介孔及碳纳米材料
介孔材料
有序介孔材料有序介孔材料是上世纪90年代迅速兴起的新型纳米结构材料，它一诞生就得到国际物理学、化学与材料学界的高度重视，并迅速发展成为跨学科的研究热点之一。
有序介孔材料虽然目前尚未获得大规模的工业化应用，但它所具有的孔道大小均匀、排列有序、孔径可在2－50nm范围内连续调节等特性，使其在分离提纯、生物材料、催化、新型组装材料等方面有着巨大的应用潜力。
化工领域有序介孔材料具有较大的比表面积，相对大的孔径以及规整的孔道结构，可以处理较大的分子或基团，是很好的择形催化剂。
特别是在催化有大体积分子参加的反应中，有序介孔材料显示出优于沸石分子筛的催化活性。
因此，有序介孔材料的使用为重油、渣油等催化裂化开辟了新天地。
有序介孔材料直接作为酸碱催化剂使用时，能够改善固体酸催化剂上的结炭，提高产物的扩散速度，转化率可达90％，产物的选择性达100％。
除了直接酸催化作用外，还可在有序介孔材料骨架中掺杂具有氧化还原能力的过渡元素、稀土元素或者负载氧化还原催化剂制造接枝材料。
这种接枝材料具有更高的催化活性和择形性，这也是目前开发介孔分子筛催化剂最活跃的领域。
有序介孔材料由于孔径尺寸大，还可应用于高分子合成领域，特别是聚合反应的纳米反应器。
由于孔内聚合在一定程度上减少了双基终止的机会，延长了自由基的寿命，而且有序介孔材料孔道内聚合得到的聚合物的分子量分布也比相应条件下一般的自由基聚合窄，通过改变单体和引发剂的量可以控制聚合物的分子量。
并且可以在聚合反应器的骨架中键入或者引入活性中心，加快反应进程，提高产率。
生物医药领域一般生物大分子如蛋白质、酶、核酸等，当它们的分子质量大约在1～100万之间时尺寸小于10nm，相对分子质量在1000万左右的病毒其尺寸在30nm左右。
有序介孔材料的孔径可在2－50nm范围内连续调节和无生理毒性的特点使其非常适用于酶、蛋白质等的固定和分离。
实验发现，葡萄糖、麦芽糖等合成的有序介孔材料既可成功的将酶固化，又可抑制酶的泄漏，并且这种酶固定化的方法可以很好地保留酶的活性。
多孔碳纳米材料的分类、制备及应用
多孔碳纳米材料的分类、制备及应用孙镇镇/文【摘要】多孔碳纳米材料的孔径可以在微孔、介孔和大孔很宽的范围内进行调控，并且在一种碳材料中可以同时含有多级孔结构；依赖于合成途径，多孔碳的孔道可以有序或无序；形貌也具有多样性，可以是膜、球、纤维、短棒、单晶和体材料等多种形貌。
多孔碳材料独特的结构和性质，使之在气体和液体的分离、水处理、空气净化、生物和能源等诸多领域都具有广泛的应用前景。
本文主要介绍了多孔碳纳米材料的分类，重点阐述了多孔碳纳米材料的制备方法，并对其应用进行了展望。
【关键词】多孔碳纳米材料分类；制备方法；应用前景多孔碳纳米材料是指具有不同孔结构的碳纳米材料，其孔径可以根据实际应用的要求(如所吸附分子尺寸等)进行调控，使其尺寸处于纳米级微孔至微米级大孔之间。
多孔碳纳米材料具有碳材料的性质，如化学稳定性高、导电性好、价格低廉等优点；同时，孔结构的引入使其同时具有比表而积大、孔道结构可控、孔径可调等特点。
多种形态的活性炭是这类材料的典型例子，它们在气体和液体的精制、分离以及水处理、空气净化、色谱分析、催化和光催化及能量存储等领域得到了广泛的应用。
1.多孔碳纳米材料的分类1.1根据孔直径分类按照国际纯粹与应用化学联合会(IUPAC)的定义，可以根据多孔碳材料的孔直径将其分为三类:微孔(小于2nm)；介孔(2～50nm)和大孔(大于50nm)。
1.2根据结构特点分类根据多孔碳材料的结构特点，又可以将其分为无序多孔碳材料和有序多孔碳材料。
其中无序多孔碳材料的孔道不是长程有序，孔道形状不规则，孔径大小分布范围宽。
有序多孔碳材料具有孔道有序性，孔道形状和孔径尺寸可以得到很好的控制，且孔径分布范围窄。
在有序多孔碳材料中研究比较多的材料是有序介孔碳，如CMK-3，其孔径在介孔范围内，一般可以利用有序介孔二氧化硅SBA-15作为硬模板合成而得。
25中国粉体工业 2019 No.52.多孔碳纳米材料的制备方法多孔碳纳米材料的制备方法较多，归纳起来有以下几类:2.1 模板法模板法是用已可直接制备材料的形貌来控制制备其他材料形貌的方法。
介孔材料简介
介孔材料简介摘要：介孔材料作为一种新兴的材料在光化学、催化及分离等领域具有十分重要的应用,是当今研究的热点之。
本文阐述了介孔材料的研究进展,概述了介孔材料的分类及合成机理,并展望了介孔材料的应用前景，并简要介绍了孔径调节以及改性方法。
关键词：介孔材料，模板法，溶胶-凝胶法，合成机理，孔径调节Research development of mesoporous materials Abstract:Mesoporousmaterial is of much use in the fields of photochemistry, catalyst and separationetc, and it is one of hot spots of research. The research p rogress of the mesoporous materials is reviewed in this paper. And the classification and synthesis mechanism of the mesoporousmaterials are also outlined. The potential application foreground of the mesoporousmaterial is discussed as well.And briefly describes the aperture adjustment and modification methods.Key words：mesoporousmaterials; template method; sol - gel methods synthesis mechanism ;aperture adjustment1 前言人类社会的进步与材料科学的发展密切相关[ 1, 2 ],尤其是近几十年中,出现了许多具有特殊功能的新材料,其中介孔材料就是一种。
原位限域生长策略制备有序介孔碳负载的超小MoO_(3)纳米颗粒
Vol.42 2021年5月No.51589~1597 CHEMICAL JOURNAL OF CHINESE UNIVERSITIES高等学校化学学报原位限域生长策略制备有序介孔碳负载的超小MoO3纳米颗粒王常耀，王帅，段林林，朱晓航，张兴淼，李伟（复旦大学化学系,上海200433）摘要采用原位限域生长策略制备了一系列有序介孔碳负载的超小MoO3纳米颗粒复合物(OMC-US-MoO3).其中,有序介孔碳被用作基质来原位限域MoO3纳米晶的生长.依此方法制备的MoO3纳米晶具有超小的晶粒尺寸(<5nm),并在介孔碳骨架内具有良好的分散度.制得的OMC-US-MoO3复合物具有可调的比表面积(428~796m2/g)、孔容(0.27~0.62cm3/g)、MoO3质量分数(4%~27%)和孔径(4.6~5.7nm).当MoO3纳米晶的质量分数为7%时,所得样品OMC-US-MoO3-7具有最大的孔径、最小的孔壁厚度和最规整的介观结构.该样品作为催化剂时,表现出优异的环辛烯选择性氧化性能.关键词有序介孔碳；氧化钼纳米晶；纳米材料；限域生长中图分类号O611.4文献标志码AIn situ Confinement Growth Strategy for Ordered Mesoporous CarbonSupport Ultrasmall MoO3NanoparticlesWANG Changyao，WANG Shuai，DUAN Linlin，ZHU Xiaohang，ZHANG Xingmiao，LI Wei*（Department of Chemistry，Fudan University，Shanghai200433，China）Abstract Ultrasmall particle sizes and excellent dispersity of the MoO3active species on support majorly dominate their catalytic performances.Herein，a series of ordered mesoporous carbon support ultrasmall mo⁃lybdena nanoparticles（OMC-US-MoO3）composites was synthesized through an in situ confinement growth strategy.Ordered mesoporous carbon was used as the matrix to in situ confine the growth of MoO3nanocrystals. The obtained MoO3nanocrystals show ultrasmall particle sizes（<5nm）and excellent dispersity on the meso-porous carbon frameworks.The obtained OMC-US-MoO3exhibits tunable specific surface areas（428―796 m2/g），pore volumes（0.27―0.62cm3/g），MoO3contents（4%―27%，mass fraction）and uniform pore sizes （4.6―5.7nm）.As a typical example，the obtained sample with7%MoO3（denoted as OMC-US-MoO3-7）shows the largest pore size，smallest thickness of pore wall and most regular mesostructures.When being used as a catalyst，the OMC-US-MoO3-7exhibits an excellent catalytic activity for selective oxidation of cyclooctene with a high stability.Keywords Ordered mesoporous carbon；MoO3nanocrystal；Nanomaterials；Confinement growthdoi：10.7503/cjcu20200303收稿日期：2020-05-28.网络出版日期：2020-09-24.基金项目：国家自然科学基金(批准号:21975050)、国家重点研发计划纳米科技重点专项(批准号:2016YFA0204000, 2018YFE0201701)和中国博士后科学基金(批准号:2019M651342)资助.联系人简介：李伟,男,博士,教授,主要从事介孔材料的合成及应用研究.E-mail:*******************.cn1590Vol.42高等学校化学学报Epoxides，an important industrial chemicals，has been widely used in the fields of food additives，phar⁃maceutical intermediates，etc.［1，2］.Catalytic epoxidation of olefin is one of the essential route to produce epo-xides，which oxygenation of carbon-carbon double bond to form cyclic epoxide groups.The kind of catalyst plays a key role on the epoxidation reaction.Among all catalysts，precious metal of gold based one illustrates high activity for olefin epoxidations［3，4］.However，gold is limited resource and very expensive，even though it shows high conversion efficiency.Molybdenum oxide（MoO3），as one of the low cost，non-toxic and environ⁃mentally benign transition metal oxides，is widely used as heterogeneous catalysis for Friedel-Crafts alkyla⁃tion［5］，hydrogenation reaction［6，7］，epoxidation reaction［8，9］，hydrogen evolution reaction［10］，electrochemical energy storage for lithium-ion batteries［11，12］，and gas sensors［13，14］，etc..Gratifyingly，MoO3has been reported by several groups which have high activity for epoxidation of olefins in recent years［15，16］.It is obvious that the size and morphology of MoO3active species are critical factors that affect their prop⁃erties for application［17~20］.However，the synthesis and reaction process often easily causes serious sintering，migration and agglomeration of the MoO3nanoparticles，leading to the degradation of catalytic activity.Sup⁃ports are necessary for the immobilization of active species.Carbon has been widely used as an outstanding matrix to control the size and dispersity of supported metal oxides attributing to its advantages of intrinsical chemical inertness，high thermal stability，non-toxic and wide-sources［21~23］.Molybdena supported carbon have been reported and show excellent performance as the catalyst for cyclooctene epoxidation［24，25］.Recently，Chen group［26］fabricatedγ-Fe2O3@C@MoO3core-shell structured nanoparticles as a magnetically recyclable catalyst for the epoxidation reaction of olefins.The coated carbon layer play an efficient role for the stabiliza⁃tion of magnetic core.Biradar group［8］also reported a carbon microspheres-supported molybdena nanoparticles catalyst which also show outstanding effect for the epoxidation of olefins.However，above-mentioned catalysts are less porosity.Porous supports，especially，mesoporous carbon have been reported on many catalytic areas because of its large surface area，pore volume and pore size，which can not only improve the load capacity but also enlarge the reaction progress，where the diffusion process may be the rate-limiting step［26~28］.Up to now，it is still urgent to fabricate mesoporous carbon supported MoO3catalyst with ultrasmall particle size and excel⁃lent dispersity.Herein，we construct an ordered mesoporous carbon support ultrasmall MoO3nanoparticles（OMC-US-MoO3）composites via an in situ confinement growth strategy.In this strategy，the ordered mesoporous carbon works as a matrix to in situ confine the growth of MoO3nanocrystals.The obtained MoO3nanocrystals show ultrasmall particle size（<5nm）and excellent dispersity on the mesoporous carbon frameworks.The content （mass fraction）of MoO3can be tuned from4%to27%.The obtained OMC-US-MoO3shows tunable specific surface areas（428―796m2/g），pore volumes（0.27―0.62cm3/g）and uniform pore size（4.6―5.7nm）.As a typical example，the obtained sample with7%MoO3（denoted as OMC-US-MoO3-7）shows largest pore size，smallest thickness of pore wall and most regular mesostructures.When being used as a catalyst，the OMC-US-MoO3-7exhibits an excellent catalytic activity for selective oxidation of cyclooctene with a high stability.1Experimental1.1Chemicals and MaterialsPluronic F127（EO106PO70EO106，M w=12600）was purchased from Aldrich.All others chemicals were obtained from Aladdin company and used directly.Deionized water was used in all experiments.1.2Synthesis of Ordered Mesoporous Carbon Support Ultrasmall Molybdena NanoparticlesIn detail synthesis procedure，1.0g of Pluronic F127powders was added into10.0g of ethanol solution and stirred to a homogeneous clear solution at40℃.Afterwards，5.0g of20%（mass fraction）preformedNo.5王常耀等：原位限域生长策略制备有序介孔碳负载的超小MoO 3纳米颗粒phenolic resins ethanol solution and 1.0mL of peroxomolybdenum precursor solution were added into the ho⁃mogeneous system （5—200mg/mL ）.The preformed phenolic resins was synthesized based on the reported method ［27，28］.Peroxomolybdenum precursor solution ［29］was prepared by dissolving different contents of molyb⁃denum trioxide into 10.0mL of 30%hydrogen peroxide.The mixture solution was poured into dishes after 2h and then the dishes were heat treated at 40and 100℃for 8and 20h ，respectively ，forming the as -made com⁃posites consisting of Pluronic F127，phenolic resins ，and Mo species （denoted as as -made sample ）.Then ，the calcination of as -made sample was implemented in a tubular furnace under N 2atmosphere.The temperature program was set from 25℃to 350℃with a ramp of 1℃/min ，maintenance for 3h ，and then to 600℃with 1℃/min ，maintenance for 2h.The obtained sample after pyrolysis was named as ordered mesoporous carbon support ultrasmall molybdena nanoparticles （OMC -US -MoO 3-x ），wherein x represent the actual mass fraction of MoO 3.1.3Activity Test The selective oxidation reaction of cyclooctene was carried out in the round -bottom flask （50mL ）.In which ，40.0mmol of cyclooctene ，40.0mmol of 5.5mol/L TBHP in decane ，10mg of OMC -US -MoO 3-7cata⁃lyst （0.0048mmol/L of MoO 3），6.0g of 1，2-dichloroethane as solvent ，and 15.0mmol of chlorobenzene as internal standard.The reaction temperature is 80℃.At different time intervals ，conversion was calculated by sampling.The samples were analyzed on an Agilent 7890A gas chromatograph equipped with a HP -5column and products were confirmed by GC -MS.TOF values （mol of reacted cyclooctene per mol of catalyst and hour ）was calculated at about half conversion of the reaction.The catalyst was reused after washing by water and drying.The test condition was kept same to the first time on the cyclic test.2Results and Discussion2.1Synthesis and CharacterizaitonThe developed in situ confinement growth strategy is employed to the preparation of ordered mesoporous carbon support ultrasmall molybdena nanoparticles （OMC -US -MoO 3）composites （Fig.1）.In the synthesis sys⁃tem ，Pluronic F127is used as the structure -directing agent （soft -template ），preformed phenolic resins is used as carbon resource ，peroxomolybdenum solution is used as precursor ，and ethanol/H 2O is used as co -solvent ，respectively.The as -made sample and product OMC -US -MoO 3composites can be obtained after heat -treatment at 100and 600℃，respectively.The mass content of MoO 3in the OMC -US -MoO 3composites can be well tuned through adjusting the amount of peroxomolybdenum precursor in the synthesis system.TGA curves （Fig.2）show that the mass fractions of MoO 3species in the OMC -US -MoO 3composites areFig.1Illustration of the construction of OMC ⁃US ⁃MoO 3composites via the in situ confinementgrowth strategy Fig.2TGA curves of the OMC ⁃US ⁃MoO 3composites with different MoO 3contents obtained afterpyrolysis at 600℃,respectivelyMass fraction of MoO 3(%):a .4;b .7;c .10;d .16;e .27.1591Vol.42高等学校化学学报4%，7%，10%，16%and 27%（Table 1），respectively ，when adjusting the amount of molybdenum precursors in the synthesis system.The mass loss below 100℃is caused by the volatilization of adsorbed water in the composites.A slight mass increasement can be detected between 100and 300℃，demonstrating the existence of trace amount of MoO 2and abundant MoO 3in the composites.The mass increasement can be attributed to the oxidation of the trace amount MoO 2.Subsequently ，the huge mass loss above 300℃can be observed attribu -ting to the remove of carbon species in the composites.The mass loss between 100and 600℃is approximate to the mass fraction of MoO 3species in the composites.The SAXS patterns ［Fig.3（A ）］of OMC -US -MoO 3-4and OMC -US -MoO 3-7composites show two scatteringdiffraction peaks at 0.391and 0.782nm −1，and 0.412and 0.824nm ‒1，respectively ，indexing to the （100）and （200）reflections of a hexagonal mesosturtures with space group P 6mm .With the increasement of MoO 3content ，the q values of the （100）diffraction peaks shift to 0.532，0.617，and 0.678nm −1，for samples OMC -US -MoO 3-10，OMC -US -MoO 3-16，and OMC -US -MoO 3-27，respectively.The corresponding cell parame⁃ters of five composites are calculated to be about 18.5，17.6，13.6，11.7，and 10.7nm with the increased MoO 3content ，respectively.WAXRD patterns ［Fig.3（B ）］of five composites all show no diffraction peaks of MoO 3phase ，suggesting the ultrasmall particle size of MoO 3nanocrystals in the frameworks.This result demonstrates that the ordered mesoporous carbon frameworks can confine the size of MoO 3nanocrystals to an ultrasmall size even at a high MoO 3content effectively.Nitrogen adsorption -desorption isotherms of five OMC -US -MoO 3composites obtained after calcined at 600℃in N 2all display representative type -Ⅳcurves with H2hysteresis loops ［Fig.4（A ）］，in agreement with the previously reported ordered mesoporous materials ［30~32］.Sharp capillary condensation steps in the relative pressure （p /p 0）of 0.41―0.70are observed for five composites ，demonstrating the narrow pore size distribu⁃tion.The Brunauer -Emmett -Teller （BET ）surface area and pore volume of five composites are calculated and listed on Table 1.The surface area and pore volume decrease with the increased MoO 3content ，which can be attributed to the partial destroy and disappear of pore structures.The average pore sizes of five composites are also calculated and listed on Table 1from their pore size distribution curve ［Fig.4（B ）］derived from the adsorption branch based on BJH model.The average pore sizes are 4.7，5.7，5.5，5.4，and 4.6nm ，Table 1Structural and textural parameters for OMC -US -MoO 3with different content Sample No.12345MoO 3content （%，mass fraction ）47101627S BET /（m 2·g -1）796693652574428V /（cm 3·g -1）0.620.540.490.410.27D /nm 4.75.75.55.4 4.6Fig.3SAXS(A)and WA ⁃XRD(B)patterns of the OMC ⁃US ⁃MoO 3composites with differentMoO 3contents obtained after pyrolysis at 600℃Mass fraction of MoO 3(%):a .4;b .7;c.10;d .16;e .27.1592No.5王常耀等：原位限域生长策略制备有序介孔碳负载的超小MoO 3纳米颗粒respectively.According to the cell parameters results ，the pore walls of five composites are calculated to be 14.1，11.9，8.1，6.3，and 6.1nm ，respectively.SEM images （Fig.5）show that OMC -US -MoO 3-4and OMC -US -MoO 3-7composites own the most regular mesostructures.Notably ，the regular ［100］and ［110］directions can be clear observed from the SEM images of OMC -US -MoO 3-7composites ［Fig.5（B ）and （F ）］.In addition ，the mesopores are opened and no obvious big metal nanoparticles can be observed from the surface.With further increasement of MoO 3content ，the reg⁃ular mesostructures is partial destroyed.TEM images of OMC -US -MoO 3-7composites ［Fig.6（A ）—（C ）］taken along the ［100］and ［110］directions manifest a well -defined 2D hexagonal mesostructures in agreement with the result of the SAXS pattern ［Fig.2（A ）］.The lattice spacing is measured to be 0.35nm from the HRTEM image ［Fig.6（D ）］，attributing to the （040）crystalline planes of α-MoO 3［33］.The average size of MoO 3nano⁃crystals is estimated to be （4.1±1.0）nm from the size statistics diagram.The survey spectrum of the OMC -US -MoO 3-7composites shows the presence of only Mo ，O and C elements ［Fig.7（A ）］.The high -resolution Mo 3d core level XPS spectra ［Fig.7（B ）］show four peaks at 230.5，232.7，233.6，and 235.9eV ，demon⁃strating the co -existence of Mo 4+and Mo 6+species ［34~36］.The ratio of Mo 4+/Mo 6+is calculated to be about 13%.Only a few Mo 4+signals can be detected from the spectrum ，in agreement with the TGAresults.Fig.4N 2adsorption⁃desorption isotherms(A)and pore size distributions(B)of the OMC⁃US⁃MoO 3composites with different MoO 3contents obtained after pyrolysis at 600℃Mass fraction of MoO 3(%):a .4;b .7;c.10;d .16;e .27.Fig.5SEM images of OMC⁃US⁃MoO 3composites with different MoO 3contents obtained afterpyrolysis at 600℃Mass fraction of MoO 3(%):(A)4;(B)7;(C)10;(D)16;(E)27.1593Vol.42高等学校化学学报2.2Formation Mechanism Studies Based on the above results ，we propose that the in situ confinement growth strategy show significant impact on the formation of final OMC -US -MoO 3composites.The obtained MoO 3nanocrystals show ultrasmall particle size （<5nm ）and excellent dispersity on the mesoporous carbon frameworks.This structure can be retained even the mass fraction of MoO 3is increased to 27%.However ，the regular mesostructures can be partial destroyed with the increased MoO 3mass content.According to the results that no large MoO 3nanocrys⁃tals can be detected from samples obtained after pyrolysis at 600℃，the unregular mesostructures can be attributed to the uncontrollable origin co -assembly process.2.3Selective Oxidation of Cyclooctene The selective oxidation reaction of cyclooctene with high catalytic performance and stability is still highly desired.However ，the stability of active nanoparticles in catalytic reaction is a major challenge ，especially for active nanoparticles with ultra -small size.For our case ，the OMC -US -MoO 3-7composites show most regular mesostructures ，largest pore sizes ，appropriate hole wall size ，MoO 3content and dispersity.So ，the obtained OMC -US -MoO 3-7composites catalyst is selected as the catalyst for cyclooctene epoxidation.The reactions were carried out using 1，2-dichloroethane as solvent in flask with chlorobenzene as internal standard at 80℃.The OMC -US -MoO 3-7composites catalyst shows a high TOF value of 2163h ‒1which is calculated on the basis of the experimental data at 2h.Meanwhile ，a high conversion （100%）of cyclooctene ，and selectivity （>99%）to 1，2-epoxycyclooctane at 8h can also be parison with the reported heterogeneous Mo -based catalyst using similar conditions was shown in Table 2.The present OMC -US -MoO 3-7catalystshowsFig.7Survey XPS spectrum(A)and high⁃resolution XPS spectra of Mo 3d (B)for OMC⁃US⁃MoO 3⁃7composites obtained after pyrolysis at 600℃Fig.6TEM images of OMC⁃US⁃MoO 3⁃7composites obtained after pyrolysis at 600℃Viewed along the hexagonal （A ）and columnar （B ，C ）directions and HRTEM image （D ）of a representative MoO 3nanoparticle.1594No.5王常耀等：原位限域生长策略制备有序介孔碳负载的超小MoO 3纳米颗粒a higher TOF value than MoO 3/C ［8］，MoO 3/SiO 2［37］，Mo -MOFs ［9］，Mo -MCM -41［38］，Mo -SBA -15［38］，［Pipera⁃zinCH 2｛MoO 2（Salen ）｝］n ［39］，and MNP 30-Si -inic -Mo ［40］as previous reported.It should be noted that cyclooc⁃tene still gave about 18%conversion ［Fig.8（A ）］in the absence of catalyst owing to the presence of strong TBHP oxidants ，which is consistent with previous reports ［41，42］.Further ，two other substrates ，cyclohexene and styrene were also tested under the same conditions to test the versatility of OMC -US -MoO 3-7as an epoxida⁃tion catalyst.Surprisingly ，the conversion of cyclohexene to 1，2-epoxyclohexane can reach 54%in 8h.Inaddition ，the conversion of styrene to styrene oxide can reach 95%in 36h ，respectively （Fig.S1，see the Sup⁃porting Information of this paper ）.Beside the efficient conversion of catalyst and high TOF values ，the stability of catalyst is also very impor⁃tant ，especially for heterogeneous catalysis.Here ，the hot filtration test was used to assess the presence of active Mo species in solution.When the reaction lasted for 2h ，we removed the catalyst by hot filtration and let the mother liquid for reacting another 6h.The results showed that there was only a slight increase in con⁃version ［Fig.8（A ）］，which is proof of a heterogeneous catalysis.For the recycling study ，cyclooctene epoxida⁃tion was performed maintaining the same reaction conditions except using the recovered catalyst.It can be clearly found that obvious changes are undetected for catalytic performance after five runs ［Fig.8（B ）］.It indi⁃cates that ultrasmall MoO 3nanoparticles supported on ordered mesoporous carbon is highly stable and can be reused ，demonstrates its potential for industrial applications.The high conversion ，selectively ，and the TOF value for the cyclooctene epoxidation reaction can be attributed to the unique structure of the OMC -US -MoO 3-7composites.The high surface area ，volume ，andTable 2Calculating TOF value for epoxidation of cyclooctene and comparing with other catalysts *Catalyst OMC -US -MoO 3-7MoO 3/C MoO 3/SiO 2Mo -MOFs Mo -MCM -41Mo -SBA -15［PiperazinCH 2｛MoO 2（Salen ）｝］n MNP 30-Si -inic -MoTime/h 2267331224Conv.（%）5280909397999546Epoxide sel.（%）>9910010099959398100TOF/h -1216353［8］72［35］270［9］22［36］40［36］16［37］2［38］*.TOF values(mol of reacted cyclooctene per mol of catalyst and hour)were calculated at abouthalf conversion of the reaction.Fig.8Time course plots of cyclooctene epoxidation(A)and reusability(B)by using OMC⁃US⁃MoO 3⁃7com⁃posites as catalystReaction conditions ：40.0mmol of cyclooctene ，40.0mmol of 5.5mol/L TBHP in decane ，10mg of OMC -US -MoO 3-7catalyst （0.0048mmol/L of MoO 3），6.0g of 1，2-dichloroethane as solvent ，and 15.0mmol of chlorobenzene as internalstandard.The reaction temperature is 80℃.15951596Vol.42高等学校化学学报uniform mesopores can not only enrichment the reaction substrate but also in favor to the diffusion of sub⁃strates.The ultrasmall MoO3nanocrystals size and its excellent dispersity in the frameworks can expose more active sites.All these features are beneficial to the rapid conversion of substrate molecular with high selective⁃ly and conversion.3ConclusionsIn summary，an in situ confinement growth strategy was developed to the construction of ordered mesopo⁃rous carbon support ultrasmall molybdena nanoparticles（OMC-US-MoO3）composites.Ordered mesoporous carbon was used as an effective matrix to in situ confine the growth of MoO3nanocrystals.The obtained MoO3 nanocrystals show ultrasmall particle size（<5nm）and excellent dispersity on the mesoporous carbon frame⁃works.In addition，a serious of OMC-US-MoO3composite can be obtained with controllable specific surface areas（428―796m2/g），pore volumes（0.27―0.62cm3/g），MoO3contents（4%―27%，mass fraction）and uniform pore size（4.6―5.7nm）.The mesostructures can be retained even the MoO3content as high as27%. 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碳纳米管及其应用
1 引言纳米材料是纳米技术的基础，而碳纳米管又可称为纳米材料之王。
碳纳米材料在纳米材料技术开发中举足轻重，它将影响到国民经济的各个领域。
碳纳米管的发现是碳团簇领域的又一重大科研成果，本文探讨了碳纳米管的结构、特性、活化方法，评述了这种纳米尺寸的新型碳材料在电化学器件、氢气存储、场发射装置、碳纳米管场效应晶体管、催化剂载体、碳纳米管修饰电极领域的应用价值，展望了碳纳米管的介入对全球性物理、化学及材料等学科界所带来的美好前景。
在1991年日本NEC公司基础研究实验室的电子显微镜专家饭岛(Iijima)在高分辨透射电子显微镜下检验石墨电弧设备中产生的球状碳分子时，意外发现了由管状的同轴纳米管组成的碳分子,这就是现在被称作的“Carbon nanotube”，即碳纳米管,又名巴基管。
1993年。
S.Iijima等和DS。
Bethune等同时报道了采用电弧法，在石墨电极中添加一定的催化剂，可以得到仅仅具有一层管壁的碳纳米管，即单壁碳纳米管产物。
1997年，AC.Dillon等报道了单壁碳纳米管的中空管可储存和稳定氢分子，引起广泛的关注。
相关的实验研究和理论计算也相继展开。
初步结果表明：碳纳米管自身重量轻，具有中空的结构，可以作为储存氢气的优良容器，储存的氢气密度甚至比液态或固态氢气的密度还高。
适当加热，氢气就可以慢慢释放出来。
研究人员正在试图用碳纳米管制作轻便的可携带式的储氢容器。
据推测，单壁碳纳米管的储氢量可达10%（质量比）。
此外，碳纳米管还可以用来储存甲烷等其他气体。
利用碳纳米管的性质可以制作出很多性能优异的复合材料。
例如用碳纳米管材料增强的塑料力学性能优良、导电性好、耐腐蚀、屏蔽无线电波。
使用水泥做基体的碳纳米管复合材料耐冲击性好、防静电、耐磨损、稳定性高，不易对环境造成影响。
碳纳米管增强陶瓷复合材料强度高，抗冲击性能好。
碳纳米管上由于存在五元环的缺陷，增强了反应活性，在高温和其他物质存在的条件下，碳纳米管容易在端面处打开，形成一个管子，极易被金属浸润、和金属形成金属基复合材料。
第六章 纳米孔材料
例②：KMnO4+马来酸→介孔MnO2(孔径0.7~6nm，比表面积297m2/g)
• 特点：反应过程易控制、设备简单、成本低；介孔固体 纯度高、均匀性好、易于掺杂等优点
(2) 模板合成法 (一) 表面活性剂模板法
• 原理过程：
（1）将表面活性剂加入到溶剂中，形成胶束； （2）然后加入无机物种、酸或碱，搅拌使之反应完全，得到比较柔顺、 松散的表面活性剂和无机物种的复合产物； （3）再通过水热处理、室温陈化等处理提高无机物种的缩聚程度，形 成稳定的中间产物； （4）然后洗涤、干燥，得到有机-无机复合前驱体； （5）再通过灼烧或溶剂萃取去除其中的表面活性剂，便得到介孔材料。
从(介)孔材料形状分：
纳米(介)孔颗粒 纳米(介)孔膜 纳米(介)孔块体(介孔固体)
6.1 定义及分类
从孔结构分
(a) 六方相介孔材料；(b)立方相介孔材料；(c)层状介孔材料 MCM 48 MCM 50 MCM 41 SBA-15 MCM 41 （六方相介孔分子筛）：
发明：1992年，J. S. Beck et al., J. Am. Chem. Soc. 114, 10834 (1992). 结构导向剂(structure-directing agent)：十六烷基三甲基铵盐 结构特点：孔径1.5-10nm，壁厚1-1.5nm，热稳定性差
(2) 模板合成法
(2) 阴离子表面活性剂
Anionic surfactant templated mesoporous silicas (AMS) 助结构导向剂 (co-structure directing agent)
相互作用
最早报道： Che S, Garcia-Bennett AE, Yokoi T, et al, Nature Materials, 2003, 2: 801-805
介孔二氧化硅负载碳点的方法
介孔二氧化硅负载碳点的方法1.引言1.1 概述概述:介孔二氧化硅负载碳点的方法是一种将碳点纳入介孔二氧化硅结构中的制备技术。
碳点作为一种新型纳米材料，具有很多优异的物理和化学性质，如较小的尺寸、可调控的荧光发射、良好的生物相容性等。
同时，介孔二氧化硅作为一种具有高比表面积和可调控孔径特性的纳米材料，被广泛应用于催化、吸附、分离等领域。
将碳点负载到介孔二氧化硅中，可以充分利用两种材料的优势，实现二者性能的协同提升。
在制备过程中，常用的方法包括溶胶-凝胶法、共沉淀法、热解法等。
这些方法不仅可以控制介孔二氧化硅的孔径和孔容，还能通过调节碳点的加载量和分散性，实现对复合材料结构和性能的调控。
介孔二氧化硅负载碳点的方法具有很多优势。
首先，通过这种方法可以获得具有大比表面积和高孔容的复合材料，有利于增强其吸附、催化等性能。
其次，通过调节碳点的特性和负载量，可以实现对复合材料的量子效应和荧光发射的调控，具有潜在的光电器件和生物标记的应用价值。
此外，界面效应和相互作用使得复合材料拥有更加复杂的性质和功能，有助于拓展其在催化、传感、能源储存等领域的广泛应用。
综上所述，介孔二氧化硅负载碳点的方法为制备具有高性能和多功能的纳米复合材料提供了一种有效途径。
随着对这种方法的深入研究和优化，相信将会有更多的应用领域受益于这种新型材料结构的发展和应用。
1.2文章结构文章结构本文主要分为引言、正文和结论三个部分。
引言部分主要对课题进行概述，介绍了介孔二氧化硅负载碳点的研究背景和意义。
同时，介绍了文章的结构，简要概括了各章节的内容和安排。
引言部分将引导读者进入整篇文章的主题，并为正文部分提供了一个清晰的背景和前提。
接下来是正文部分，其中包括了介孔二氧化硅的制备方法和碳点的制备方法。
在介孔二氧化硅的制备方法中，将介绍相关的化学合成方法和物理制备方法，并探讨各种方法的优缺点。
在碳点的制备方法中，将介绍碳点的来源以及制备过程中的关键参数和条件，并探讨不同制备方法对碳点性质的影响。
介孔材料2014
5. 材料的形貌不同。沸石分子筛是完美的无机晶体材料，因此 它的形体（一般是指单晶的形貌）与其结构密切相关。尽管最 近有人可以制备出单一分布的类似光子晶体一样的Silicalite-1晶 体材料， 但是沸石分子筛的外貌相对变化有限，控制较难。介 孔材料晶体的形貌相对沸石要好控制的多。
1.1 软模板法”合成介孔分子筛的技术问题
（3）加入有机膨胀剂。它是增加介孔孔径的一个有效的方法。 疏水的有机物种可以溶解在表面活性剂胶束疏水区域内，导致 胶束膨胀，从而增大所得介孔材料的孔径。这种膨胀作用与其 溶解度有关。添加有机烷烃如十二烷，TMB，三丙基苯和聚丙 二醇等可有效扩大孔径。例如用嵌段共聚物为模板剂在酸性条 件下合成介孔氧化硅材料时，添入TMB后，孔径可以扩至40 nm。但值得注意的是，一般加入TMB后，介孔材料的有序性 大大降低。
SBA-15的透射电镜照片 SBA-16（上）和介孔 氧化钛（下）薄膜的 HRSEM像
1.1.1 水热合成：
介孔分子筛一般是通过溶液化学反应制备的，类似于沸石分子 筛的“水热”合成。制备过程经历了典型的“溶胶-凝胶”过程。 通常介孔材料的合成温度较低（室温至 100 ℃）。介孔材料的 一般合成程序为： ①先将表面活性剂等模板剂溶解在水中，得到均匀的溶液； ②加入无机原料进行溶液化学反应得到溶胶或凝胶； ③进行“水热”处理反应、晶化； ④冷却至室温后，过滤、洗涤，干燥； ⑤焙烧或萃取，除去表面活性剂等有机模板剂，得到介孔分子 筛材料。
2.2 电子显微分析
电子显微镜分析已经成为在介孔分子筛研究领域中最强有力 的结构分析方法之一，这一点已经成为共识。电子显微镜常 被用来研究介孔材料空间结构、周期性、孔道形貌、材料粒 子外貌等。新一代的分析型高分辨电镜还能给出固态材料中 的超结构、晶体微区结构和化学组分、缺陷、微晶、共生等 晶体精细结构信息。这些信息往往很难从其他实验手段获得。