superior in catalytic performance to the powdered RLDH analogue. The kinetic feature of this catalytic reaction was also analyzed, which suggests that it obeys the kinetic model, a one-dimensional diffusion-controlled mechanism. [Copyright &y& Elsevier]

The development of high-efficiency anode nanomaterials (such as MoS 2) is critical to advancing sodium-ion batteries (SIBs) towards the practical application. Herein, MoS 2 nanoplatelets well-confined within CoS 2 nanobundles (MoS 2 /CoS 2) are prepared as anode nanomaterials for SIBs. The MoS 2 /CoS 2 composite is derived by the sulfidation of a guest/host precursor of PMo 12 O 40 3− anion-intercalated Co(OH) 2 via an interlayer nanoconfinement effect. Electrochemical testing demonstrates that the carbon-free MoS 2 /CoS 2 composite exhibits a high capacity of 396.6 mA h g−1 after 80 cycles at 0.1 A g−1, and retains a decent reversible capacity of 203.8 mA h g−1 after 300 cycles at 0.5 A g−1. The result shows that our gest/host precursor-based synthesis strategy may open up an effective approach to prepare well-dispersed nanostructural composites for SIBs. Image 1 • MoS 2 nanoplatelets well-confined within CoS 2 bundles are prepared as SIB anodes. • The composite is derived by sulfurizing PMo 12 O 40 3−/Co(OH) 2 via a nanoconfinement. • A decent capacity of 396.6 mA h g−1 is delivered at 0.1 A g−1 after 80 cycles. [ABSTRACT FROM AUTHOR]