ZIF-8-based micro-arc oxidation composite coatings enhanced the corrosion resistance and superhydrophobicity of a Mg alloy

Mg alloys are considered the most promising engineering materials because of their unique properties.However,the uncontrolled corrosion rate of these alloys limits their applications.Therefore,in this study,a micro-arc oxidation layer was used as a transition layer to“directly”grow a zinc-based metal-organic framework(MOF)composite coating on the surface of a Mg alloy(AZ91D).Herein,the two zeolitic imidazolate framework(ZIF-8)coatings with different morphologies were separately prepared by homologous metal oxide induction and a one-step in-situ growth method.The superhydrophobic composite coating showed strong hydrophobicity and self-cleaning properties,which could prevent the penetration of water and corrosive ions(Cl^(−))into the surface of AZ91D.Electrochemical tests demonstrated that the super-hydrophobic composite coatings greatly enhanced the corrosion resistance of AZ91D,and the corrosion current density decreased from 10^(−5)to 10^(−9)A/cm^(2).These results indicate that the ZIF-8 coatings are beneficial for improving the hydrophobicity and enhancing the corrosion resistance of Mg alloys.Therefore,MOF composite coatings provide a new strategy that can be used to prepare multifunctional anticorrosion coatings on metal substrates.

Corrosion resistance and anti-soiling performance of micro-arc oxidation/graphene oxide/stearic acid superhydrophobic composite coating on magnesium alloys

Magnesium(Mg)alloys,the lightest metal construction material used in industry,play a vital role in future development.However,the poor corrosion resistance of Mg alloys in corrosion environments largely limits their potential wide applications.Therefore,a micro-arc oxidation/graphene oxide/stearic acid(MAO/GO/SA)superhydrophobic composite coating with superior corrosion resistance was fabricated on a Mg alloy AZ91D through micro-arc oxidation(MAO)technology,electrodeposition technique,and self-assembly technology.The composition and microstructure of the coating were characterized by scanning electron microscopy,X-ray diffraction,energy dispersive spectroscopy,and Raman spectroscopy.The effective protection of the MAO/GO/SA composite coating applied to a substrate was evaluated using potentiodynamic polarization,electrochemical impedance spectroscopy tests,and salt spray tests.The results showed that the MAO/GO/SA composite coating with a petal spherical structure had the best superhydrophobicity,and it attained a contact angle of 159.53°±2°.The MAO/GO/SA composite coating exhibited high resistance to corrosion,according to electrochemical and salt spray tests.

Preparation and property of self-sealed plasma electrolytic oxide coating on magnesium alloy

Plasma electrochemical oxidation (PEO) is a surface modification technology to form ceramic coatings on magnesium alloys However,its application is limited due to its defects.This work reports a novel preparation of in-situ sealing of PEO coatings by four-layer voltage and sol addition.The morphology and structure were characterized by scanning electron microscopy (SEM),energy dispersive X-ray spectroscopy (EDS),and X-ray diffractometer (XRD).Image-Pro Plus 6.0 was used to determine the porosity of the coating,which was decreased from 8.53%to 0.51%.Simultaneously,the coating thickness was increased by a factor of four.The anti-corrosion performance of each sample was evaluated using electrochemical tests,and the findings revealed that the corrosion current density of coatings (i_(corr)) of the samples were lowered from 9.152×10^(-2) to 6.152×10^(-4) mA·cm^(-2),and the total resistance (R_(T)) of the samples were enhanced from 2.19×10^(4) to 2.33×10^(5)Ω·cm^(2).The salt spray test used to simulate the actual environment showed that corrosion points appeared on the surface of the coating only at the 336 h.In addition,the mechanism of PEO self-sealing behavior was described in this article.

Adsorption of CO_(2) on MgAl layered double hydroxides: Effect of intercalated anion and alkaline etching time

The adsorption of CO_(2) on MgAl layered double hydroxides(MgAl-LDHs) based adsorbents has been an effective way to capture CO_(2),however the adsorption capacity was hampered due to the pore structure and the dispersibility of adsorption active sites.To address the problem,we investigate the effect of intercalated anion and alkaline etching time on the structure,morphology and CO_(2) uptake performances of MgAl-LDHs.MgAl-LDHs are synthesized by the onepot hydrothermal method,followed by alkaline etching of NaOH,and characterized by x-ray diffraction,N_(2) adsorption,scanning electron microscopy and Fourier transform infrared spectroscopy.The CO_(2) adsorption tests of the samples are performed on a thermogravimetric analyzer,and the adsorption data are fitted by the first-order,pseudo-second-order and Elovich models,respectively.The results demonstrate that among the three intercalated samples,MgAl(Cl) using chloride salts as precursors possesses the highest adsorption capacity of CO_(2),owing to high crystallinity and porous structure,while MgAl(Ac) employing acetate salts as precursors displays the lowest CO_(2) uptake because of poor crystallinity,disorderly stacked structure and unsatisfactory pore structure.With regard to alkaline etching,the surface of the treated MgAl(Cl) is partly corroded,thus the specific surface area and pore volume increase,which is conducive to the exposure of adsorption active sites.Correspondingly,the adsorption performance of the alkaline-etched adsorbents is significantly improved,and MgAl(Cl)-6 has the highest CO_(2) uptake.With the alkaline etching time further increasing,the CO_(2) adsorption capacity of MgAl(Cl)-9 sharply decreases,mainly due to the collapse of pore structure and the fragmentized sheet-structure.Hence,the CO_(2) adsorption performance is greatly influenced by alkaline etching time,and appropriate alkaline etching time can facilitate the contact between CO_(2) molecules and the adsorbent.

Synthesis,Crystal Structure,Thermal Stability,Luminescence and Magnetic Property of a New Mn^Ⅱ Coordination Polymer

One new coordination polymer, [Mn(Hbtc)(bpy)(HO)]1, was synthesized by the reaction of manganese(Ⅱ) salt under pH-controlled hydrothermal conditions with unsymmetrical polycarboxylic acid of 1,2,4-benzenetricarboxylic acid(Hbtc) and 2,2?-bipyridine(bpy). The structure of complex 1 was characterized by single-crystal X-ray diffraction, IR spectra, powder X-ray analysis, thermal gravimetric analysis(TGA), UV-Vis spectrometry, photoluminescence and magnetic susceptibility. Complex 1 is a one-dimensional(1D) polymeric single-chain structure. Photoluminescence property is quite similar to the bpy ligand. Magnetic susceptibility measurement indicates that 1 shows a weak ferromagnetic coupling between the Mn~Ⅱ ions.

Synthesis, Structural Characterization and Magnetocaloric Effect of a Butterfly [CoⅡ2GdⅢ2] Cluster

2-(2,3-Dihydroxpropyliminomethyl)6-methoxyphenol(H3L), trimethylacetic acid(Hpiv), Gd(NO3)3·6 H2O and Co(NO3)2·6 H2O were reacted in Me OH to obtain a heterometallic tetranuclear cluster [Gd2Co2(L)2(μ3-OH)2(piv)6]·2 Hpiv·2 CH3OH(1). X-ray crystallographic analysis reveals that compound 1 was found to be a butterfly heterometallic tetranuclear cluster. The crystal(C64H108Co2Gd2N2O28, Mr = 1785.88) belongs to the triclinic crystal system, space group P1 with a =11.9798(6), b = 12.0877(5), c = 15.0367(7) A, α = 67.320(4)°, β = 81.583(4)°, γ = 75.201(4)°, V =1939.62(18) A3, Z = 1, T = 293.15 K, R = 0.048 and w R = 0.144 for 16299 observed reflections with I > 2σ(I). In magnetization study, heterometallic 1 exhibits magnetocaloric effect(MCE) of 14.75 J·kg-1·K-1 at 2 K for ΔH = 5 T, while it does not show non-linear response of the ac-susceptibilities.

ZnO@ZIF-8 core-shell structure nanorods superhydrophobic coating on magnesium alloy with corrosion resistance and self-cleaning

A longstanding quest in material science has been the development of superhydrophobic coating based on a single material, without the requirement of fluorination or silane treatment. In this work, the micro-arc oxidation(MAO) coating as transition layer can effectively enhance the bonding force of the superhydrophobic coating. The semiconductor@metal organic frameworks(MOFs) core-shell structure was synthesized by a simple self-templating method, and obtained ZnO@2-methylimidazole zinc salt(ZIF-8) nanorods array on magnesium(Mg)alloy. ZnO nanorods not only act as the template but also provide Zn^(2+) for ZIF-8. In addition, we proved that the ligand concentration,synthesis time and temperature are the keys to the preparation of ZnO@ZIF-8 nanorods. As we expect, the ZnO@ZIF-8 nanorods array can trap air in the gaps to form an air layer, and the coating exhibits superhydrophobic properties(154.81°). Excitingly, ZnO@ZIF-8 nanorods array shown a superhydrophobic property, without the requirement of fluorination or silane treatment. The results shown that the coating has good chemical stability and self-cleaning performance. Meanwhile, the corrosion resistance has been significantly improved, R_(ct) was increased from 1.044×10^(3) to 1.414×10^(6) Ω/cm^(2) and I_(corr) was reduced from 4.275×10^(-5) to 5.611×10^(-9)A/cm^2. Therefore, the semiconductor@MOFs core-shell structure has broad application prospects in anti-corrosion.

A Novel Dinuclear Copper(Ⅱ)Complex:Synthesis,Crystal Structure,Properties and Hirshfeld Surface Analysis

A novel copper complex [Cu2（L）（DMF）2]（1, H4L =（1 Z,N？Z）-3,5-dibromo-N？-（（3,5-dibromo-2-hydroxyphenyl）（hydroxy）methylene）-2-hydroxybenzohydrazonic acid which was synthesized by in-situ oxidation reaction derived from H2hdb（H2hdb = 6,6′-（（1 E,1？E）-hydrazine-1,2-diylidenebis（methanylylidene）） bis（2,4-dibromophenol）） has been synthesized and characterized by IR, elemental analysis（CHN）, TG and single-crystal X-ray diffraction. The single crystal belongs to monoclinic system, space group P21/c with a = 13.538（1）, b = 3.912（1）, c = 23.778（1）A°, β = 105.232（5）o, Mr = 857.08, V = 1214.9（1） A°^3, Z = 2, Dc = 2.343 g/cm^3, F（000） = 824, μ = 8.375 mm^–1, R = 0.0566, and w R = 0.1610. Compound 1 displays weak anti-ferromagnetic interactions through a η^1：η^1：η^1：η^1：η^1：η^1：μ2-L^4- bridging mode. Hirshfeld surface analysis revealed that complex 1 was supported mainly by Br···H and H···H intermolecular interactions.

A Chain Cadmium(Ⅱ) Coordination Polymer with Diacylhydrazide: Synthesis,Crystal Structure and Luminescent Property

A novel Cd（Ⅱ） coordination polymer with diacylhydrazide ligand N,N？-bis（3-methoxysalicyl）-2,6-pyridinedicarbohydrazide（H_6msphz）,[Cd_2（H_2msphz）（Py）_4]_n（1,Py = pyridine） has been synthesized through solvothermal reaction and structurally characterized by single-crystal X-ray diffraction,IR,TGA and PXRD investigations. It crystallizes in triclinic system,space group P1,with a = 11.0230（11）,b = 11.7264（15）,c = 17.3395（14） ？,α = 70.520（9）,β = 84.806（7）,γ = 81.965（9）°,V = 2089.9（4） ？~3,Dc = 1.638 gcm^（–3）,μ = 1.083 mm^（-1）,F（000） = 1032,Z = 2 and S = 1.040. In complex 1,the H_2msphz4-ligand uses not only its coordinated pocket to catch one Cd（Ⅱ） ion,but also its two terminal groups to chelate other two Cd（Ⅱ） ions,leading to the formation of a chain structure. The adjacent chains are further assembled together by two kinds of π-π interactions between the Py rings,resulting in the finial double layered supramolecular structure. In addition,complex 1 is found to show photoluminescence in the solid state at room temperature,which can be ascribed to the intraligand π→π＊ transitions.

A New Zn(Ⅱ)Coordination Polymer Constructed from 1,3,5-Benzenetricarboxylate Ligand Exhibiting Photoluminescence

The title Zn（Ⅱ） coordination polymer {[Zn2（BTC）（HBTC）（dpa）（Hdpa）]·3H2O}n（1,H3BTC = 1,3,5-benzenetricarboxylic acid,dpa = 4,4＇-dipyridylamine）,has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction,powder X-ray diffraction,IR spectroscopy and Fluorescence spectroscopy.Complex 1 belongs to the triclinic system,space group P1,a = 9.9415（4）,b = 13.5859（8）,c = 15.2987（5） A,α = 96.301（4）,β = 107.944（3）,γ = 103.575（4）°,V = 1873.48（14）A3,Z = 2,μ = 1.365 mm^-1,Dc = 1.672 g/cm^3,Mr = 943.44,F（000） = 964,the final R = 0.0314 and wR = 0.0710 with I 〉 2σ（I）.Complex 1 displays a two-dimensional bilayer coordination polymer.Complex 1 shows fluorescence in the solid state at room temperature.

Synthesis and electrochemical properties of spherically shaped LiVPO_(4)F/C cathode material by a spray drying-roasting method

LiVPO_(4) F has attracted increasing research interest in the field of Li-ion batteries due to its high working voltage platform and high theoretical energy density.However,the construction of stable LiVPO_(4) F cathode material with excellent electrochemical properties is still a major challenge.Herein,we successfully synthesized spherically shaped LiVPO_(4) F/C via a spray dryingroasting method.X-ray diffraction(XRD)and scanning electron microscopy(SEM)results indicate that the well crystallized LiVPO_(4) F/C with triclinic structure shows spherical morphology with an average diameter of 1-3μm.The spherically shaped LiVPO_(4) F/C delivers a discharge capacity of 137.9 mAh·g^(-1) at 0.1 C rate in the range of3.0-4.5 V and remains 91.4%capacity retention of its initial discharge capacity after 50 cycles.These results reveal that spray drying-roasting method is a promising approach to synthesize spherically shaped LiVPO_(4) F/C cathode material with stable crystal structure and excellent performance.

Fabrication of CuFe_(2)O_(4)/Bi_(12)O_(17)Cl_(2) photocatalyst with intrinsic p-n junction for highly efficient bisphenol A degradation

The construction and application of novel highly efficient photocatalysts have been the focus in the field of environmental pollutant removal.In this work,a novel CuFe_(2)O_(4)/Bi_(12)O_(17)Cl_(2)photocatalysts were synthesized by simple hydrothermal and chemical precipitation method.The fabricated CuFe_(2)O_(4)/Bi_(12)O_(17)Cl_(2)composite exhibited much higher photocatalytic activity than pristine CuFe_(2)O_(4)and Bi_(12)O_(17)Cl_(2)in the removal of bisphenol A(BPA)under visible-light illumination,which ascribed to the intrinsic p-n junction of CuFe_(2)O_(4)and Bi_(12)O_(17)Cl_(2).The photocatalytic degradation rate of BPA on CuFe_(2)O_(4)/Bi_(12)O_(17)Cl_(2)with an optimized CuFe_(2)O_(4)content(1.0 wt.%)reached 93.0%within 30 min.The capture experiments of active species confirmed that the hydroxyl radicals(·OH)and superoxide radicals(·O_(2)^(-))played crucial roles in photocatalytic BPA degradation process.Furthermore,the possible degradation mechanism and pathways of BPA was proposed according to the detected intermediates in photocatalytic reaction process.

Micro-vial Synthesis,Structure,Magnetic Properties and Hirshfeld Surface Analysis of a Penta-nuclear Fe(Ⅲ) Cluster

A new penta-nuclear Fe^Ⅲ cluster,[HN(C2H5)3]·[Fe5(timb)4(ATZ)4(μ3-O)2]·(H2O)5(1),(H2timb is 4-bromo-2-[(1H-tetrazol-5-ylimino)-methyl]-phenol;HATZ is 5-amino-1,2,3,4-tetrazole),was synthesized through micro-vial synthesis methods,which was characterized by elemental analysis,FT-IR spectra,X-ray single-crystal diffraction,thermogravimetric analysis.The single crystal belongs to the tetragonal system,space group √42d with a=0.19735(1),b=0.19735(1),c=0.26118(2)nm,Mr=1904.04,V=10.1724(10)nm^3,Z=4,Dc=1.118 g/cm^3,F(000)=3356,μ=2.314 mm^–1,R=0.0500 and wR=0.1151.The magnetic properties and Hirshfeld surface analysis of 1 were investigated and discussed in detail.

Temperature-controlled Structural Diversity of Two Cd(Ⅱ) Coordination Polymers Based on the Dicarboxylate Ligand

Two new 3-D Cd(Ⅱ) coordination polymers with p-phthalic acid (p-BDC) and 4,4′-dipyridylamine (4,4′-dpa),namely[Cd_(2)(p-BDC)_(2)(4,4′-dpa)_(2)]_(n) 1 and{[Cd(p-BDC)(4,4′-dpa)(H_(2)O)]·4H_(2)O}_(n) 2 were successfully synthesized under hydrothermal conditions at 120 and 140℃.They were characterized by single-crystal X-ray diffraction,IR,PXRD and TGA.It was further characterized by Hirshfeld surface (HS)analysis for complex 2.The luminescent properties of the complexes have also been investigated.

Preparation and Application of Polymerized High Internal Phase Emulsion Monoliths for the Preconcentration and Determination of Malachite Green and Leucomalachite Green in Water Samples

Polymerized high internal phase emulsion(polyHIPE)monoliths were prepared and applied as adsorbent materials for solid-phase extraction(SPE)of malachite green(MG)and leucomalachite green(LMG)from water samples.The polyHIPE monoliths were prepared by post-functionalization of monolithic surface with 6-aminocaproic acid(ACA)via ring opening reaction of epoxy groups in glycidyl methacrylate(GMA)-based polyHIPEs,and then applied to the preconcentration and determination of trace MG and LMG in environmental water samples by combing with high-performance liquid chromatog-raphy(HPLC).Taking MG and LMG as targets,main factors affecting SPE performance of the polyHIPE monoliths were investigated.Under the optimized conditions,the ACA-functionalized polyHIPE monoliths could effectively preconcentrate MG and LMG from 150 mL of water samples,and the recoveries of MG and LMG at three spiked levels were ranged from 84.8 to 97.4%with the relative standard deviations(RSDs)lower than 6%.The proposed method exhibited good linearity in the range of 2-200 ng mL^(-1),with low limits of detection of 17.0 and 8.7 pg mL^(-1)for MG and LMG,respectively.In addi-tion,the prepared ACA-modified polyHIPE monolith showed good durability and stability,and it could be reused for 200 cycles without obvious losing the extraction performance.

Erratum to:Borates as a new direction in the design of oxide ion conductors(vol 65,issue 10,page 2737,2022)

In the version of the article originally published in the volume 62,issue 10,2022 of Sci.china Mater.(page 2737-2745,https://doi.org/10.1007/s40843-022-2044-3).The chemical shift reported in Figure 5f for the^(11)B solid-state NMR spectra is incorrect because no parameter correction was performed during data processing.

In situ synthesized homochiral dysprosium-oxo clusters with threonine Schiff bases

Chiral high-nuclearity lanthanide(4f)clusters have shown fantastic properties in various fields.However,their synthesis is still of great challenge.Herein,we report two pairs of enantiomers of highnuclearity Dy-oxo clusters synthesized through in situ strategy.They are[Dy18(^(R/S)Hftp)4(^(R/S)H_(2)btp)4(μ2-OH)_(8)(μ3-OH)20(μ6-O)(NO_(3))_(4)(μ-H_(2)O)_(8)]·[solvents](1R and 1S)and[Dy9(^(R/S)Hftp)2(^(R/S)H_(2)btp)_(2)(OAc)_(6)(μ3-OH)_(10)(H_(2)O)_(6)](OAc)·[solvents](2R and 2S),where^(R/S)Hftp2−and^(R/S)H_(2)btp^(3−)represent in situ formed 2-formyl-6-[N-(threonine)iminomethyl]-4-methylphenol and 2,6-bis[N-(threonine)iminomethyl]-4-methylphenol anions,respectively.These in situ formed clusters were endowed with not only homochirality via introducing^(R/S)Hftp2−and^(R/S)H_(2)btp^(3−)ligands,but also rich oxo-bridges by controlling the hydrolysis of Dy^(III)ions.Different anions from DyIII salts further induced structural variation between two sets of clusters.1R and 1S feature an unprecedent four-blade propeller shaped{Dy18}core,whose centered octahedral{Dy6}unit are surrounded by four triangular{Dy3}units.Strikingly,they represent the second largest chiral 4f cluster species so far.2R and 2S display a sandglass-like{Dy9}skeleton that consist of two square pyramid{Dy5}units sharing a Dy^(III)vertex.Magnetic investigation revealed possible antiferromagnetic interactions between the Dy^(III)centers in these clusters.

Pressure-stabilized hexagonal perovskite-related isolated tetrahedral anion silicate La_(6)Sr_(3)Si_(6)O_(24)

The discovery of new perovskite compounds under high pressure mainly focuses on the ABO_(3)compositions and the compositions highly deviated from ABO_(3)are less explored.Here we demonstrate that the La_(6)Sr_(3)Si_(6)O_(24)silicate composition can be stabilized as a hexagonal perovskite-related structure with isolated tetrahedra anions under high pressure of 6 GPa.The compound adopts 9-layer shifted hexagonal perovskite-like structure with both B-cation and oxygen deficiencies and contains pseudo-cubic(c)(La/Sr)O_(2)layers and hexagonal(h)(La/Sr)O_(3)layers stacked according to(c hh)_(3)sequence.This structure features both B-cation vacancy ordering between the two consecutive hexagonal layers and oxygen vacancy ordering in c-(La/Sr)O_(2)layers,resulting in isolated tetrahedral Si O_(4)anions and ionic conduction behavior.This work demonstrates the practicability of accessing new perovskite-related functional materials from the compositions highly deviated from ABO_(3)under high pressure.

硼酸盐:氧离子导体设计的一个新方向

降低固体氧化物燃料电池(SOFCs)的工作温度正在推动新型氧离子导体材料的开发.在此,受氧离子导体材料结构共性的启发,基于Sr(Si/Ge)O_(3)材料中刚性(Si/Ge)_(3)O_(9)基团无法容纳氧空位,以及BO_(n)多面体在配位数、旋转、变形和连接上的巨大灵活性,我们首次通过计算预测和实验验证,报道了基于硼酸盐的新型氧离子导体材料(Gd/Y)_(1−x)-Zn_(x)BO_(3−0.5x).(Gd/Y)BO_(3)中的氧空位可以通过孤立的B_(3)O_(9)三元环形成B_(3)O_(8)结构单元来容纳,并通过B_(3)O_(9)和B_(3)O_(8)单元之间的氧交换合作机制来传输,而这些结构单元作为过渡态的打开和伸展则有助于氧的传输.这项研究为设计和开发新型氧离子导体开辟了新方向,有望从硼酸盐家族发现更多新的氧离子导体.