碳球/有序介孔碳复合涂层的制备及其防护性能

以可溶性酚醛树脂为碳前驱体,三嵌段共聚物F127为模板剂,碳球为填充相,经旋涂及溶剂蒸发诱导自组装,在不锈钢基体上构筑了具有高疏水性的碳球/有序介孔碳微纳米复合涂层.进一步利用PT-FE进行表面氯化修饰,获得了超疏水性能,润湿角达142°.扫描电子显微镜显示该复合涂层具有微米级褶皱/纳米级介孔孔道的复合结构.在模拟的海...     

甘氨酸衍生的双介孔掺氮有序介孔炭用于超级电容器和氧气还原

掺氮多孔炭材料在电化学能量储存和转化方面具有良好的应用前景.可控的氮原子掺杂与孔结构设计对提高其性能起着重要作用.本工作利用无溶剂纳米铸造法,以甘氨酸(Gly)为单一前驱体、以SBA-15为硬模板,制备了掺氮有序介孔炭材料(N-OMCs).甘氨酸在SBA-15孔道内的限域热解对提高碳产率、氮掺杂量以及构筑双介孔结构非常...     

有序介孔SnO_2的制备及其气敏特性的研究

以SBA-15为硬模板,利用浸渍法将SnCl2担载到介孔孔道中,通过控制反应温度和反应环境合成SnO2/SBA-15复合材料,用NaOH溶液除去SBA-15模板,制备具有与SBA-15反转结构的介孔SnO2;通过XRD,TEM和N2吸脱附的表征,证明所制备的SnO2具有有序的介孔结构和较大的比表面积;对乙醇敏感特性进行了初步探讨。     

pH值敏感介孔纳米复合材料SBA-15/PAA的制备与性能研究

通过浸渍吸附的方法将pH值敏感的功能单体-丙烯酸引入到介孔二氧化硅SBA-15的孔道内,经自由基聚合使丙烯酸(AA)在孔道内聚合,成功合成了pH值敏感的SBA-15/聚丙烯酸(PAA)纳米复合材料,所得纳米复合材料的结构通过XRD、TEM、氮气吸附/脱附、TG、FT-IR等手段进行了表征,并进行了pH敏感性能研究.结果表明,当聚合物(PAA)的量达到20%左右时,复合材料仍然具有较大的孔体积0.5203cm3/g和较高的比表面积334.5m2/g.聚合反应的发生没有破坏SBA-15的有序介孔结构,这种纳米复合材料初步显示出了pH敏感性.这种具有高比表面的pH值响应介孔纳米复合材料,有望在药物缓释领域得到应用.     

多孔硅/碳复合负极材料的制备及电化学性能

以介孔二氧化硅SBA-15为硅源, 采用镁热还原法和化学气相沉积(CVD)法合成了具有莲藕状结构的多孔硅/碳复合材料。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和氮气吸脱附法研究了原料配比, 混压方式以及反应温度对多孔硅物相组成和结构形貌的影响。多孔硅的最佳合成条件为: 镁粉过量20wt%, 原料经球磨混合均匀后直接在750℃下高温反应4 h。对多孔硅及多孔硅/碳材料进行了电化学性能测试, 在0.5 A/g电流密度下循环70次后仍保持1633.1 mAh/g的可逆容量, 并且在8 A/g下容量达到580.1 mAh/g, 表现出优异的循环稳定性以及倍率性能。     

纳米颗粒磁增强SBA-15介孔复合材料的制备及磁性能

利用浸渍法合成了Co₃O₄/SBA-15和CoFe₂O₄/SBA-15介孔纳米磁性材料, 并利用X射线粉末衍射(XRD)、 透射电子显微镜(TEM)、 场发射扫描电子显微镜(FESEM)及振动样品磁强计(VSM)对样品的微观结构和磁性能进行了分析。结果显示, Co₃O₄及CoFe₂O₄纳米颗粒分布在SBA-15介孔材料的孔道中, 可有效提高SBA-15介孔材料的磁性能。研究发现, SBA-15介孔纳米磁性材料的磁特性由掺杂的纳米磁性颗粒的性质决定, 其磁性能随Co₃O₄及CoFe₂O₄含量的增加而升高, 矫顽力可达400Oe, 饱和磁化强度达9emu/g。      

短通道介孔二氧化硅的制备与水蒸气吸附性能EI北大核心CSCD

在高速搅拌条件下调整分子组装过程的外界应力,制备出短通道(500~700 nm)、条棒状的有序介孔二氧化硅,研究不同模板剂脱除方式对介孔二氧化硅的水蒸气吸附性能影响,获得强化介孔二氧化硅吸附性能的方法。结果表明:在短通道、条棒状介孔二氧化硅的制备过程中模板剂脱除的温度对材料表面羟基浓度影响较大,选择萃取与低温煅烧相结合方法脱除模板剂,萃取4次,250℃煅烧脱除模板剂的材料水蒸气吸附性能最好,在实验条件下平衡吸附时间约为7.5 min,是商品SBA-15的78.95%;平衡吸附量0.73 g·g^(-1),是商品SBA-15的1.49倍。     

纳米浇注法制备有序介孔WC/C复合材料及电催化性能

以介孔SiO2为硬模板,通过纳米浇注法在模板孔道中引入不同质量配比的碳源和钨源前驱物,经过高温碳化还原反应,刻蚀除去模板后得到了介观结构有序的SBA-15和KIT-6介孔碳化钨/炭(WC/C)复合材料。采用XRD、TEM、EDX、TGA、CV和N2吸附-脱附等测试手段,对所得复合材料进行了物化性质分析和结构表征。结果表明,该介孔WC/C复合材料具有有序的介观结构(p6mm,Ia3d)、高的比表面积(约500m2/g)和较大的孔径(约4nm)。CV测试表明,三维贯通的有序TC/C-KIT-6为载体负载Pt催化剂,对甲醇的催化氧化具有更优异的作用。     

工艺条件对碳化稻壳镁热还原产物组成的影响

以同时含有碳源和硅源的稻壳制备碳化稻壳,采用镁热法还原其中的SiO2,借助XRD对还原产物进行分析,探讨了镁热还原工艺对产物组成的影响。结果表明:碳化稻壳中的SiO2在490℃可以发生镁热还原反应,当还原温度低于700℃时,还原产物是Si或Mg2Si;当还原温度超过700℃时,还原产物中形成SiC;当还原温度高于800℃时,产物中有Mg2SiO4生成。镁热还原温度在600~700℃之间时,通过控制Mg与碳化稻壳中的SiO2的质量配比,可以制备出Si/C复合材料。     

基于有序介孔碳/PDDA固定化漆酶的邻苯二酚传感器性能研究

采用有机交联水性环氧树脂为碳源,以SBA-15为模板,制备了有序介孔碳(OMC),并对其电化学性能进行研究。透射电镜结果表明其具有典型的二维有序六角介孔结构,孔径大约为3nm。电化学测试结果表明OMC/Lac/Au电极对邻苯二酚具有很好的电催化氧化活性。将OMC应用于构建漆酶生物传感器,结果表明,传感器对邻苯二酚的线性检测范围为0.67~8.59μmol/L,灵敏度为0.349A/(mol/L),检测限为0.117μmol/L。     

盐酸小檗碱/介孔二氧化硅载体的制备与缓释行为研究

采用水热合成法制备了SBA-15和SBA-16两种介孔SiO₂载体材料,利用浸渍法将盐酸小檗碱(BBH)原料药负载于载体上,制备了载药BBH/SBA-15和BBH/SBA-16。通过多种表征方法对载药后材料的晶体结构、孔道结构等进行了测试,并研究了材料的载药、释药规律。结果表明,SBA-15和SBA-16的载药量分别为13.50%和3.45%。与BBH原料药相比,两种介孔SiO₂载体均能够延长药物的释放,具有缓释效果。但SBA-15的孔径(5.77nm)较大,释药存在突释现象;而SBA-16的孔径(3.95nm)较小,能够缓慢释放药物。     

Effect of N2O/SiH4 ratio on the properties of low-temperature silicon oxide films from remote plasma chemical vapour deposition

Silicon oxide films have been deposited with remote plasma chemical vapour deposition (RPCVD) at low temperatures (<300 °C) from SiH₄---N₂O. The effect of a gas-phase reaction on the SiO₂ film properties and Si/SiO₂ interface was investigated. As the partial pressure ratio was increased above N₂O/SiH₄ = 4, a gas-phase reaction with powder formation was observed, which degraded film properties, increased surface roughness, and decreased deposition rate. When N₂O/SiH₄ <4, there was no detectable IR absorption in the film associated with hydrogen-related bonds (Si---OH and Si---H) but when N₂O/SiH₄ >4, the incorporation of Si---OH bond became significant and Si¹⁺, intermediate state silicon at the interface, was more abundant. The oxide fixed charge, interface trap density, surface roughness and leakage current were increased when there was powder formation in the gas phase. High plasma power also favoured the powder formation in the gas phase. C---V and I---V characteristics were measured and it was shown that these electrical properties were directly related to the process condition and material properties of the oxide and the Si/SiO₂ interface.     

介孔Fe-SiO2复合材料的制备及吸附协同催化性能

采用原位一步合成法,在含有模板剂、AlCl₃和H₂O的弱酸性反应体系中,引入Si源和Fe源,通过原位共沉积的方式,成功制备出Fe修饰的介孔SiO₂（Fe-SiO₂）复合材料。采用XRD、N₂吸附、FTIR、UV-vis、SEM和EDS等手段表征了介孔Fe-SiO₂复合材料样品的结构、形貌和化学组成;将所获得的介孔Fe-SiO₂复合材料用于吸附和协同催化去除水体中有机污染物亚甲基蓝（MB）;考察了Fe源添加量对介孔Fe-SiO₂复合材料结构和性能的影响。研究结果表明:合成体系中rFe:Si ≤ 0.05（摩尔比）时,所得Fe-SiO₂介孔材料保留了介孔孔道的高度有序性和大比表面积（860~889 m2·g-1）,Fe在介孔Fe-SiO₂复合材料中主要以四配位骨架掺杂的形式存在;当rFe:Si=0.1时,其比表面积下降为526 m2·g-1,Fe以骨架内和骨架外氧化物的形式共存于介孔Fe-SiO₂复合材料中。所有介孔Fe-SiO₂复合材料在去除MB的实验中均表现出很大的吸附容量和优良的多相类芬顿催化能力。其中,rFe:Si=0.05时所获得的介孔Fe-SiO₂复合材料样品性能最佳,对高浓度MB（250 mg·L-1）的吸附和催化总量达到213 mgg-1。      

Low temperature plasma-assisted oxidation and thin-film deposition processes for forming device-quality SiO2/Si and composite dielectric-SiO2/Si heterostructures

In the high-temperature thermal oxidation of Si, the SiO₂/Si interface is continuously regenerated as the bulk oxide grows. This paper describes an alternative low temperature, 200–300 °C, plasma-assisted process that optimizes electrical properties of SiO₂/Si interfaces and bulk SiO₂ layers by separately controlling interface formation and bulk oxide deposition. Composite dielectrics, oxide/nitride (ON) and oxide (ONO), have been fabricated by extending the low temperature plasma-assisted processes to include deposition of Si₃N₄ films. The electrical properties of SiO₂/Si structures formed by the two-step, low temperature oxidation-deposition process are essentially the same as those of SiO₂/Si structures formed by high temperature, 850–1050 °C, thermal oxidation. The electrical properties of devices incorporating ON and ONO composite dielectrics are degraded with respect to the SiO₂/Si structures, but are similar to those of composite dielectrics formed by combinations of high temperature processing.     

Segregation of Cu in Cu (Ti) alloys during nitridation in NH3

Cu(Ti 27 at.%) alloys on SiO₂ were reacted in NH₃ for 30 min over the temperature range 400–700 °C. Rutherford backscattering spectrometry in conjunction with high resolution transmission electron microscopy were utilized to investigate reaction products. At 400–450 °C, Ti is observed to segregate to the free surface to react with NH₃, forming an Ti oxynitride layer. Above 500 °C, Ti segregates to both the free surface and to the alloy/SiO₂ interface, leaving relatively-pure Cu layer. Reaction between Ti and SiO₂ results in a TiO/Ti₅Si₃ bilayer structure. By use of high spatial resolution energy dispersive X-ray spcctroscopy, the presence of a Cu-containing layer at the TiO/Ti₅Si₃ interface is observed. This layer may also contain Ti, Si and/or O. We propose a mechanism for Cu segregation to this interface which requires Cu diffusion across TiO and subsequent dissociation of Ti₅Si₃. Thermodynamic calculations support this mechanism.     

Structural, chemical, and electrical characterisation of reactively sputtered WSx thin films

WS_x films were sputter-deposited on Si, SiO₂/Si, and glass substrates from a WS₂ target in an Ar/H₂S atmosphere. Their structure, morphology, chemical composition, and electrical properties were investigated as a function of deposition parameters such as working pressure and H₂S fraction. Films could be grown in the composition range WS_0.3−WS_3.5. Crystallisation was achieved at substrate temperatures T_s > 70 °C and compositions 0.7 ≤ x ≤ 1.95. While the first 5–50 nm near the interface exhibited a basal orientation (c), further growth resulted in the formation of edge-oriented platelets (c) giving rise to a porous, lamellar microstructure. The crystalline structure was mainly turbostratic, while some degree of ordered stacking was present in samples grown at high substrate temperature (600 °C). Resistivity measurements showed a semiconductor-type temperature dependence characterised by activation energies up to 95 meV. Sheet resistance was found to be nearly independent of film thickness, suggesting that the main carrier transport takes place in an interfacial layer of about 20 nm in thickness.     

Measurement of the current transient in Ta2O5 films

Current vs. time (I−t) measurements were performed on Ta₂O₅-based devices. Charge build-up at the Ta₂O₅/SiO₂ interface was used to explain the transient. The interfacial charge density was calculated from the I−t curve and the maximum was found to be 398 nC cm^-2 and 317 nC cm^-2 for Al/Ta₂O₅/Si and Al/Ta₂O₅/SiO₂/Si capacitors respectively. The value for MTOS was comparable with the value obtained by quasi-static measurements.     

高氮含量的有序氮氧化物介孔材料的研究

通过使用氨气作氮源,氮化介孔氧化硅和含铝氧化硅(SBA-15和Al-MCM-41)的前驱体(含模板剂),成功制备出高氮含量的有序氮氧化物介孔材料。主要氮化条件为:1273～1323K,8～24h.采用 CNH元素分析、红外光谱、Si固体核磁共振谱(MASNMR)、N₂吸附-脱附分析、小角XRD和高分辨透射电镜(HRTEM)进行表征,分析结果表明经过高温长时间氮化制备出的高氮含量(～21wt％)的氮氧化硅和含铝氮氧化硅介孔材料仍然具有高达700～900m²g^-1的比表面积、窄的孔径分布和良好的有序性.     

Electrochemical deposition of PbSe and CdTe nanoparticles onto p-Si(100) wafers and into nanopores in SiO2/Si(100) structure

Electrochemical deposition of PbSe and CdTe nanoparticles onto p-Si(100) wafers and into nanopores in SiO₂ layer grown thermally on p-Si(100) substrates (SiO₂/Si(100) structure) under illumination was studied. To produce nanopores we used SiO₂ layer with tracks developed by irradiation of 350 MeV Au ions. Pores structure was formed by chemical etching of the irradiated SiO₂ layer in dilute HF. The pores were shaped like truncated cones with a base diameter of 200 and 250 nm and height of 200 nm. Photoelectrochemical deposition of PbSe and CdTe was carried out with constant cathodic potentials from the water solutions containing Pb²⁺, Cd²⁺ cations and H₂SeO₃, H₂TeO₃ acids. The potentials applied were more positive than the equilibrium E_{Meⁿ⁺/Me⁰} redox potential. The underpotential deposition of Pb (or Cd) occurs only onto the co-deposited Se (or Te) atoms due to electrons photogenerated in Si substrate. The average sizes of PbSe and CdTe particles electrodeposited onto Si(100) wafers were dependent on the duration of electrodeposition, changing from 50 to 200 nm for PbSe and 30–80 nm for CdTe. According to XRD data, PbSe particles formed at ambient conditions had the crystalline structure. To deposit CdTe nanoparticles we used an electrolyte heated up to 80 °C. Variations in the electrodeposition time enabled one to form either separate chalcogenide particles or a polycrystalline film-like layer in case of electrodeposition onto p-Si(100) wafers and to control the degree of pore filling in case of electrodeposition into the nanopores of SiO₂/Si(100) structure.     

Structure and electrical properties of boron-added (Ba,Sr)TiO3 thin films fabricated by the sol-gel method

Thin films of Ba_xSr_1−xTiO₃ (BST, with x=0.5) were fabricated on a RuO₂/Ru/SiO₂/Si substrate by the spin coating of the multicomponent sol prepared using metal alkoxides. Boron alkoxide was intentionally introduced to establish a better microstructure and to reduce the leakage current. AFM indicated that a crack-free uniform microstructure having a smooth surface was gradually developed with increasing boron content. The relative dielectric permittivity of the 250-nm thick BST thin films fired at 700°C decreased with increasing content of boron, from 420 for the undoped film to 190 for the 10 mol% boron-added film at 1 MHz. This observation was interpreted in terms of a serial capacitance composed of the perovskite BST grain and the interfacial B₂O₃ glassy phase having a low dielectric permittivity. The leakage current density (J) also decreased with the amount of boron added. The leakage current for the applied voltage greater than 1 V showed a linear variation of logJ with E^1/2 at room temperature, suggesting that the interface-controlled Schottky emission was the dominant conduction process for the BST thin films fabricated on the RuO₂ electrode.