Electrolytic Preparation,Structure Characterization and Electro-chemical Performance of NiOOH

NiOOH was prepared by one-step electrolysis of spherical Ni(OH)2 and the effects of electrolysis pa-rameters were examined.The highly pure NiOOH was obtained after electrolysis at a current density of 60mA·g-1 and 30℃ with anodic potential controlled in the range of 1.73—1.85V(vs.Zn/ZnO)for 360min.The NiOOH sam-ples were characterized by X-ray powder diffraction(XRD)and scanning electron microscope(SEM)analysis.Re-sults indicate that the electrolysis product is spherical NiOOH doped with graphite.Charge and discharge tests show that the prepared NiOOH offers a discharge capacity of over 270mAh·g-1 at current density of 30mA·g-1 and can be directly used as cathode material of alkaline Zn/NiOOH batteries.Galvanostatic charge/discharge and cyclic volt-ammetry(CV)tests reveal good cycling reversibility of the NiOOH electrode.

Electrochemical Performance and Capacity Fading Mechanism of LiFePO4 at Different pH Aqueous Electrolyte Solutions

在一个包含 Li+ 水的电解质答案的 LiFePO4 的电气化学的稳定性极其依赖于水的答案的 pH 价值。pH 价值什么时候被增加到 11，在骑车之上在 LiFePO4 的能力显示出可观的腐烂。为褪色的能力负责的机制广泛地借助于周期的 voltammogram，交流阻抗，控告 / 解除，前 situ X 光检查衍射，和化学分析被调查。LiFePO4 是相对在有 pH=7 的 LiNO3 水的答案电气化学地稳定。但是在水的电解质的 LiFePO4 的电气化学的表演在器官的电解质低于那。它被归因于李和 Fe 的损失， P 溶解在在水的媒介的延长费用分泌物期间。A 猛抛在 LiFePO4 电极的表面上被形成。它导致水晶的结构，大电极极化，并且能力褪色的变化。

Effects of electrochemical oxidation on surface and mechanical properties of dry-jet wet spun carbon fibers

The surface of dry-jet wet spun carbon fibers(CFs)is relatively smooth compared with those of wet spun CFs,which results in weak interfacial interactions between the fiber and the polymer resin.A surface functionalization treatment is particularly important to unleash the full potential of the superior mechanical properties of dry-jet wet spun CFs.In this study,the effects of electrochemical oxidation treatment time and current density on the surface structures and the mechanical properties of dry-jet wet spun CFs were investigated.The interlaminar shear strength of the CFs improves significantly from 69 to 84 MPa after 120 s of treatment.Further structural analysis reveals that the improvements are due to the addition of oxygen-containing functional groups and the optimization of the morphology on the surface of the CFs.

Effect of Strain and Chloride Concentration on Pitting Susceptibility for Type 304 Austenitic Stainless Steel

为类型 304 不锈钢的 pitting 危险性上的紧张和氯化物集中的效果在经常的紧张下面用电气化学的技术在 situ 被学习。影响因素 f 向前被带在 pitting 上珍视紧张的效果。在在紧张层次下面的各种各样的氯化物集中的类型 304 不锈钢的 pitting 行为 0% ， 10% ，和 30% 被调查。Potentiostatic 极化技术被用来学习氯化物集中怎么影响了腐蚀电流密度。结果显示 f 实质地增加了，当氯化物集中是超过 90 mg · L 时， pitting 潜力显著地变化了 ? 1。在，上面提及的紧张的三个层次下面，氯化物集中在 463 mg · L 下面 ? 1,121 mg · L ? 1，和 98 mg · L ? 1 分别地， pitting 潜力向确实变了并且，被动电影变得更稳定。当紧张低于 10% 时，当紧张增加了，类型 304 不锈钢的 pitting 危险性极大地变化了，而当紧张是超过 10% 时，危险性仅仅有点变化了。

The Enrichment of Chloride Anion in the Occluded Cell and Its Effect on Stress Corrosion Crack of 304 Stainless Steel in Low Chloride Concentration Solution

在为在低氯化物集中答案的类型 304 奥氏体的不锈钢的堵塞房间(OC ) 以内的氯化物阴离子的丰富借助于模仿的 OC 被调查了。类型 304 不锈钢的压力腐蚀快克(SCC ) 上的氯化物阴离子的丰富的影响被学习了。氯化物阴离子移植的数量与通过阳极流动的费用成正比，这被观察。拥有到氯化物阴离子的丰富的效果，低氯化物集中答案能为类型 304 不锈钢导致 SCC。

Preparation of indium tin oxide targets with a high density and single phase structure by normal pressure sintering process

The present work mainly describes the technology for preparing indium-tin oxide （ITO） targets by cold isostatic pressing （CIP） and normal pressure sintering process. ITO powders were produced by chemical co-precipitation and shaped into an ITO green compact with a relative density of 60% by CIP under 300 MPa. Then, an ITO target with a relative density larger than 99.6% was obtained by sintering this green compact at 1550℃ for 8 h. The effects of forming pressure, sintering temperature and sintering time on the density of the target were inves- tigated. Also, a discussion was made on the sintering atmosphere.

Direct Ink Writing of Highly Conductive MXene Frames for Tunable Electromagnetic Interference Shielding and Electromagnetic Wave-Induced Thermochromism

The highly integrated and miniaturized next-generation electronic products call for high-performance electromagnetic interference(EMI)shielding materials to assure the normal operation of their closely assembled components.However,the most current techniques are not adequate for the fabrication of shielding materials with programmable structure and controllable shielding efficiency.Herein,we demonstrate the direct ink writing of robust and highly conductive Ti3C2Tx MXene frames with customizable structures by using MXene/AlOOH inks for tunable EMI shielding and electromagnetic wave-induced thermochromism applications.The as-printed frames are reinforced by immersing in AlCl_(3)/HCl solution to remove the electrically insulating AlOOH nanoparticles,as well as cross-link the MXene sheets and fuse the filament interfaces with aluminum ions.After freeze-drying,the resultant robust and porous MXene frames exhibit tunable EMI shielding efficiencies in the range of 25-80 dB with the highest electrical conductivity of 5323 S m−1.Furthermore,an electromagnetic wave-induced thermochromic MXene pattern is assembled by coating and curing with thermochromic polydimethylsiloxane on a printed MXene pattern,and its color can be changed from blue to red under the high-intensity electromagnetic irradiation.This work demonstrates a direct ink printing of customizable EMI frames and patterns for tuning EMI shielding efficiency and visualizing electromagnetic waves.

Super-Tough and Environmentally Stable Aramid Nanofiber@MXene Coaxial Fibers with Outstanding Electromagnetic Interference Shielding Efficiency

Although electrically conductive and hydrophilic MXene sheets are promising for multifunctional fibers and electronic textiles,it is still a challenge to simultaneously enhance both conductivity and mechanical properties of MXene fibers because of the high rigidity of MXene sheets and insufficient inter-sheet interactions.Herein,we demonstrate a core-shell wet-spinning methodology for fabricating highly conductive,super-tough,ultra-strong,and environmentally stable Ti_(3)C_(2)T_(x) MXene-based core-shell fibers with conductive MXene cores and tough aramid nanofiber(ANF)shells.The highly orientated and low-defect structure endows the ANF@MXene core-shell fiber with supertoughness of~48.1 MJ m^(-3),high strength of~502.9 MPa,and high conductivity of~3.0×10^(5)S m^(-1).The super-tough and conductive ANF@MXene fibers can be woven into textiles,exhibiting an excellent electromagnetic interference(EMI)shielding efficiency of 83.4 dB at a small thickness of 213μm.Importantly,the protection of the ANF shells provides the fibers with satisfactory cyclic stability under dynamic stretching and bending,and excellent resistance to acid,alkali,seawater,cryogenic and high temperatures,and fire.The oxidation resistance of the fibers is demonstrated by their wellmaintained EMI shielding performances.The multifunctional core-shell fibers would be highly promising in the fields of EMI shielding textiles,wearable electronics and aerospace.

MONOMER REACTIVITY RATIO AND THERMAL PERFORMANCE OFα-METHYL STYRENE AND GLYCIDYL METHACRYLATE COPOLYMERS

Synthesis and characterization of the copolymers （PAG） of α-methyl styrene （AMS） and glycidyl methacrylate （GMA） are presented. The copolymers of PAG were characterized by gel permeation chromatography （GPC）, Fourier transform infrared spectroscopy （FTIR）, nuclear magnetic resonance （^1H-NMR） and thermogravimetery （TG）. Based on the copolymer compositions determined by ^1H-NMR, the reactivity ratios of AMS and GMA were found to be 0.105 ± 0.012 and 0.883 ± 0.046 respectively by Kelen-Tudos method. TG revealed that thermal stability of the copolymers decreased with increasing the AMS content in the copolymers, which indicated that the degradation was mainly caused by the chain scission of AMS-containing structures. Under heating, the copolymers depolymerize at their weak bonds and form chain radicals, which could further initiate other chemical reactions.

Synthesis and characterization of novel multifunctional epoxy resin

A novel multifunctional epoxy resin was synthesized by polyphenol and epichlorohydrin. The structure and molecular weight of the multifunctional epoxy were characterized by FTIR and ESI-MS. DSC and DMTA were used to investigate the thermal property of multifunctional epoxy cured by DDS. The thermal resistance of the synthesized multifunctional epoxy was much better than a standard diglycidyl ether of bisphenol-A epoxy.

One-step hydrothermal synthesis of 2,5-PDCA-containing MgAl-LDHs three-layer composite coating with high corrosion resistance on AZ31

The addition of 2,5-pyridinedicarboxylic acid(2,5-PDCA)to the Mg-Al LDH coating,which was prepared by one-step hydrothermal synthesis,had extremely enhanced the corrosion protection of AZ31 Mg alloy,although the 2,5-PDCA could not be intercalated into the interlayer spacing.The corrosion current density of 0.05 mol L^(−1)2,5-PDCA LDH containing LDH coating is 3.18 nA cm^(−2),reduced by two orders of magnitude compared to the LDH coating without inhibitor,and the corrosion inhibition efficiency of the coating is 98.05%.The coating formed on the surface of AZ31 was peeled off from the substrate by using a mechanical method and SEM observation of the cross-section showed that the coating consisted of three different layers.The innermost layer is a thick layer that consists of Mg(OH)_(2)and the intermediate layer is LDH,which is vertical to the substrate and the outmost layer is a thin but very dense deposit layer of LDH agglomerates with complexes of 2,5-PDCA and Mg.This kind of sediment/LDH/Mg(OH)_(2)three-layer composite structure was accountable for the increase in the corrosion resistance of AZ31 Mg alloy.

Properties and structure of RE-Ni-W-P-SiC composite coating prepared by impulse electrodeposition

The properties and structure of electrodeposited RE (CeO2)-Ni-W-P-SiC composite coating were investigated. The results show that the hardness and electrodepositing speed of composite coatings obtained at an impulse current are higher than those at a direct current. The hardness and wear resistance of the coating are obviously increased by adding RE and SiC. The hardness of the coating increases with the increase of treatment temperature and current density, and reaches the optimum value at 400 ℃ and at 10 A/dm2, respectively. The optimum operation parameters of electrodeposition of the composite coating are as follows: pH value is 4.5, bath temperature is 65 ℃ , and current density is 10 A/dm2.

Auxiliary Ligand-tuned Structural Variation of Cd(Ⅱ)Coordination Polymers:Synthesis,Crystal Structures and Luminescent Properties

Two new Cd（Ⅱ） coordination polymers, [Cd（PT）（1,4-BDC）0.5]n （1） and [Cd（PT） （1,3-BDC）0.5]n （2） （HPT = 3-（pyridin-2-yl）-1,2,4-triazole, 1,4-H2BDC = 1,4-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid）, have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction as well as elemental analysis and IR. Complexes 1 and 2 are both three-dimensional coordination polymers with two-dimensional sheet structures bridged by the deprotonated carboxylate ligands. In 1, 1,4-BDC2- bridges the layered network to generate a quadrangular framework, and 2 owns a sexangular framework, which was caused by the different steric hindrance between 1,4-BDC^2- and 1,3-BDC^2-. Their thermal stabilities and photoluminescent properties have been also investigated.

Preparation and characterization of uniform circinate aggregates of sheet ZnO nanoparticles

Uniform circinate aggregates of sheet ZnO nanoparticles with a specific surface area of 24 m^2·g^-1 were prepared by the direct precipitation method.The circinate aggregates were hexagonal ZnO,with the wall thickness ranging from 0.5 to 1 μm and the diameter ranging from 5 to 10 μm.The backs of the circinate aggregates were regularly arranged by numerous sheet ZnO nanoparticles with a thickness of 30-80 nm and a diameter of 300-400 nm.The precursors were aggregates of sheet Zn5（CO3）2（OH）6 nanoparticles,which were decomposed into ZnO by calcining in air in the range of 200-285°C,and the ZnO retained the similar special structure.The C2H5OH content had a significant effect on the formation of sheet ZnO.The centripetal force,the Van der Waals force,and the hydrogen bond were deduced as the driving forces of the formation of circinate.

NOVEL HYPERBRANCHED POLY(PHENYLENE OXIDE)S WITH PHENOLIC TERMINAL GROUPS: EFFECTS OF REACTION TIME AND CORE MOLECULES ON THE MOLECULAR WEIGHT AND POLYDISPERSITY

A novel hyperbranched poly（phenylene oxide） （HPPO） with phenolic terminal groups was prepared from 4-bromo-4＇,4＂-dihydroxytriphenylmethane as AB2 monomer in dimethylsulfoxide （DMSO） via a modified Ullmann reaction. The molecular weight and polydispersity （PD） of the resulting polymers increased with increasing reaction time. In the presence of core molecules （bisphenol A and 1,3,5-trihydroxybenzene）, which have the similar molecular backbones to the reactive monomer, the molecular weight could be controlled by varying the core-to-monomer ratio. Incorporation of a very small amount of core molecules could lead to a higher molecular weight as compared with that without the addition of core molecules. However, when the core content reached certain extent, the molecular weight would decrease with the further increase in the core content. A new similar behavior of control over the PD was also obtained. The resulting polymers were characterized by ^1H-NMR, ^13C-NMR, FT-IR, and GPC.

Studies on Thermal Stability and Fluid Property of PVC Filled with Hydrotalcite

Hydrotalcite can act as a co-stabilizer with other main stabilizer for poly(vinyl chloride)(PVC). The thermal stability and fluid property of PVC filled with hydrotalcite surface-treated with titanate and silane were studied in this work. Organic Sn is a main stabilizer and hydrotalcite is a stabilizing assistant. The stability of the PVC resin mixed with organic Sn and hydrotalcite is better than that of the PVC resin mixed with organic Sn alone. It is shown that the PVC resin filled with hydrotalcite possesses a better static and dynamic heat stability. Moreover, hydrotalcite can improve the fluid property of PVC, which is advantageous to the processing of PVC, and the optimum content of hydrotalcite is about 1%-2%(mass fraction).

Advancing green energy solution with the impetus of COVID-19 pandemic

The global energy system needs a revolutionary transition from today’s fossil fuel to a low carbon energy system by having deep carbonization in all energy demand sectors.Especially in the transport sector,fossil fuel-based vehicles contribute to a more massive amount of greenhouse gas emissions(GHG),mainly carbon dioxide(CO_(2))and particulate matter(PM2.5),affecting human health,society,and the climate system.Hydrogen and fuel cell technology is a promising low carbon transition pathway that supports GHG mitigation and achieves sustainable development.Although hydrogen and fuel cells are assuring,fuel cell vehicle expensiveness and the high cost of hydrogen production with the low carbon footprint are significant hindrances for its widespread deployment.Besides the situation above,the present corona virus(COVID-19)has devastated our global economy and ramps down the future of fossil fuel.It provides opportunities to rethink and reshape our energy system to a low carbon footprint.By utilizing the situation,governments and policymakers need to eliminate fossil fuel and invest in the hydrogen and fuel cell technologies deployment as future energy systems.This review article provides a technical overview of a low carbon energy system,production,and end-use service in a hydrogen economy perspective for developing a sustainable energy future.The techno-economic analysis of the different hydrogen production routines and fuel cell vehicles and their infrastructures are primarily focused.Finally,a long-term policy alignment was outlined to advance the hydrogen energy system for post-COVID-19 in the United Nation’s(UN)sustainable development goals framework.

Synthesis and Properties of Non-isocyanate Crystallizable Aliphatic Thermoplastic Polyurethanes

A simple non-isocyanate route synthesizing thermoplastic polyurethanes（TPUs） with good thermal and mechanical properties is described. Melt transurethane polycondensation of dimethyl 1,6-hexamethylene dicarbamate with 1,4-butanediol and 1,6-hexanediol was conducted at different molar ratios under the catalysis of tetrabutyl titanate. A series of crystallizable non-isocyanate TPUs with high molecular weight were prepared. The TPUs were characterized by gel permeation chromatography, FT-IR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, AFM, and tensile tests. The TPUs exhibited Mn ranging from 12 500 to 26 400 g/mol, Mw from 16 700 to 56 400 g/mol, Tm up to 151.4 °C, and initial decomposition temperature over 241.8 °C. Their tensile strength reached 42.99 MPa with a strain at break of 30.00%. TPUs constructed simply with butylene, hexylene, and urethane linkages were successfully synthesized through a non-isocyanate route.

A comparative study of polymer nanocomposites containing multi-walled carbon nanotubes and graphene nanoplatelets

Featuring exceptional mechanical and functional performance, MWCNTs and graphene(nano)platelets(GNPs or Gn Ps;each platelet below 10 nm in thickness) have been increasingly used for the development of polymer nanocomposites. Since MWCNTs are now cost-effective at US$30 per kg for industrial applications, this work starts by briefly reviewing the disentanglement and surface modification of MWCNTs as well as the properties of the resulting polymer nanocomposites. GNPs can be made through the thermal treatment of graphite intercalation compounds followed by ultrasonication;GNPs would have lower cost yet higher electrical conductivity over 1,400 S cmthan MWCNTs. Through proper surface modification and compounding techniques, both types of fillers can reinforce or toughen polymers and simultaneously add anti-static performance. A high ratio of MWCNTs to GNPs would increase the synergy for polymers. Green, solvent-free systhesis methods are desired for polymer nanocomposites. Perspectives on the limitations, current challenges and future prospects are provided.

Crystal Structures and Luminescent Properties of Three Coordination Polymers Based on 2,5-Furandicarboxylic Acid Ligand and 1,10-Phenanthroline

Three new coordination polymers,namely [Zn（FDA）（phen）（H2O）·H2O]n（1）,[Cd（HFDA）（phen）2（NO3）]（2） and [Cd（FDA）（phen）]n（3）（H2FDA = 2,5-furandicarboxylic acid,phen = 1,10-phenanthroline） have been synthesized by the solvothermal method and characterized by elemental analysis,IR,powder X-ray diffraction,thermogravimetric analysis and X-ray single-crystal diffraction analysis.For 1,the neighboring Zn^2＋ ions are bridged by FDA2-as linkers to form one-dimensional（1D） chains,and phen ligands are as the terminal ligands.Furthermore,the 1D chains are packed into a three-dimensional（3D） supramolecular structure through hydrogen bonds and π-π interactions.For 2,the H2FDA ligand is partial deprotonation,which is a rare phenomenon among other coordination polymers based on H2FDA.Under the synergetic effect of phen ligands and the partial deprotonation of H2FDA,the structure of 2 is discrete.For 3,the Cd^2＋ ions are linked by two carboxylates of FDA^2-ligand to give rise to 1 D zig-zag chains,and phen ligands chelate the Cd^2＋ ions like 1.In addition,solid-state luminescent spectra of three coordination polymers were also studied at room temperature.