g-C3N4/MoS2纳米片异质复合物的球磨法制备及可见光催化性能研究

采用球磨法制备g-C₃N₄/MoS₂纳米片异质复合物,运用X-射线衍射仪、高分辨透射电镜、紫外可见漫反射光谱和荧光发射光谱对异质复合物的结构和形貌进行了表征。结果表明：MoS₂纳米片可进入g-C₃N₄的层间形成异质复合物。以罗丹明B为模拟污染物,在可见光照射下考察了复合物的光催化特性。结果显示,含有2%的MoS₂纳米片与g-C₃N₄形成的异质复合物在120min内对罗丹明B降解率为98%,其降解动力学常数是体相g-C₃N₄为的4.3倍。g-C₃N₄/MoS₂纳米片异质复合物具有十分优良的光催化特性。其催化活性的提高主要归因于光生电子和空穴的有效分离和传输,并根据光捕获实验提出复合物可能的光催化机理。     

水热法制备C3N4/CuGaO2 复合物及其气敏性能

采用简单水热法合成了一系列C₃N₄/CuGaO₂复合材料。采用XRD、SEM、TEM和XPS对制备的样品进行了表征。研究了一系列C₃N₄/CuGaO₂复合材料的气敏性能。结果表明,基于C₃N₄/CuGaO₂-0.3复合材料（C₃N₄与CuGaO₂的摩尔比为0.3:1）的气体传感器对甲苯的传感性能优于CuGaO₂传感器。相比较于CuGaO₂传感器的工作温度（140 ℃）,C₃N₄/CuGaO₂-0.3复合材料传感器的最佳工作温度仅为25 ℃,对100 μL/L甲苯气体的响应达到28,检出限低至0.01 μL/L。对100 μL/L甲苯气体的响应时间和恢复时间分别为114.2和27.4 s。此外,用于检测甲苯的C₃N₄/CuGaO₂-0.3复合材料传感器还具有优异的长期稳定性、良好的重复性和优异的抗湿性能。     

纳米Si3N4 对TC4钛合金微弧氧化层微观结构和性能的影响

在基电解液中加入氮化硅纳米颗粒,对TC4钛合金进行微弧氧化（MAO）处理,研究了Si₃N₄浓度对微弧氧化层表面形貌、耐蚀性和耐磨性的影响。添加Si₃N₄的MAO层呈现多孔结构,当Si₃N₄浓度为1 g/L时,涂层厚度最大,且经过7 d的酸腐蚀试验,该涂层的耐蚀性良好,腐蚀速率最低,约为0.057 mg·cm^-2·d^-1。随着Si₃N₄的加入,MAO涂层的抗菌性能先升高后降低。当Si₃N₄的添加量为1 g/L时,该MAO层的抗菌性能最好。Si₃N₄的加入能明显提高涂层在模拟海水中的耐磨性。当Si₃N₄的添加量为3和4 g/L时,所得涂层的摩擦系数低且稳定,且添加3 g/L Si₃N₄制备来的MAO涂层表现出优异的耐磨性。     

Fe3O4/SiO2/Bi2WO6磁性复合光催化剂的制备及其光催化性能

钨酸铋(Bi₂WO₆),结构最简单的Aurivillius相化合物,是近期受到研究者关注的新型光催化材料。然而,光催化剂粉末在反应介质中难被回收,工业化应用成本较高。本文用三步方法合成了可回收的Fe₃O₄/SiO₂/Bi₂WO₆磁性复合光催化剂,通过溶剂热法合成具有磁性的Fe₃O₄,用溶胶凝胶法在Fe₃O₄表面覆盖SiO₂层,后将磁性颗粒与Bi₂WO₆纳米片相结合。光催化剂的形貌结构及性能通过XRD、SEM、PL、UV-vis进行表征测试。结果表明,直径约500 nm的Fe₃O₄微球附着在边长约500 nm的Bi₂WO₆纳米片的表面,SiO₂在两者之间起到了粘连作用。光催化剂Fe₃O₄/SiO₂/Bi₂WO₆对于罗丹明B的光降解活性较好,且有一定磁性,可以通过外加磁场将其从溶液中分离,有较大的应用潜力。     

La2O3掺杂AgSnO2电接触材料的制备及性能研究

以Ag、Sn、La₂O₃粉为原料,采用机械合金法制备复合粉体。结合氧化法与粉末冶金工艺,对复合粉体进行氧化、压制、烧结。采用扫描电镜(SEM)和能谱仪、硬度计、金相显微镜、金属电导率测量仪等对复合粉体氧化前后的形貌以及电接触材料烧结前后的性能进行表征。结果表明：烧结后,电接触材料硬度较于烧结前明显下降。同时电接触材料随Sn含量增大,电阻率升高,密度反而下降。在一定的La₂O₃(0wt.%、0.75wt.%、1.5wt.%、2.25wt.%、3wt.%)含量范围内,La₂O₃掺杂量越高,密度越低。同时电接触材料经烧结后,随La₂O₃含量增加,其电阻率先降后升,在La₂O₃含量为0.75wt.%时,电接触材料的电阻率最低。     

环境障涂层用纳米结构Yb2SiO5粉体喂料的制备与表征

纳米结构稀土硅酸盐涂层被认为是未来新型环境障涂层的发展方向,其中 Yb₂ SiO₅ 由于与中间层莫来石的热物性能匹配良好、优异的抗水氧腐蚀能力成为非常有发展前景的环境障涂层面层候选材料。 从材料制备的角度出发, 探索纳米结构 Yb₂ SiO₅ 喂料制备工艺并对喂料进行物相、组织结构和性能表征。 采用喷雾造粒加固相烧结的方法制备了纳米结构 Yb₂ SiO₅ 喷涂粉体喂料,探索了制备高纯度 Yb₂ SiO₅ 的固相烧结工艺,后续通过等离子处理改善粉体喂料的喷涂性能。 借助 X 射线衍射仪研究了粉体喂料的物相,采用扫描电镜、透射电镜研究了粉体喂料的形貌与微观结构。 结果显示,固相烧结工艺采用在 1500 ℃下保温 4 h,再将得到的粉体喂料等离子处理可得到高纯度的 Yb₂ SiO₅ 喷涂粉体喂料,等离子处理之后的喂料为纳米结构,喂料粒度分布均符合等离子喷涂要求,喂料具有良好的流动性和致密性。     

TiZrNiCu钎焊Si3N4-MoSi2复合陶瓷与Nb接头组织与力学性能

采用高温活性钎料TiZrNiCu对Si₃N₄-MoSi₂复合陶瓷和金属Nb进行真空钎焊试验,研究了其典型界面组织组成及形成机理,分析了钎焊温度和保温时间对钎焊接头界面组织及力学性能的影响规律。结果表明,接头典型界面结构为Nb/β-Ti/(Ti. Zr)₂(Cu, Ni)+β-Ti+(Ti, Zr)₅Si₃/TiN+(Ti, Zr)₅Si₃+MoSi₂/Si₃N₄-MoSi₂。钎焊温度和保温时间主要通过控制Si₃N₄-MoSi₂复合陶瓷母材中Si原子向钎料中扩散程度,来影响钎缝中(Ti, Zr)₅Si₃化合物的数量及分布,进而影响钎焊接头的抗剪强度。在920 ℃/10 min的工艺参数下,Si₃N₄-MoSi₂/Nb接头的室温抗剪强度最高达到112 MPa,选择最优参数条件下的Nb/Si₃N₄-MoSi₂钎焊接头在500 ℃和600 ℃条件下进行高温剪切实验,其高温抗剪强度分别达到123 MPa和131 MPa。     

Cr3+掺杂LiNi0.5Mn1.5O4材料的制备及性能研究

采用高温固相法合成了Cr₃₊掺杂的LiNi_0.5Mn_1.5O₄正极材料,研究了掺杂量对材料物理性能和电化学性能的影响。利用XRD、SEM对材料的结构和形貌进行了表征,结果显示样品具有棱边清晰的尖晶石形貌。讨论了不同Cr₃₊掺杂量对LiCr_xNi_0.5-0.5xMn_1.5-0.5xO₄(x=0,0.05,0.1,0.15,0.2)正极材料性能的影响。充放电测试、循环伏安和交流阻抗测试结果表明：当Cr₃₊的掺杂量为x=0.1时(LiCr_0.1Ni_0.45Mn_1.45O₄)正极材料的性能最好,0.1C、0.5C、1C、2C及5C的首次放电比容量依次为131.54mAh g_-1、126.84mAh g_-1、121.28mAh g_-1、116.49mAh g_-1和96.82mAh g_-1,1C倍率下循环50次,容量保持率仍为96.5%。     

纳米柱状多孔WO3- x /TiO2 薄膜的电致变色性能

采用反应磁控溅射在掠射角度α=0°和α=80°的条件下制备氧化钨（WO_3-x）薄膜,然后在其表面沉积二氧化钛（TiO₂）。利用X射线衍射仪（XRD）、场发射扫描电镜（FE-SEM）和X射线光电子能谱仪（XPS）对WO_3-x/TiO₂薄膜的晶体结构、表面/断面形貌以及表面化学成分进行表征。在三电极体系1 mol/L LiClO₄/PC溶液中,采用电化学工作站和紫外-可见分光光度计测试了WO_3-x/TiO₂薄膜的电致变色性能。XRD结果表明,WO_3-x/TiO₂薄膜为非晶态结构,与掠射角度无关。当掠射角度为80°时,获得了纳米柱状多孔薄膜。从 W 4f和Ti 2p的XPS谱图确认氧化钨为亚化学计量比的WO_3-x,而氧化钛为满足化学计量比的TiO₂。与致密薄膜相比,纳米柱状多孔薄膜需要较低的驱动电压且具有较快的响应速度。纳米柱状多孔薄膜的电荷容量为83.78 mC,是致密薄膜电荷容量30.83 mC的2倍以上。在±1.2 V驱动电压下,注入和脱出离子扩散速率分别为D_in=5.69×10^-10 cm²/s和D_de= 5.08×10^-10 cm²/s。与纯WO₃薄膜相比,WO_3-x/TiO₂薄膜的电致变色循环稳定性更好。纳米柱状多孔薄膜在可见光范围内具有较大的光调制幅度,因此其光密度变化（ΔOD）大于致密薄膜。     

Ar/N2-Ar共溅射Ti掺杂对Ta2O5 涂层光学和力学性能的影响

为了探索Ar/N₂-Ar共溅射Ti掺杂对Ta₂O₅涂层光学性能和力学性能的影响,采用射频和直流磁控共溅射技术在玻璃基底表面制备了Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层。利用X射线衍射仪（XRD）、扫描电子显微镜（SEM）、原子力显微镜（AFM）表征了Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层的微观结构和表面形貌;通过紫外可见分光光度计测试了涂层的光学参数;采用纳米压痕仪测试了涂层的硬度和杨氏模量。XRD测试结果表明,Ta₂O₅、N₂-Ta₂O₅、Ti-Ta₂O₅和N₂-Ti-Ta₂O₅涂层主要以Ta₂O₅为主体的非晶相结构组成。SEM和AFM结果显示,沉积在玻璃基底上的涂层未出现大面积空隙,溅射粒子在基底表面均匀堆积生长,并且涂层沉积厚度基本一致,厚度误差在5%以内。分别引入N₂和Ti及N₂-Ti共掺杂,均可降低Ta₂O₅涂层的粗糙度。光学测试结果表明,分别引入N₂和Ti元素,可以提高Ta₂O₅涂层的平均透射率至81%以上,而N₂-Ti共掺杂制备的N₂-Ti-Ta₂O₅涂层平均透射率降低。力学测试结果显示,与Ta₂O₅涂层对比,N₂-Ta₂O₅和N₂-Ti-Ta₂O₅涂层的硬度显著增大,Ti-Ta₂O₅涂层硬度基本一致。弹性指数（H/E）和塑性指数（H³/E²）表明,N₂-Ta₂O₅涂层和N₂-Ti-Ta₂O₅涂层具备更好的断裂韧性和抗塑性变形能力。在玻璃表面制备Ta₂O₅掺杂N₂和Ti元素的涂层,可以实现以N₂-Ta₂O₅涂层和N₂-Ti-Ta₂O₅涂层为代表的、同时具备优异光学性能和力学性能的多功能涂层。     

TiO2-g-C3N4 composite materials for photocatalytic H2 evolution under visible light irradiation

In this investigation, we report the preparation of TiO₂-g-C₃N₄ composite materials with varying the wt.% of g-C₃N₄, the characterization of these materials by various techniques and photocatalytic hydrogen production under visible light irradiation in the presence of methanol. The X-ray powder diffraction (XRD) shows that the composite materials are consist of anatase TiO₂ and g-C₃N₄. Fourier transform infrared (FT-IR) spectra show that the absorbance band intensity of composite materials was stronger than that of C₃N₄. The UV-vis absorption spectra show that the absorption edge of the composite materials shifts to the lower energy region comparing to pure anatase and to longer wavelengths with increasing the amount of C₃N₄. The significant photoluminescence quenching was observed in TiO₂-C₃N₄ composite materials, indicating the charge transfer from C₃N₄ to TiO₂. The visible light induced H₂ evolution rate was remarkably enhanced by coupling TiO₂ with C₃N₄.     

废旧锂离子电池中Li, Fe和V的回收及xLiFePO4-yLi3V2(PO4)3的制备

由于LiFePO_4和Li_3V_2(PO_4)_3材料的特征相近,制备方法类似,提供了一种从废旧LiFePO_4和Li_3V_2(PO_4)_3混合电池中回收Li、Fe和V,再制备xLiFePO_4-yLi_3V_2(PO_4)_3的方法。在空气气氛中600℃热处理1h后,去除粘结剂PVDF使活性物质与集流体分离。调节Li、Fe、V和P摩尔比,球磨、锻烧,配制不同比例的xLiFePO_4-yLi_3V_2(PO_4)_3(x:y=5:1,7:1,9:1)复合电极材料。表征了其形貌、结构和电化学性能,结果表明,回收制备的复合材料将同时具备LiFePO_4和Li_3V_2(PO_4)_3两种材料的电化学性能,能显著改善LiFePO_4的倍率性能。     

B参杂对NiO/Ni(OH)2电极材料电容性能的影响

通过化学镀再电化学氧化的方法在铜片表面制备出带有微米微坑和微米微球的均一NiO/Ni(OH)₂和B参杂的NiO/Ni(OH)₂(B)两种电极材料,采用扫描电镜(SEM/EDX)、X射线衍射(XRD)、X射线光电子能谱(XPS)和电化学技术对所制备的两种电极材料进行表征和电化学性能测试。SEM、XRD和XPS的测试结果表明, 所制备的两种电极材料由Ni、NiO和Ni(OH)₂组成,并且NiO/Ni(OH)₂(B)中B的参杂量可达14.6wt%。循环伏安测量和恒电流充放电试验表明,两种电极材料均具有较高的电化学活性和可逆性;在1 A/g的充放电电流密度下, 两种NiO/Ni(OH)₂和NiO/Ni(OH)₂(B)电极材料经历10000次充放电循环后分别给出了1380 和1930F/g的比电容, 显示出较高的比电容特性和良好的电化学稳定性;电化学阻抗谱表明NiO/Ni(OH)₂(B)电极材料较NiO/Ni(OH)₂电化学反应电阻降低了约2个数量级;Ragone曲线揭示了所制备的两种电极材料具有较高的功率密度和较低的能量密度。B的参杂使得NiO/Ni(OH)₂(B)电极材料表面氧化物含量增大并且形成微米微球形貌,增大了电极表面积以及与电解液的接触和润湿作用,降低了电极材料表面能带带隙能,从而导致较小的电化学反应电阻和电导率的提高是其显示优异赝电容性能的主要原因。     

固相-水热法制备LiFePO4-Li3V2（PO4）3复合材料及其电化学性能（英文）

分别采用固相-水热法和球磨法制备磷酸亚铁锂-磷酸钒锂复合正极材料(LiFePO4-Li3V2(PO4)3)。电化学性能测试表明,LiFePO4-Li3V2(PO4)3复合正极材料的电化学性能远远高于 LiFePO4和 Li3V2(PO4)3单独作为正极材料的性能,并且以固相-水热法制备的复合材料性能优于以球磨法制得的复合材料。研究发现 LiFePO4-Li3V2(PO4)3复合材料有 4 个氧化还原峰,相当于 LiFePO4 和 Li3V2(PO4)3 氧化还原峰的叠加。采用固相-水热法制备的LiFePO4-Li3V2(PO4)3 复合材料形貌较为规则,且有新相物质产生,这是导致其电化学性能较好的原因。     

Sol-gel synthesis and electrochemical performance of Li4Ti5O12/graphene composite anode for lithium-ion batteries

Li₄Ti₅O₁₂/graphene composite was prepared by a facile sol-gel method. The lattice structure and morphology of the composite were investigated by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The electrochemical performances of the electrodes have been investigated compared with the pristine Li₄Ti₅O₁₂ synthesized by a similar route. The Li₄Ti₅O₁₂/graphene composite presents a higher capacity and better cycling performance than Li₄Ti₅O₁₂ at the cutoff of 2.5-1.0 V, especially at high current rate. The excellent electrochemical performance of Li₄Ti₅O₁₂/graphene electrode could be attributed to the improvement of electronic conductivity from the graphene sheets. When discharged to 0 V, the Li₄Ti₅O₁₂/graphene composite exhibited a quite high capacity over 274 mAh g⁻¹ below 1.0 V, which was quite beneficial for not only the high energy density but also the safety characteristic of lithium-ion batteries.     

Electrochemical hydrogen absorbing properties of graphite/AB5 alloy composite electrode

Graphite is an inexpensive carbon material, but its hydrogen absorbing performance has attracted little attention. In this paper, in order to lower the cost of nickel metal-hydride (Ni-MH) battery, graphite is used as a hydrogen absorbing material in its negative electrode. The results of charge-discharge tests show that the graphite electrode has poor electrochemical hydrogen absorbing performance. The capacity of the graphite/AB₅ alloy (90 wt%) composite electrode is close to AB₅ alloy (298 mAh/g), but it has higher charge-discharge polarization and difficulty in activation. When graphite is modified with metal nickel powder by a simple ball milling process, the capacity of the composite electrode reaches to 315 mAh/g and its activation is accelerated. The results of electrochemical impedance spectroscopy (EIS) tests show that hydrogen diffusion in the modified composite electrode is more rapid than in AB₅ alloy, thereby resulting in lower charge-discharge polarization and better discharge performance at large currents.     

Structure and electrochemical performance of FeF3/V2O5 composite cathode material for lithium-ion battery

Orthorhombic structure FeF₃ was synthesized by a liquid-phase method using FeCl₃, NaOH and HF solution as starting materials, and the FeF₃/V₂O₅ composites were prepared by milling the mixture of as-prepared FeF₃ and the conductive V₂O₅ powder. The properties of FeF₃/V₂O₅ composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), galvanostatic charge/discharge and cyclic voltammetry measurements. Results showed that the FeF₃/V₂O₅ composites can be used as cathode material for lithium-ion battery. Electrochemical measurements in a voltage range of 2.0–4.5 V reveal that the addition of conductive V₂O₅ improves significantly the electrochemical performance of FeF₃, and the FeF₃/V₂O₅ composite prepared by milling for 3 h exhibits high discharge capacity and good cycle performance, and its discharge capacity maintains about 209 mAh g⁻¹ at 0.1 C (23.7 mA g⁻¹) after 30 cycles.     

Effects of pelletization of reactants and diluents on the combustion synthesis of Si3N4 powder

Reactants were pelletized, and then combustion synthesis of Si₃N₄ powder was achieved under the N₂ pressure of 3.0 MPa. Effects of the pelletization of reactants and Si₃N₄ diluents on the combustion process parameters and the characteristics of products were studied. The combustion mode of single reactant pellet was preliminarily discussed. The results indicated that the combustion reaction of single pellet was layer-by-layer from the surface to the core, which led to two peaks on the combustion temperature variation waves. With increasing the diluents content, the morphologies of Si₃N₄ particles changed from short rods into equiaxed grains, and residual Si in the final products obviously decreased. Single phase β-Si₃N₄ powder mainly contained equiaxed grains was prepared when 58 wt.% diluents was added.     

Deposition and characterization of CrN/Si3N4 and CrAlN/Si3N4 nanocomposite coatings prepared using reactive DC unbalanced magnetron sputtering

Nanocomposite coatings of CrN/Si₃N₄ and CrAlN/Si₃N₄ with varying silicon contents were synthesized using a reactive direct current (DC) unbalanced magnetron sputtering system. The Cr and CrAl targets were sputtered using a DC power supply and the Si target was sputtered using an asymmetric bipolar-pulsed DC power supply, in Ar + N₂ plasma. The coatings were approximately 1.5 μm thick and were characterized using X-ray diffraction (XRD), nanoindentation, X-ray photoelectron spectroscopy and atomic force microscopy. Both the CrN/Si₃N₄ and CrAlN/Si₃N₄ nanocomposite coatings exhibited cubic B1 NaCl structure in the XRD data, at low silicon contents (< 9 at.%). A maximum hardness and elastic modulus of 29 and 305 GPa, respectively were obtained from the nanoindentation data for CrN/Si₃N₄ nanocomposite coatings, at a silicon content of 7.5 at.%. (cf., 24 and 285 GPa, respectively for CrN). The hardness and elastic modulus decreased significantly with further increase in silicon content. CrAlN/Si₃N₄ nanocomposite coatings exhibited a hardness and elastic modulus of 32 and 305 GPa, respectively at a silicon content of 7.5 at.% (cf., 31 and 298 GPa, respectively for CrAlN). The thermal stability of the coatings was studied by heating the coatings in air for 30 min in the temperature range of 400-900 °C. The microstructural changes as a result of heating were studied using micro-Raman spectroscopy. The Raman data of the heat-treated coatings in air indicated that CrN/Si₃N₄ and CrAlN/Si₃N₄ nanocomposite coatings, with a silicon content of approximately 7.5 at.% were thermally stable up to 700 and 900 °C, respectively.     

Characterization and electrochemical properties of carbon-coated Li4Ti5O12 prepared by a citric acid sol-gel method

Since carbon coating can effectively improve electrical wiring of Li₄Ti₅O₁₂ and thus enhance its high rate performance, a novel and simple citric acid sol-gel method for in situ carbon coating is employed in this study. The effects of the amount of the carbon source in the starting xerogel on the particle size, the resistance and the electrochemical performance of the synthesized Li₄Ti₅O₁₂ samples are systematically studied. The physical and electrochemical properties of the obtained samples have been characterized by XRD, TG-DSC, SEM, TEM, BET, A.C. impedance, galvanostatically charge-discharge and cyclic voltammetry tests. The results show that the initial amount of the carbon source in the starting xerogel is a critical factor which determines the content of the coated carbon and the pore volume, therefore governs the high rate performance of the Li₄Ti₅O₁₂/C composites. The Li₄Ti₅O₁₂/C composite with in situ carbon coating of 3.5 wt% exhibits the best electrochemical performance which delivers delithiation capacities of 143.6 and 133.5 mAh g⁻¹ with fairly stable cycling performance even after 50 cycles at 0.5C and 1C rate, respectively.