原位聚合法制备聚苯胺改性MoS2及其环氧复合涂层的防腐性能

为提高环氧涂料的防腐性能,本文引入MoS₂纳米片作为阻隔剂,并在MoS₂纳米片表面原位聚合聚苯胺(PANI),制备了夹层结构i-PANI@MoS₂纳米片,利用PANI提高涂层的导电性,达到阳极钝化的效果。研究发现,当PANI与MoS₂的摩尔配比增大到7∶1时,MoS₂片层表面被PANI均匀覆盖,改性效果最好。与环氧树脂复合后,i-PANI@MoS₂-7纳米片在环氧树脂中均匀分散,复合涂层导电率提高,PANI与MoS₂起到了协同防腐作用,此时i-PANI@MoS₂纳米片既作为涂层中的阻隔剂,又作为电化学腐蚀保护剂,因此复合涂层具有最大的阻抗值、最大腐蚀电压以及最小的腐蚀电流密度,防腐性能优异。但PANI与MoS₂配比进一步增大,MoS₂纳米片表面的聚苯胺会发生团聚,导致复合涂层的防腐性能下降。     

过硫酸氢盐催化材料(Co3O4/ACF)的制备及应用

通过改变溶剂热法和水热法中材料的配比和温度制备了18种四氧化三钴/活性炭纤维(Co₃O₄/ACF)复合材料,并将这些复合材料用于催化过一硫酸盐(PMS)降解染料橙黄Ⅱ。考察了制备材料的配比(Co²⁺和ACF)和温度对制得的Co₃O₄/ACF复合材料催化降解橙黄Ⅱ效率的影响,并采用X射线衍射仪、扫描电镜等对复合材料的元素组成和形貌进行了表征。结果表明:水热法制得的复合材料催化性能好,3 min内可完全降解100 mg/L橙黄Ⅱ。从表征结果可见,水热法能更有效地使Co₃O₄颗粒以纳米尺寸分散负载在ACF上。材料的配比对产品的催化降解效率无显著影响,温度对水热法制得的产品的催化降解效率影响不大。水热法在320 ℃条件下煅烧制得的复合材料催化性能好且ACF能基本保持结构完整,Co负载量约为17.2 mg/g。水热法制备的Co₃O₄/ACF复合材料循环利用性能优于溶剂热法制得的材料,在循环使用四次后,28 min内橙黄Ⅱ降解效率仍能达到99%。其高效降解与Co₃O₄/ACF和溶解态Co²⁺的催化作用均有关。正交试验表明,降解过程中时间对降解效果的影响最大,其次是PMS的浓度,催化材料的加入量对降解效率无明显影响。因此,在复合材料应用中,应保证充足的降解时间,并适当提高PMS的浓度。     

载银g-C3N4(Ⅰ)/g-C3N4(Ⅱ)同素异质结催化剂的制备及光催化固氮产氨性能

Ag作为助催化剂能够促进光电子的迁移,在光催化分解水制氢气、CO₂还原、重金属离子还原等反应中应用颇多,然而,到目前为止未见将Ag单质作为助催化剂用于光催化固氮产氨反应的报道。本工作制备了负载单质Ag的g-C₃N₄(Ⅰ)/g-C₃N₄(Ⅱ)同素异质结催化剂,并考察了其光催化固氮产氨的性能。采用X射线衍射(XRD)、透射电镜(TEM)、紫外可见光谱(UV-Vis)、X射线光电子能谱(XPS)、拉曼光谱(Raman)、荧光光谱(PL)、电化学阻抗谱(EIS)、光电流分析等手段对制备的催化剂进行了表征。结果表明,Ag以单质态存在于催化剂表面。所担载的Ag的等离子体效应一方面促进了催化剂对可见光的吸收,使反应体系能产生更多的光生电子-空穴对;另一方面使得光生电子能够在g-C₃N₄与Ag单质间迁移,提高了催化剂的电子-空穴分离效率。负载Ag后g-C₃N₄(Ⅰ)/g-C₃N₄(Ⅱ)同素异质结催化剂的铵离子产生速率为1.36 mg·L-1·h-1·g-1_cat,相比未负载Ag时(0.59 mg·L-1·h-1·g-1_cat)大幅提高,与Pt负载催化剂相当,并且是由单纯三聚氰胺和尿素制备的g-C₃N₄的4.9倍和3.4倍。除固氮反应外,制备的载银g-C₃N₄(Ⅰ)/g-C₃N₄(Ⅱ)同素异质结催化剂在光催化还原氧气制取双氧水的反应中也表现出优良的催化性能。     

TiO2负载锶铁氧体磁性材料光催化性能及表征

采用溶胶-凝胶法合成了TiO₂负载锶铁氧体光催化剂, 通过XRD、TEM、UV-Vis、VSM等方法对催化剂结构进行了表征, 并以高压汞灯为光源, 亚甲基兰为目标降解物, 对其光催化活性进行了研究. 结果表明, TiO₂负载锶铁氧体为复合型光催化剂, 负载后的复合光催化剂保持了良好的磁性能; 锶铁氧体的负载拓宽了催化剂的光响应区域, 光吸收带进入可见光区; 在负载量为20％, 催化剂用量1.5g/L条件下, 催化降解亚甲基兰的效率可达99.1％.     

碳纤维和二硫化钼混杂增强尼龙复合材料的摩擦学性能研究

以注塑成型法制备MoS₂和碳纤维混杂增强尼龙1010复合材料,采用MM-200型磨损试验机考察复合材料摩擦磨损性能。研究结果表明:在干摩擦条件下,MoS₂和碳纤维混杂可显著改善尼龙复合材料摩擦学性能,较小载荷下复合材料磨损以轻微磨粒磨损和疲劳磨损为主,较高载荷下复合材料则以热疲劳断裂剥落磨损为主。摩擦过程中MoS₂和对偶铁发生摩擦化学反应,生成和对偶底材具有较强结合能力的硫化亚铁和硫酸铁等,同时部分被氧化生成MoO₃。     

Ag掺杂优化g-C3N4结构及提升可见光降解性能的研究

石墨相氮化碳的改性已经成为光催化领域,特别是光催化材料领域的研究热点。本文以硝酸银和尿素为原料制备一系列不同Ag含量的Ag/g-C₃N₄光催化剂,并以罗丹明B水溶液模拟废水,在可见光下考察Ag/g-C₃N₄催化剂的光催化降解性能,最终获取最佳Ag掺杂量。通过XRD、SEM、FTIR、UV-Vis、PL等对光催化剂进行分析,发现Ag的掺杂有助于g-C₃N₄的剥离,改变了g-C₃N₄的电子结构,降低了其带隙能,使其在可见光区的吸收增强,抑制了光生电子-空穴对的复合。研究表明,当Ag掺杂量为2%时,Ag/g-C₃N₄光催化剂的效果最佳,300 min内降解率高达95.8%。     

TiO2/PEN表面改性对柔性DSSC性能的影响

对于柔性DSSC的透明光阳极而言,在低温下制备出结晶性高、颗粒间结合性能良好的TiO₂薄膜是其获得优异光电性能的关键。本文通过对比三种不同浆料添加剂(盐酸、乙二醇乙醚、小颗粒凝胶)对DSSC光电性能的影响,发现小颗粒凝胶的加入可以显著提高器件的光电性能。在此基础上,优化了小颗粒凝胶添加量及退火工艺,得出了最佳制备工艺条件,最终获得短路电流密度为8.14 mA/cm²、填充因子为67.9%、光电转化效率为4.1%的DSSC。进一步研究表明,小颗粒凝胶的加入一方面可以增强TiO₂颗粒之间的连接,从而提高TiO₂的成膜质量;另一方面可以增加TiO₂薄膜对光的散射,从而提高电池的吸光率。     

HKUST-1/KCoFC复合材料的制备及其对Cs+的吸附研究

在这项工作中,制备了一种以金属有机配位聚合物(MOFs)材料(HKUST-1)为载体,通过KCoFC(Co(NO₃)₂与K₄Fe(CN)₆反应产物)功能化修饰后的新型复合材料,并通过FTIR、SEM、XRD对其进行表征。研究初始Cs⁺浓度、吸附时间、溶液pH值对吸附效果的影响,用吸附动力学和吸附等温线模型研究HKUST-1/KCoFC对Cs⁺的吸附过程。实验表明:在40 min内,Cs⁺吸附量迅速增加,复合材料对Cs⁺吸附量最佳的pH为8;HKUST-1/KCoFC对Cs⁺吸附过程符合准二级动力学和Langmuir模型。     

磁性活性碳负载F掺杂纳米二氧化钛的光催化性质研究

通过溶胶-凝胶法制备F掺杂纳米TiO₂ (F-TiO₂), 将其负载到磁性活性碳(MAC)上, 制得易回收分离的高效催化剂(F-TMAC)。通过XRD、SEM、UV-Vis、XPS、VSM对样品进行表征。以合成样品为催化剂降解模拟废水活性染料艳红(X-3B), 结果表明该负载型催化剂在紫外光和可见光照射下光催化效果均优于P25催化剂。0.2 g负载型催化剂分别在紫外光和可见光照射下降解200 mL浓度为100 mg/L的X-3B溶液, 90 min后经18?W紫外光照射X-3B去除率达到99.8%; 250 W可见光照射X-3B去除率为83.1%。溶液中的复合催化剂可以用磁铁很容易分离, 具有优良的重复利用性能。经5次重复试验, 复合催化剂F-TMAC对X-3B的降解率仅下降了约6.0%。     

氧化石墨烯/H2O2可见光催化性能影响因素

为了研究氧化石墨烯/H₂O₂可见光催化处理含难降解有机物废水影响因素,用改进的Hummers法制备了氧化石墨烯(GO),通过扫描电镜(SEM)、电子能谱(EDS)、拉曼光谱对GO的微观形貌、成分及结构进行了表征.以甲基橙(MO)为难降解有机物代表,通过改变光照、pH值以及GO的量探究了不同条件对GO/H₂O₂复合试剂降解甲基橙的光催化效果.研究表明：GO/H₂O₂复合试剂可以通过光催化产生羟基自由基降解污染物,通过改变光照、pH值及GO的量增加自由基含量可提升催化效果; 采用GO/H₂O₂复合试剂比单独使用H₂O₂在48 h内对甲基橙的降解率可提高79.09%(pH=2).用改良的Hummers法制备GO成本较低,采用GO/H₂O₂复合试剂光催化降解甲基橙时,GO用量较少,且不产生危险废弃物,为实际应用中处理难降解有机物污水提供了一个绿色环保、节能高效的思路.     

ZnO复合石墨相氮化碳纳米片的制备及其光催化性能研究

为了提高石墨相氮化碳光催化性能,本文以尿素、硫脲、醋酸锌为前驱体,通过氧化热剥离与共混煅烧法分别制备g-C₃N₄纳米片和ZnO/g-C₃N₄异质结复合材料,并采用TEM、FTIR、XRD、UV-Vis DRS、BET等表征手段对制备的催化剂进行结构表征。以罗丹明、大肠杆菌为探针,考察了催化剂的光催化降解性能和抑菌活性。结果表明：以尿素和硫脲为前驱体,经过氧化热剥离处理后能得到的g-C₃N₄ 2D纳米片,其比表面积更大、光催化性能更加优异,且其对罗丹明的降解率较未剥离的g-C₃N₄提高了21.2%。在40 min氙灯照射下,纯g-C₃N₄并未表现出良好的抑菌性能,而通过ZnO复合制备的ZnO/g-C₃N₄异质结复合材料,在光催化降解率和抑菌活性方面均有很大提高,其中复合20%ZnO制得的ZnO异质结复合材料表现出最佳的光催化性能...     

Dye degradation over the multivalent charge- and solid solution-type n-MoS2/p-WO3 based diode catalyst under dark condition with a self-supporting charge carrier transfer mechanism

Pollution of water by synthetic dyes is of great concern because of the large production and usage of dyestuffs throughout the world. For dye elimination purpose, the p-n heterojunction Sb-doped MW-x composite catalysts prepared with different Mo:W precursor molar contents were synthesized via one-pot hydrothermal method. The selection in metal precursors is intended to design a composite catalyst with multiple valency in each phase. The structural, morphological, electrochemical property, and optical band gap of the composite catalyst were studied. The catalytic performance of Sb-MW composite catalysts was studied for the degradation of MB without light irradiation. It was observed that Sb-MW-4 showed superior catalytic performance to completely degrade 20 ppm MB dye solution with 20 mg catalyst in 14 min under dark condition. The composite catalyst was composed of n-(Mo,W)(O,S)₂ oxysulfide in a disordered MoS₂ framework and p-(W,Mo)(S,O)₃ sulfo-oxide in a WO₃ structure or was abbreviatedly named as n-MoS₂/p-WO₃ based catalyst. The degradation reaction for MB dye had an apparent rate constant of 3.5 × 10⁻¹ min⁻¹. This catalyst also showed excellent stability and reusability for degrading MB dye pollutant. The degradation mechanism under dark condition is proposed.     

Comparison of Tribological Properties of MoS2 and Graphite-PTFE Coatings and its Impact on Machining of Aluminium by HSS End Mills

In the present paper, a graphite–PTFE composite coating (Gr-x) on an HSS end mill is proposed for machining aluminium. The suitability of this coating was first simulated in a pin-on-disc test and was compared to the performance of MoS₂ before evaluation through machining testing. In the tribo-test, both coatings exhibited their extraordinary lubrication properties and could successfully reduce uneven frictional forces as observed with an aluminium pin against uncoated HSS. However, MoS₂-coated HSS end mills failed to produce such a favorable impact in machining. SEM images and chip morphology indicate evidence of the adherence of aluminium on the rake surface of a MoS₂-coated tool. In contrast, Gr-x coating substantially outperformed MoS₂ in the end milling test. Built-up edge (BUE) was completely arrested by Gr-x coating, and a better finish resulted from reduction of cutting force. Under the given machining conditions, the temperature was expectedly below the chemical degradation point of both coating materials and hence environmental humidity seemed to be a critical factor, which weakened the performance of MoS₂ but improved that of graphite. Cutting speeds no higher than 60 m/min are recommended for Gr-x coating during end milling of aluminium.     

g-C3N4 quantum dot decorated MoS2/Fe3O4 as a novel recoverable catalyst for photodegradation of organic pollutant under visible light

In this research, zero-dimensional (quantum dots) of graphitic carbon nitride (g-C₃N₄) and Fe₃O₄ nanoparticles were decorated on MoS₂ nanosheets to prepare MoS₂/Fe₃O₄/g-C₃N₄ quantum dots. Photocatalytic activities of newly synthesized nanocatalyst were investigated by the degradation of methylene blue (MB) and methyl orange (MO) under visible LED lamp light. In these degradation reactions, the parameters effective such as dyes concentration, pH, amount of catalyst, and irradiation time were also investigated. The systematic investigations revealed that 10 mg of MoS₂/Fe₃O₄/g-C₃N₄QDs catalyst was optimum to degrade 10 mg/L of MB and 40 mg of nanocatalyst to degrade 10 mg/L of MO with 60 W of LED irradiation. Nanocomposite can act as an excellent photocatalyst for degradation of MB and MO at short time intervals and also can be easily separated by an external magnet and reused several times. The kinetic data acquired for the degradation of dyes were matched to first-order rate equations, and also the apparent rate constants for the degradation of MB and MO were calculated as follows: K?=?0.285 min^?1 and K?=?0.263 min^?1, respectively. The novelty of catalyst is due to metal (Mo) and non-metal (S) in the structure of substrate (MoS₂), so Fe₃O₄ and g-C₃N₄ QDs can be strongly connected to the substrate. The structure and morphology of prepared nanocomposite were characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), transmission electron microscopy (TEM), scanning electron microscopy (SEM) energy dispersive X-ray spectroscopy (EDS), and UV–Vis spectroscopy.

     

CdS-sensitized ZnO nanorod arrays coated with TiO2 layer for visible light photoelectrocatalysis

A novel ZnO/CdS/TiO₂ nanorod array composite structure was fabricated by depositing CdS-sensitized layer onto ZnO nanorod arrays via chemical bathing deposition and subsequently coated by TiO₂ protection layer via a vacuum dip-coating process. The films were characterized by x-ray diffraction, field emission scanning electron microscopy, energy dispersive spectrum, and UV–Vis diffuse reflectance spectroscopy. For the films severed as the photoanodes, linear sweep voltammetry and transient photocurrent (i _ph) were investigated in a three-electrode system. The photoelectrocatalytic activity was evaluated by the degradation of methylene blue (MB) under visible light irradiation. The results show that the oriented ZnO nanorods are adhered by relatively uniform CdS-sensitized layer and coated with TiO₂ layer. Both the coated and uncoated CdS-sensitized ZnO nanorod arrays exhibit the visible light response and the photoelectrocatalytic activity on the degradation of MB under visible light irradiation. The ZnO/CdS/TiO₂ nanorod array film possesses stable and superior photoelectrocatalytic performance owing to the TiO₂ thin layer protecting the CdS from photocorrosion.     

二维纳米片层结构MoS2和其改性材料的合成及在环境领域的应用

类石墨烯的二维纳米片层状MoS_2作为过渡金属硫化物材料家族的典型代表,由于其各方面独特的性能尤其是超薄的厚度和二维结构,已成为近些年材料的研究热点。独特的三明治结构使其具有良好的物理化学性质,MoS_2及其复合材料在催化、传感器、润滑等方面有广阔的前景。总结了国内外MoS_2的合成及其改性方法、性能和应用。针对社会发展过程中日益严重的环境污染问题,重点介绍利用其吸附和催化性能去除环境中污染物,并对其未来发展进行了展望。     

Synthesis of MoS2/C nanocomposites by hydrothermal route used as Li-ion intercalation electrode materials

MoS₂/C nanocomposites were synthesized by a facile hydrothermal route employing sulfocarbamide, sodium molybdate and D-grouse as starting materials. XRD analysis showed that the MoS₂ was a two-dimensional nanosheet crystal and C was retained as amorphous after their calcinations at 800 °C. TEM images showed that MoS₂ was uniformly dispersed in the amorphous carbon. The MoS₂/C composites exhibited high reversible capacity and excellent cyclic performance when used as Li-intercalation electrodes. The improvements in electrochemical performance are attributed to the incorporation of amorphous carbon, which can suppress the aggregation and pulverization of active materials, and keep the active materials electrically connected.     

超声协同微球型Bi2O2CO3降解罗丹明B的研究

Bi_2O_2CO_3是一种Bi类半导体催化剂,文章研究了它的超声催化性能。首先,采用水热法制备了微球型的Bi_2O_2CO_3,利用X射线衍射(X-ray Diffraction, XRD)、扫描电子显微镜(Scanning Electron Microscope, SEM)、紫外-可见漫反射光谱对样品的晶体结构、微观形貌、光学特性进行了表征。然后,以罗丹明B(Rh B)作为模型污染物,通过研究超声催化降解罗丹明B来评测Bi_2O_2CO_3的超声催化性能。研究了催化剂的浓度(Ccatalytic)、初始罗丹明B染料的浓度(CRhB)和超声功率(P)等实验因素对超声催化降解效率的影响。得出在Ccatalytic=3 g·L-1,CRhB=10 mg·L-1和P=400 W条件下降解罗丹明B的效率最高,其最高降解效率可以达到91.7%。     

Investigation of failure mechanism and modification for film-lubricated precise angular-contact ball bearing

This paper describes an experimental investigation into the performance and lubrication failure mechanism of precise angular-contact ball bearings treated with MoS₂-sputtered film, etc. As an important executive component of various spacecrafts, there are some strict requirements on the lubrication performance of angular-contact ball bearing, but the related experimental data are rare to see in literatures. In this experiment, the lubrication performances of MoS₂-sputtered ball bearing pairs were evaluated by using lifetime test as a main method, and the topographies and compositions of working surfaces were investigated through SEM, AES and EDS. The systematical experiment results reveal that the degradation and failure process of solid lubrication for such ball bearing is divided into three stages with different characters. A supposed failure mechanism has been proposed. An improved lubrication treatment based on above mechanism was conducted for the precise ball bearings, and a later test showed that long endurance life with more than 10⁸ revolutions has been reached.     

An efficient photo-catalytic VOC removal process by one-pot synthesized N-F/TiO2 nanoparticles in fluidized-spouted bed reactor

Photocatalytic degradation under visible light irradiation is an important task of using solar energy for the removal of environmental pollutants. N-F/TiO₂ nanoparticles were synthesized in one-pot sol–gel condition using tetra-isopropyl-orthotitanate as the TiO₂ precursor and NH₄F as the N-F doping source. Diffuse reflectance spectroscopy (DRS) analysis of the material has shown a reduction of band gap energy and shifting absorption edge to the visible wavelengths. A fluidized-spouted bed reactor equipped with the light source was designed and constructed for the oxidation process of VOC from the high airflow rate under Hg lamp irradiation using synthesized N-F/TiO₂ nanoparticles. Acetaldehyde was used as the air pollutant model molecule of VOC in this process. The effluent acetaldehyde concentration was analyzed continuously along the time by an online Gas Chromatography (GC) from the start up to reaching steady conditions. The results have revealed significant enhancement of acetaldehyde removal by the N-F/TiO₂ sample fabricated with an equal weight ratio of NH₄F/Ti. After steady conditions, almost 100% removal of acetaldehyde was observed in the spouted bed reactor from a high airflow stream of 5?L/min polluted with 1000?ppm acetaldehyde at room-temperature conditions, under 80?W Hg with 500 Lux intensity.