Micro/nano metal–organic frameworks meet energy chemistry: A review of materials synthesis and applications

Micro/nano metal–organic frameworks(MOFs)have attracted significant attention in recent years due to their numerous unique properties,with many synthetic methods and strategies being reported for constructing MOFs with specific micro/nano structures.In addition,the design of micro/nano MOFs for energy storage and conversion applications and the study of the structure–activity relationship have also become research hotspots.Herein,a comprehensive overview of the recent progress on micro/nano MOFs is presented.We begin with a brief introduction to the various synthesis methods for controlling the morphology of micro/nano MOFs.Subsequently,the structure-dependent properties of micro/nano MOFs as electrode materials or catalysts in terms of batteries,supercapacitors,and catalysis are discussed.Finally,the remaining challenges and future perspectives in this field are presented.Overall,this review is expected to inspire the design of advanced micro/nano MOFs for efficient energy storage and conversion technologies.

Fabrication of Al_2O_3-NaCl Composite Heat Storage Materials by One-step Synthesis Method

Thermal energy storage is an attractive option for effectiveness since it gives flexibility and reduces energy consumption and costs. New composite materials for storage and transformation of heat of NaCl-Al2O3composite materials were synthesized by one-step synthesis method. The chemical composition, morphology, structure, and thermal properties were investigated by XRD, EDS, SEM, and DSC. The results show that NaCl can be absorbed by Al2O3particle from 800 to 900 ℃ for Al2O3particle surface is rich active structure. The results also indicate that the leakage of NaCl when the phase change can be prevented by Al2O3particles and the enthalpy of phase change of NaCl-Al2O3material is 362 J/g. The composites have an excellent heat storage capacity. Therefore, this study contributes to one new thought and method to prepare high temperature heat storage material and this material can be applied in future thermal engineering.

THE SYNTHESIS AND CHARACTERIZATION OF Ba-CROSSLINKED POLYMER ANTI-RADIATION MATERIALS

Crosslinked poly(methyl methacrylate) and polystyrene with barium dimethacrylate [Ba(MA)_2] as crosslinking agent have been synthesized. The relationship between X-ray absorbability and the content of Ba(MA)_2 in polymers was investigated. TGA and DSC results indicated that the crosslinked polymers containing barium dimethacrylate have a much better heat stability than pure PMMA or PS. The mechanical properties of the polymers containing barium are improved in comparison with the pure PMMA.

Laser-Heated Diamond-Anvil Cell (LHDAC) in Materials Science Research

Laser-heated diamond-anvil cell (LHDAC) is emerging as the most suitable, economical and versatile tool for the measurement of a large spectrum of physical properties of materials under extreme pressure and temperature conditions. In this review, the recent developments in the instrumentation, pressure and temperature measurement techniques, results of experimental investigations from the literature were discussed. Also, the future scope of the technique in various avenues of science was explored.

APPLICATION OF HYDROTHERMAL TECHNOLOGY IN MATERIAL SYNTHESIS - A SELECTIVE REVIEW

This paper is a brief and selective review on hydrothermal synthesis of advanced materials. Some general comments about the hydrothermal synthesis of materials are presented. In particular, the surface modification and hydrothermal synthesis of functional powders (e.g. the hydrothermal coating of aluminum borate whiskers with chromium oxide, hydrothermal synthesis of Ni-Zn ferrite and magnesium hydroxide ) are introduced and their importance are explained.

Effect of Surfactant/Silica and Hydrothermal Time on the Specific Surface Area of Mesoporous Materials from Coal-Measure Kaolin

Mesoporous materials with the highest surface area were synthesized by hydrothermal treatment from coal-measure kaolin using cetyltrimethylammonium bromide（CTAB）as template.The effect of several factors on surface area of products also had been discussed.The products were characterized by FT- IR,HRTEM and N 2 adsorption and desorption isotherm plot methods.There was typical structure as Si-O,Si- OH and Si-O-Si of mesoporous materials in the framework of synthesized materials;the pore size distributions of the products showed a sharp peak at 3.82 nm.The effect of hydrothermal treatment time and the amount of template on the specific surface area of mesoporous materials was important,when the Surf/Si=0.135,and hydrothermal time=12 h,and the surface area of the product reached up to 1 070 m2/g,which was higher than other products.

Solution combustion synthesis of Fe-Ni-Y_2O_3 nanocomposites for magnetic application

Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characteristics and phase transformation of the combusted powder and the Fe-Ni-Y2O3 nanocomposites were characterized by XRD, FESEM and TEM.Porous Fe-Ni-Y2O3 nanocomposites with crystallite size below 100 nm were obtained after reduction. The morphology, phases and magnetic property of Fe-Ni-Y2O3 nanocomposites reduced at different temperatures were investigated. The Fe-Ni-Y2O3 nanocomposite reduced at 900 °C has the maximum saturation magnetization and the minimum coercivity values of 167.41 A/(m2·kg)and 3.11 k A/m, respectively.

In situ synthesis of Fe-based alloy clad coatings containing TiB_2–TiN –(h-BN)

Fe-based alloy coatings containing TiB2–TiN –（h-BN） were synthesized in situ on Q235 steel substrates by a plasma cladding process using the powders of Fe901 alloy, Ti, and h-BN as raw materials. The effects of Ti/h-BN mass ratio on interfacial bonds between the coating and substrate along with the microstructures and microhardnesses of the coatings were investigated. The results show that the Ti/h-BN mass ratio is a vital factor in the formation of the coatings. Free h-BN can be introduced into the coatings by adding an excess amount of h-BN into the precursor. Decreases in the Ti/h-BN mass ratio improve the microstructural uniformity and compactness and enhance the interfacial bonds of the coatings. At a Ti/h-BN mass ratio of 10/20, the coating is free of cracks and micropores, and mainly consists of Fe-Cr, Fe3B, TiB2, TiN, Ti2N, TiB, FeN, FeB, Fe2B, and h-BN phases. Its average microhardness in the zone between 0.1–2.8 mm from the coating surface is about Hv0.2 551.5.

Experimental Investigation on Finishing Technology by Magnetostrictive Ultrasonic Vibration of Magnetic Liquid

Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoelectric transducers,the ultrasonic wave generated by the vibration of magnetic liquids can be detected,which shows that the magnetic liquids have the magnetostrictive effect and can generate the ultrasonic vibration under the alternative magnetic gradient field.Some nonmagnetic abrasives and rust-proofing agents can be mixed into the magnetic liquids,under the alternative magnetic field,the abrasives held by magnetic liquids grind the surface of the workpieces,and thus,the finishing for the surface with complex shape,mold cavity and inner wall of tiny tubes can be realized.

Preparation and characterization of GaN films grown on Ga-diffused Si (111) substrates

Hexagonal GaN films were prepared by nitriding Ga_2O_3 films with flowingammonia. Ga_2O_3 films were deposited on Ga-diffused Si (111) substrates by radio frequency (r.f.)magnetron sputtering. This paper have investigated the change of structural properties of GaN filmsnitrided in NH_3 atmosphere at the temperatures of 850, 900, and 950 deg C for 15 min and nitridedat the temperature of 900 deg C for 10, 15, and 20 min, respectively. X-ray diffraction (XRD),scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectronspectroscopy (XPS) were used to analyze the structure, surface morphology and composition ofsynthesized samples. The results reveal that the as-grown films are polycrystalline GaN withhexagonal wurtzite structure and GaN films with the highest crystal quality can be obtained whennitrided at 900 deg C for 15 min.

Microencapsulation of stearic acid with polymethylmethacrylate using iron(Ⅲ) chloride as photo-initiator for thermal energy storage

Aiming to identify the validity of fabricating microencapsulated phase change material(PCM) with polymethylmethacrylate(PMMA) by ultraviolet curing emulsion polymerization method using iron(III) chloride as photoinitiator,SA/PMMA microcapsules were prepared and various techniques were employed to determine the ignition mechanism,structural characteristics and thermal properties of the composite.The results shown that the microcapsules containing SA with maximum percentage of 52.20 wt% formed by radical mechanism and only physical interactions existed in the components both in the prepared process and subsequent use.The phase change temperatures and latent heats of the microencapsulated SA were measured as 55.3 °C and 102.1 J·g^(-1) for melting,and 48.8 °C and 102.8 J·g^(-1) for freezing,respectively.Thermal gravimetric analysis revealed that SA/PMMA has good thermal durability in working temperature range.The results of accelerated thermal cycling test are all shown that the SA/PMMA have excellent thermal reliability and chemical stability although they were subjected 1000 melting/freezing cycles.In summary,the comparable thermal storage ability and good thermal reliability facilitated SA/PMMA to be considered as a viable candidate for thermal energy storage.The successful fabrication of SA/PMMA capsules indicates that ferric chloride is a prominent candidate for synthesizing PMMA containing PCM composite.

Unraveling transition-metal-mediated stability of spinel oxide via in situ neutron scattering

The energy materials performance is intrinsically determined by structures from the average lattice structure to the atom arrangement, valence, and distribution of the containing transition metal(TM) elements. Understanding the mechanism of the structure transition and atom rearrangement via synthesis or processing is key to expediting the exploration of excellent energy materials. In this work, in situ neutron scattering is employed to reveal the real-time structure evolution, including the TM-O bonds, lattice,TM valence and the migration of the high-voltage spinel cathode LiNi_(0.5)Mn_(1.5)O_(4). The transition-metalmediated spinel destabilization under the annealing at the oxygen-deficient atmosphere is pinpointed.The formation of Mn^(3+) is correlated to the TM migration activation, TM disordered rearrangement in the spinel, and the transition to a layered-rocksalt phase. The further TM interdiffusion and Mn^(3+) reduction are also revealed with multi-stage thermodynamics and kinetics. The mechanisms of phase transition and atom migrations as functions of temperature, time and atmosphere present important guidance on the synthesis in various-valence element containing oxides.

Two Near-infrared Emissive Lanthanide-based Metal-organic Complexes Constructed from Efficient Energy Transfer Ligand

Utilizing two polycarboxylic acids as primary ligands and 1,10-phenanthrolion as an auxiliary ligand in the existence of lanthanide nitrates, two lanthanide-based complexes formulated as [Nd4（2,6-pydc OH）6（Phen）4（H2O）2]（H2O）2（1） and [Yb2（mBDC）3（Phen）2]n（2）（2,6-H2 pydc OH = 4-hydroxypyridine-2,6-dicarboxylic acid, m-H_2BDC = isophthalic acid, Phen = 1,10-phenanthroline） have been solvothermally synthesized. They have been fully characterized by satisfactory elemental analysis, FT-IR spectra, TGA and single-crystal X-ray diffraction. Single-crystal X-ray diffraction study reveals that 1 has a zero-dimensional structure and 2 exhibits a rare cds topological net structure. Compounds 1 and 2 exhibit strong characteristic emissions of Nd（Ⅲ） and Yb（Ⅲ） ions in the near-infrared（NIR） region.

Structure and Optical Property of a New 1D Iodoplumbate Hybrid Directed by in situ Synthesized Asymmetrical N-benzyl-1,4-diazabicyclo[2.2.2]octane

Simple solvothermal reaction of PbI2,1,4-diazabicyclo[2.2.2]octane and benzyl alcohol in the presence of HI acid creates a new organically templated iodoplumbate hybrid：[（N-Bz-DABCO）（PbI3）]n（1,N-Bz-DABCO＋ = N-benzyl-1,4-diazabicyclo[2.2.2]octane）.Compound 1 crystallizes in orthorhombic space group P212121 with a = 20.044（9）,b = 8.002（3）,c = 12.345（5） ？,V = 1980.1（14） A3,Z = 4,C（13）H（19）N2PbI3,Mr = 791.19,Dc = 2.654 g/cm^3,F（000） = 1408,μ（Mo Kα） = 13.189 mm–1,the final R = 0.0303 and w R = 0.0849 for 3777 observed reflections（I 〉 2σ（I））.Compound 1 contains one-dimensional anionic [PbI3]nn-chains that are enclosed into the cationic channel formed from the N-benzyl-1,4-diazabicyclo[2.2.2]octane.Noteworthy,compared with common symmetrical N,N？-dialkyl-DABCO^（2＋） cations,in-situ formed asymmetrical N-monoalkyl-DABCO~＋ cation is first used as structure directing agents/templating agents in the haloplumbate system,finally leading to the occurrence of noncentrosymmetric feature in compound 1.In addition,UV-Vis absorption spectrum analysis reveals that compound 1 is a potential semiconductor material with energy gap of 2.80 eV.

Materials for evaporation-driven hydrovoltaic technology

Water constitutes the largest energy carrier on earth,absorbing more than 70%of the solar energy received by the earth's surface,yet its low exploitation has been a constant concern.The hydrovoltaic effect is an emerging technology that generates electricity through the direct interaction between nanomaterials and water of various forms(raindrops,waves,flows,moisture,and natural evaporation).Especially,the evaporation-driven hydrovoltaic effect is a spontaneous and ubiquitous process that can directly convert thermal energy from the surrounding environment into electricity without the demand for additional mechanical work,which shows unique advantages compared with other hydrovoltaic effects.A variety of nanostructured materials have been steadily developed for evaporation-driven hydrovoltaic devices(EHDs)in recent years.However,there has been a lack of a clear specification on the selection and design of materials for improving device performance.Herein,we first analyze the mechanisms of EHDs followed by a summarization of the recent advances in materials,including carbon materials,biomass-based materials,metal oxides,composite materials,and others.We then discuss the strategies for improving the energy conversion efficiency and the output power in terms of structural design,surface modification,and interface treatment.Finally,we provide an outlook on the potential applications of electricity generation,sensors,and desalination technology,as well as the challenges and prospects for the development of this emerging technology in the future.

High throughput materials research and development for lithium ion batteries

Development of next generation batteries requires a breakthrough in materials.Traditional one-by-one method,which is suitable for synthesizing large number of sing-composition material,is timeconsuming and costly.High throughput and combinatorial experimentation,is an effective method to synthesize and characterize huge amount of materials over a broader compositional region in a short time,which enables to greatly speed up the discovery and optimization of materials with lower cost.In this work,high throughput and combinatorial materials synthesis technologies for lithium ion battery research are discussed,and our efforts on developing such instrumentations are introduced.

Facile Synthesis of Bimetallic Au@Pd Nanoparticles with Core-shell Structures on Graphene Nanosheets

In this paper, we report a simple one-step thermal reducing method for synthesis of bimetallic Au@Pd nanoparticles with core-shell structures on the graphene surface. This new type of Au@Pd-G composites is characterized by transmission electron microscopy, high resolution transmission electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. It is found that Au@Pd nanoparticles with an average diameter of 11 nm are well dispersed on the graphene surface, and the Au core quantity as well as the Pd shell thickness can be quantitatively controlled by loading different amounts of metallic precursors, and the involved core-shell structure formation mechanism is also discussed. The ternary Pt/Au@Pd-G composites can also be synthetized by the subsequent Pt doping. The catalytic performance of Au@Pd-G composites toward methanol electro-oxidation in acidic media is investigated. The results show that Au@Pd-G composites exhibit higher catalytic activity, better stability and stronger tolerance to CO poisoning than Pd-G and Au-G counterparts.

Development of In Situ MAS NMR and Its Applications in Material Synthesis and Heterogeneous Catalysis

High-resolution magic angle spinning(MAS)NMR can afford both qualitative and quantitative information of the solid,liquid and gas phase at atomic level,and such information obtained at in situ/operando conditions is of vital importance for understanding the crystallization process of material as well as the reaction mechanism of catalysis.To meet the requirement of experimental conditions for material synthesis and catalytic reactions,in situ MAS NMR techniques have been continuously developed for using at higher temperatures and pressures with high sensitivity.Herein,we will briefly outline the development of this technology and discuss its detailed applications in understanding material synthesis and heterogeneous catalysis.

Recent progress in synthesis of two-dimensional hexagonal boron nitride

Two-dimensional（2D） materials have recently received a great deal of attention due to their unique structures and fascinating properties,as well as their potential applications.2D hexagonal boron nitride（2D hBN）,an insulator with excellent thermal stability,chemical inertness,and unique electronic and optical properties,and a band gap of 5.97 e V,is considered to be an ideal candidate for integration with other 2D materials.Nevertheless,the controllable growth of high-quality 2D h-BN is still a great challenge.A comprehensive overview of the progress that has been made in the synthesis of 2D h-BN is presented,highlighting the advantages and disadvantages of various synthesis approaches.In addition,the electronic,optical,thermal,and mechanical properties,heterostructures,and related applications of 2D h-BN are discussed.

Synthesis and Properties of Monodisperse Superparamagnetic Mg_(0.8)Mn_(0.2)Fe_2O_4 Nanoparticles Using Polyol Reflux Method

Superparamagnetic monodisperse Mg0.8Mn0.2Fe2O4 nanoparticles have been successfully synthesized in liquid polyol at elevated temperature of 200 °C. Diethylene glycol（DEG） used here plays dual role in synthesis as it acts as reducing agent and alternatively coats the surface of nanoparticles while synthesis and thereby maintaining uniform size and dispersibility. Powder X-ray diffraction（XRD） and magnetic measurements showed that the sample is cubic spinel and superparamagnetic at room temperature. Raman spectra confirmed the formation of the Mg0.8Mn0.2Fe2O4 nanoparticles.The nanoparticles exhibit very good stability in water due to in situ coating with DEG molecules.