Two-dimensional polyaniline nanosheets via liquid-phase exfoliation

Two-dimensional（2D） organic nanomaterials are fascinating because of their unique properties and pentential applications in future optoelectronic devices.Polyaniline（PANI） has attracted much attention for its high conductivity,good environmental stability and unusual doping chemistry.We report on liquid-phase exfoliation of layered PANI films grown by electrochemical polymerization.Atomic force microscopy images demonstrate that few-or even mono-layer PANI nanosheets can be fabricated.The PANI nanosheets can be transferred onto a variety of surfaces,providing a promising route to their incorporation into a variety of devices for further studies and various applications.

Organic salt-assisted liquid-phase shear exfoliation of expanded graphite into graphene nanosheets

How to improve the efficiency of liquid-phase shear exfoliation(LPSE)for mass production of large-size graphene nanosheets still remains an ongoing challenge.In this work,we have developed a LPSE method using a rotor-stator mixer.It is quite simple and efficient by exfoliation of expanded graphite(EG)in Nmethyl-2-pyrrolidone(NMP)with the assistance of organic salts including sodium citrate,potassium citrate and sodium tartrate.The LPSE of EG in NMP can provide improved yields,up to 6 times as high as values from exfoliation of natural flake graphite(NFG).The additive of organic salts in NMP can make a further improvement in graphene yields,1.5 times higher than that obtained only in NMP.Remarkably,the yields of the as-exfoliated graphene are as high as 10%under optimal conditions,and up to 50%after multiple-cycle exfoliation.Organic salts in LPSE act as analogue grinding aids enhancing the applied shear forces and thus contributing to the improved efficiency of LPSE,but they do not intercalate into the interplanar spaces of graphite.This facile LPSE method should have excellent potential in the large scale production of graphene nanosheets for numerous applications.

Solvothermal-assisted liquid-phase exfoliation of large size and high quality black phosphorus

Black phosphorus(BP),especially for BP nanosheets,with unique layered structure among two dimensional(2D)materials has attracted much attention due to its outstanding physical properties,such as ultra-high mobility,in-plane anisotropic properties.However,the small horizontal-size of reported BP limits its applications in the integrated circuit or some functional devices.In this work,a solvothermalassisted liquid-phase exfoliation technique is firstly employed for preparing large size and high-quality BP nanosheets.In the high-polar acetonitrile solvent,solvothermal treatment weakens the Van der Waals forces of block BP.Together with the subsequently ultrasonic processing,effective exfoliation of large size and high-quality BP nanosheets are realized.The TEM,AFM and Raman results indicate that the prepared BP nanosheets are high quality with an average thickness of about 2 nm,and the horizontalsize is up to 10μm.This facile and effective method for exfoliated BP nanosheets provides a promising strategy for the exfoliation of other 2D materials.

Liquid-phase exfoliation of violet phosphorus for electronic applications

Large-scale production of two-dimensional(2D)materials still is a crucial point toward its practical applications.Violet phosphorus(VP)with a wide bandgap accelerates and broadens the potential applications of elemental phosphorus in optoelectronics.Here,we demonstrate the scalable production of solution-processable violet phosphorus flakes stably dispersed in several solvents.The exfoliated VP flakes exhibit thickness-dependent visible photoluminescence characteristics,which covers the shortcoming of black phosphorus.Meanwhile,the VP-based field-effect transistor reveals relatively competitive electrical properties to other liquid-phase exfoliated 2D materials.Our study paves the way for a wide range of applications of optical devices,energy storage,catalysis,and sodium batteries based on large-scale VP flakes.

MoS_(2)core-shell nanoparticles prepared through liquid-phase ablation and light exfoliation of femtosecond laser for chemical sensing

Molybdenum disulfide(MoS_(2))-based nanostructures are highly desirable for applications such as chemical and biological sensing,photo/electrochemical catalysis,and energy storage due to their unique physical and chemical properties.In this work,MoS_(2)core-shell nanoparticles were first prepared through the liquid-phase processing of bulk MoS2by a femtosecond laser.The core of prepared nanoparticles was incompletely and weakly crystalline MoS_(2);the shell of prepared nanoparticles was highly crystalline MoS_(2),which wrapped around the core layer by layer.The femtosecond laser simultaneously achieved liquid-phase ablation and light exfoliation.The formation mechanism of the core-shell nanoparticles is to prepare the nanonuclei first by laser liquid-phase ablation and then the nanosheets by light exfoliation;the nanosheets will wrap the nanonuclei layer by layer through van der Waals forces to form core-shell nanoparticles.The MoS_(2)core-shell nanoparticles,because of Mo-S bond breakage and recombination,have high chemical activity for chemical catalysis.Afterward,the nanoparticles were used as a reducing agent to directly prepare three-dimensional(3D)Au-MoS_(2)micro/nanostructures,which were applied as surface-enhanced Raman spectroscopy(SERS)substrates to explore chemical sensing activity.The ultrahigh enhancement factor(1.06×10^(11)),ultralow detection limit(10-13M),and good SERS adaptability demonstrate highly sensitive SERS activity,great ability of ultralow concentration detection,and ability to detect diverse analytes,respectively.This work reveals the tremendous potential of 3D Au-MoS_(2)composite structures as excellent SERS substrates for chemical and biological sensing.

Liquid-phase Exfoliated WS2-Graphene Composite Anodes for Potassium-ion Batteries

Tungsten disulfide(WS2) has been recognized as a promising anode material for rechargeable potassium-ion batteries(PIBs). However, its K-ion intercalation capacity is limited to ~60 mAh·g^(-1). Here, we report a WS2-graphene composite anode which is fabricated through simple filtration of liquid-phase exfoliated WS2 and graphene nanosheet delivers a significantly improved specific capacity of 137 mAh·g^(-1) at a current density of 10 mA·g^(-1). The composite anodes also exhibit remarkable rate capability and long-term cyclability over 500 cycles. These results highlight the WS2-graphene composite structure as a promising anode material for long lifespan rechargeable potassium-ion batteries.

Fluorographene with Narrow Lateral Size and Thickness Distributions Prepared for Enhancing Lubrication Performance of Bentonite Grease

Fluorographene(FG)with narrow lateral size and thickness distributions was prepared by a liquid-phase exfoliation method,based on liquid cascade centrifugation.The Rtec MFT-5000 tribo-meter was used to investigate the lubricating performance of bentonite grease enhanced by the as-prepared FG.The results showed that the coefficient of friction and the wear volume of bentonite grease with 0.3 wt%FG were decreased by 20.4%and 44.9%,respectively,as compared to those of the base grease.The main reason is that FG can promote the formation of the tribo-chemical reaction film consisting of complex carbon oxide,Fe_(2)O_(3)and FeF_(3)on the friction surface,which can remarkably improve the performance of friction reduction and prevent the appearance of severe wear.

Ultraviolet Photodetector based on Sr_(2)Nb_(3)O_(10) Perovskite Nanosheets

Liquid-phase exfoliation was employed to synthesize Sr_(2)Nb_(3)O_(10) perovskite nanosheets with thicknesses down to 1.76 nm.Transmission electron microscopy(TEM),atomic force microscope(AFM),X-ray photoelectron spectrometer(XPS),and other characterization techniques were used to evaluate the atomic structure and chemical composition of the exfoliated nanosheets.A UV photodetector based on individual Sr_(2)Nb_(3)O_(10) nanosheets was prepared to demonstrate the application of an ultraviolet(UV) photodetector.The UV photodetector exhibited outstanding photocurrent and responsivity with a responsivity of 3×10^(5) A·W^(-1) at 5 V bias under 280 nm illumination,a photocurrent of 60 nA,and an on/off ratio of 3×10^(2).

Properties and microstructure of oxide dispersion strengthened tungsten alloy prepared by liquid-phase method:a review

The addition of the second phase into tungsten can significantly refine the grain size of tungsten alloys,and also play a role in dispersion strengthening,thus improving the properties of tungsten alloy.As a preparation method of tungsten alloy powder,liquid-phase method avoids the disadvantage of mechanical alloying,and the obtained powder composition is accurate and controllable,with high purity and excellent uniformity.At present,the second phase particles used for dispersion strengthening tungsten alloys are mainly composed of oxides.Oxide particles can be synthesized and precipitated in nitrate solution through in situ chemical reaction,and are uniformly distributed in composite powder by mixing and stirring.Finally,the oxide dispersion strengthened tungsten alloy(ODS-W)was obtained by reduction and sintering.Liquid-phase methods for preparing ODS-W alloys include azeotropic distillation,sol-gel methods,freeze-drying,hydrothermal synthesis,spray-drying,etc.In this paper,several liquid-phase methods for preparing tungsten alloy composite powder precursors are reviewed,and their latest research progresses are discussed.In addition,the morphologies and properties of tungsten alloys prepared by different methods are compared,which provides guidance for preparing high-performance tungsten alloys.

化妆品去角质效果评价方法研究进展

皮肤角质层是表皮最为重要的组成结构,角质层太厚或太薄都会引起皮肤健康问题,因此化妆品去角质效果的全面、多维度的评价非常必要。《化妆品分类规则和分类目录》中对去角质的释义为有助于促进皮肤角质的脱落或促进角质的更新。从皮肤角质层的结构及其功能出发,详细介绍了脱落角质的测试方法、角质更新时间的追踪方法以及皮肤角质层表面和内部状态的评价方法,其中皮肤角质层状态评估方式又可以分为图像分析、仪器数据采集分析和主观评价3种方式,并且展望了化妆品去角质效果的评价体系的新发展方向。

硬脂酸法制备超细K_2La_2Ti_3O_(10)及其酸交换性质研究

A new stearic acid method(SAM) has been used to prepare ultrafine K2La2Ti3O10 nanocrystalline. Each state of synthesis process was followed by the use of FT IR analysis. The resulting materials have been characterized by means of XRD, TEM, BET surface area analysis. The acid exchanging property of the obtained product was also studied. The experimental results showed that comparing with the product of traditional solid state reaction, the particle size of the K2La2Ti3O10 synthesized by SAM is greatly reduced, BET surface area is high(more than 11.83m2· g- 1) and has different acid exchanging properties. It can be easily exfoliated in 2mol· L- 1 HNO3 solution.

铝合金剥蚀敏感性及其定量研究方法

介绍了铝合金剥蚀敏感性的 3种定量研究方法 :电化学阻抗法、腐蚀产物外推力测试法及电阻法 ,阐述了这3种方法的原理和特点 .报道了 2×××、5×××、7×××系及Al-Li合金的剥蚀敏感性与其热处理制度的关系及其影响机制 .

基于表面能理论的沥青-集料体系的粘附特性研究

基于表面自由能理论,采用接触角法测定2种沥青与4种集料的表面自由能参数,分别计算出各种沥青-集料体系的粘附功和剥落功,以表征沥青-集料体系的粘附性优劣;并采用冻融劈裂试验进行验证.结果表明:石灰岩集料与SK70改性沥青的粘附功最大,剥落功最小;花岗岩集料与SK基质沥青的粘附功最小,剥落功最大.此外,剥落功表征的沥青-集料体系的粘附性能与冻融劈裂试验表征的粘附性能基本一致;且沥青-集料体系的剥落功更能直观地定量评价沥青-集料体系的粘附性能.

热膨胀剥离法制备石墨烯及其表征

以-48um高纯鳞片石墨为原料，先采用Hummers法制备氧化石墨，再采用高温热膨胀剥离法制备石墨烯。利用x射线衍射（XRD）、傅里叶红外光谱（FT-1R）、原子力显微镜（AFM）、M吸附-脱附（BET）等研究了氧化石墨及石墨烯的晶体结构、表面官能团、表面形貌、比表面积、孔径分布等。XRD研究结果表明，氧化石墨层间距为0．94nnl，原有的石墨峰消失；热膨胀所得石墨烯（20=25．6°，d（002）=0．348nm）为无定形态。FT-IR分析表明，石墨氧化过程中结构层间形成大量含氧官能团，经高温还原后仅残存部分含氧官能团。石墨烯具有较高的比表面积（336．7m2／g），其厚度在0．4～0．7nm之间，为1～2层石墨烯。

高倍率无硫低温可膨胀石墨的电化学法制备

为使用低污染的方法制备低温可膨胀石墨(LTEG),以天然鳞片石墨(NFG)为原料,以高氯酸溶液为电解液,通过电化学法制备了起始膨胀温度低,低温膨胀容积大且不含硫的LTEG.探讨了电流密度、电解时间、电解液中HClO_4的质量分数和膨胀温度对膨胀容积(EV)的影响,采用FT-IR、TGA和XRD对制得的LTEG进行了研究.结果表明:电解液中HClO_4的质量分数可以低至50%,与化学法相比大幅降低,电解液易于循环使用,对环保有利;LTEG在200和950℃时的FV分别高达282和594 mL/g,具有高倍率、无硫和低温膨胀性能;LTEG表面有羰基和羧基生成,层间存在ClO_4^-和HClO_4插层物;在2θ为25.76°处的特征衍射峰强度非常弱,而在2θ为9.41°处有一宽峰,对应层间距为0.941 nm;在60~330℃之间发生明显热失重,失重率约为28%,在60~800℃之间的总热失重率约为35%.

飞机铝合金结构连接部位的腐蚀行为

简要阐述了飞机铝合金结构连接部位的腐蚀特点,采用加腐蚀试验方法研究了含有防腐涂层模拟件的腐蚀行为,在试验室条件下再现了服役期间飞机铝合金结构连接部位的腐蚀损伤历程,同时探讨了其腐蚀机理及其影响因素。结果表明,连接部位是飞机铝合金结构的腐蚀薄弱环节,是最容易出现腐蚀活性点和膜下腐蚀的区域,在腐蚀环境下连接部位缝隙处涂层最先出现鼓包和开裂,涂层剥落后金属基体有点蚀坑存在,随着腐蚀时间增加,点蚀向晶间腐蚀发展,最后出现剥蚀。

MnO_2/膨胀石墨纳米材料及其超级电容性能

采用溶胶-凝胶法制备了MnO2/膨胀石墨(MnO2/EG)纳米材料,分别利用扫描电镜、X射线衍射测试其表面形貌及结构,使用循环伏安和恒流充放电等表征其电化学性能。结果表明,制备的MnO2/EG纳米材料在6mol/L KOH电解质溶液中的比电容量为492F/g;2000次循环后,比容量仅损失1%,且充放电效率仍高于99%,表现出良好的电化学性能。

二维石墨相氮化碳纳米片的制备方法研究进展

石墨相氮化碳(g-C_3N_4)是一种不含金属的聚合物半导体光催化剂,具有独特的电子能带结构、优异的化学稳定性和热稳定性、良好的生物相容性等优点使其广泛应用于催化、生物和能源等领域。研究结果表明,与块体g-C_3N_4相比,二维g-C_3N_4纳米片不仅具有增强的本征性质,还能产生很多新的物理化学性质,拓宽了其应用领域。阐述近年来国内外层状材料g-C_3N_4的主要剥离方法,分析不同方法的优缺点,对其他层状材料的剥离具有借鉴意义。

新疆喀什地区维吾尔族女性人乳头状瘤病毒感染分析研究

目的调查喀什地区女性人群宫颈脱落细胞HPV感染情况、亚型分布及其特点。方法收集1 548例女性的宫颈脱落细胞标本,采用PCR-反向点杂交法检测23种HPV基因型,对HPV感染情况及其型别进行分析。结果 HPV感染阳性率为33.3%(485/1 548),其中HPV-16感染率19.4%;HPV42感染率10.3%;HPV52感染率9.9%;HPV58感染率7.6%;HPV53感染率7.2%;单一亚型感染率66.8%,多重感染率33.2%;41~50岁的女性人群中HPV感染率最高(43.3%),高于其他年龄组,且差异具有统计学意义(P<0.05)。结论喀什地区女性人群HPV感染以HPV16型为主,而且41~50岁的女性人群中HPV感染率最高,为喀什地区相关部门HPV的预防控制工作提供理论依据。

层状K-Fe-Ti氧化物的剥离及光催化性能

采用软化学法制备了具有层状结构的K-Fe-Ti氧化物K2.3Fe2.3Ti5.7O16,并用1mol/L稀硝酸对样品进行剥离。通过XRD、TEM等测试技术对剥离前后的样品进行表征,并研究了剥离后样品对甲基橙降解的光催化活性。结果表明,K2.3Fe2.3Ti5.7O16经过稀硝酸剥离后得到锯齿状或者梳子状的薄片结构,这种薄片结构在pH值小于2时对甲基橙的降解有较高的光催化活性,在太阳光照射100min后甲基橙降解率超过40%。