CO2/N2在HP-MOF-74(ZnxNi1-x)上的吸附性能探究

以SDBS为模板剂,采用水热合成法制备了不同比例的双金属HP-MOF-74(Zn_xNi_1-x)材料,利用XRD、FT-IR、SEM等对其物化性能进行了研究;以烟道气CO₂和N₂为吸附质,使用静态容量法在273 K和298 K处测试了三种不同HP-MOF-74(Zn_xNi_1-x)材料上CO₂和N₂的等温线;根据理想吸附溶液理论(IAST)估算了CO₂/N₂二元混合物的吸附选择性;此外,使用克-克方程计算了等量吸附热(QST)。     

Mg2+掺杂对富锂层状氧化物材料Li1.2Mn0.54Ni0.13Co0.13O2的影响

Mg²⁺作为一种电化学惰性的阳离子,由于其离子半径(0.072 nm)与Li⁺的离子半径(0.076 nm)相近,因此被广泛应用于取代富锂层状氧化物(LLOs)材料中Li⁺的位置。然而,Mg²⁺对LLOs材料晶体结构的影响还存在争议。利用溶胶凝胶法成功制备了一系列Mg²⁺掺杂富锂正极材料Li_1.2-xMg_xMn_0.54Ni_0.13Co_0.13O₂,通过X射线衍射仪和X射线光电子能谱等对其晶体结构和元素价态进行了系统的研究。结果表明,Mg²⁺掺杂导致LLOs材料晶胞参数的增加。通过与Li_1.2Mn_0.54Ni_0.13Co_0.13O₂材料的电化学性能对比发现,Mg²⁺掺杂有效地提高了LLOs材料的电化...     

Fe-Co-N-C氧还原催化剂的制备及性能

为了提高氮掺杂碳(N-C)材料的氧还原性能,采用后吸附法基于可在高温炭化过程中形成富缺陷碳材料及均匀分散的高活性M-N_x位点的沸石咪唑酯骨架-8衍生制备了Fe-Co-N-C催化剂。电化学测试结果表明采用150 mg Co-N-C催化剂吸附0.07 mmol Fe制备的Fe-Co-N-C催化剂在0.1 mol/L HClO₄中具有较高的半波电位(0.843 V vs. RHE)和较低的过氧化氢产率(<4%)。物性表征结果表明Fe-Co-N-C催化剂的优异氧还原活性可归因于其双金属活性位点(Fe/Co-N_x)、丰富的微/介孔结构、较高的石墨化程度以及Fe/Fe₃C和Fe-N_x的共同作用。     

水热法制备3D rGO/Co3O4-x复合材料及超电容性能研究

利用一步水热合成法,以氧化石墨烯(GO)和六水合硝酸钴(Co(NO₃)₂·6H₂O)为实验原料,简易制备了含氧空位的3D还原氧化石墨烯/四氧化三钴(3D rGO/Co₃O_4-x)复合电极材料.通过扫描电镜、透射电镜观察,Co₃O_4-x呈线状或球状均匀分布在多孔网络结构的3D rGO上,表明了3D rGO/Co₃O_4-x复合材料的成功制备.在2 mV/s的扫描速率下,基于Co₃O_4-x质量比电容为635.7 F/g.将复合电极材料组装成对称型超级电容器,在功率密度为100 W/kg时,得到的能量密度为10.6 Wh/kg.经过10 000次电化学循环后的电容保持率为98.15%.对称型超级电容器优异的电化学性能归因于石墨烯高的比表面积、良好的多孔性以及Co₃O_4-x与石墨烯之间的协同效应.     

Zr4+掺杂对Na4-xMnV1-xZrx(PO4)3的结构和电化学性质的影响

为了改善Na₄MnV(PO₄)₃的电化学性能,采用溶胶-凝胶法与高温固相法在750℃下烧结10 h制得了不同Zr⁴⁺掺杂浓度的Na_4-xMnV_1-xZr_x(PO₄)₃钠离子电池正极材料。通过X射线衍射和扫描电子显微镜研究Zr⁴⁺离子掺杂对Na_4-xMnV_1-xZr_x(PO₄)₃结构演变和电化学性能的影响。结果显示：半径为80 pm的Zr⁴⁺离子部分取代半径为74 pm的V³⁺离子后,材料的晶胞体积增大,这有利于Na⁺的快速扩散。电化学性能结果表明,Na_3.9MnV_0.9Zr_0.1(PO₄)₃     

(LaCa3)0.5-xMg1+4xNi9(x=0,0.02,0.04,0.06,0.08,0.1)合金微观结构及储氢性能研究

AB₃型La-Mg-Ni系列储氢合金由于储氢容量优异、放电容量高、活化快等优势受到储能领域的关注.采用真空感应熔炼法制备了(LaCa₃)_0.5-xMg_1+4xNi₉(x=0,0.02,0.04,0.06,0.08,0.1)合金,表征合金的微观结构并测试储氢合金性能差异,研究合金A侧元素比例对合金性能影响的内在机理.合金活化性能受Mg元素取代量的影响明显,活化吸放氢速率随着Mg质量分数的增加先增加后减小.随着Mg替代量的增加,合金的最大吸放氢容量分别由1.866%和1.311%提高到1.972%和1.732%,吸放氢焓变绝对值分别由15.71 kJ/mol和17.88 kJ/mol降低到8.88 kJ/mol和9.28 kJ/mol,其热稳定性降低,这对改善热力学性能有积极作用.     

ZrxCe1-xO2/NC催化CO2和苯乙烯-锅法制环碳酸酯

CO₂与烯烃转化为环碳酸酯是当前一种有效的固碳策略,为此设计了一种掺氮多孔碳负载锆铈双金属(Zr_xCe_1-xO₂/NC)催化剂。通过X射线衍射(XRD)、扫描电子显微镜(SEM)、 N₂-吸附、 CO₂和NH₃程序升温脱附(CO₂-TPD和NH₃-TPD)等表征了催化剂的形貌、物相、孔结构以及酸碱两性特征。结果表明,该催化剂可在无卤条件下催化CO₂和苯乙烯一锅法制备环碳酸酯,特别是Zr_0.75Ce_0.25O₂/NC在2 MPa CO₂下,采用80℃/8 h和150℃/8 h分段工艺,实现了74.87%的转化率和80.43%的环碳酸酯选择性,这归因于氧化铈(CeO₂)和氧化锆(ZrO₂)在碳载体上的均匀分散,以及丰富的酸-碱性位点协同作用。     

PW12/Bi2WO6复合材料的制备及光催化性能的研究

采用两步法合成新型可见光驱动的PW₁₂/Bi₂WO₆复合材料，利用XRD、SEM、TEM、IR、EDX表征技术对复合材料进行物理和光学性质的分析，并以亚甲基蓝(MB)为模拟污染物对其催化剂活性进行测试。实验结果显示，与纯Bi₂WO₆相比，引入PW₁₂的催化剂光催化活性显著提升。当m(PW₁₂)/m(Bi₂WO₆)=2∶8、复合催化剂煅烧温度为400℃、MB浓度为10 mg/L、复合催化剂投加量为0.1 g时，PW₁₂/Bi₂WO₆的光催化活性最佳，光照1.5 h后对MB的去除率达90.87%,2 h后可达99.71%。     

Pt/CoMoO4纳米复合材料的制备及对葡萄糖电催化

超灵敏和高抗干扰性葡萄糖检测对于糖尿病的临床诊断相当重要。采用水热法在泡沫镍基体上生长CoMoO₄纳米棒,进一步利用电化学沉积技术在CoMoO₄上制备纳米Pt,获得Pt/CoMoO₄复合材料。扫描电子显微镜显示纳米Pt的直径约为30 nm,均匀分散在CoMoO₄纳米棒表面。利用循环伏安法和计时安培法研究了不同材料对葡萄糖的电催化性能,结果表明, Pt/CoMoO₄具有优异的葡萄糖检测性能,响应电流与葡萄糖浓度在1μmol/L～0.5 mmol/L和0.5～3 mmol/L范围内呈现良好的线性关系,灵敏度为4.59 mA·mmol·L^-1·cm^-2,检测限为0.3μmol/L,显现了纳米Pt与CoMoO₄纳米棒的协同效应。该电极具有响应时间短、灵敏度高、抗干扰能力强等优点,是一种成本低、实用性能高的葡萄糖检测电极。     

聚苯胺插层三氧化钼复合光催化剂的制备及性能

以苯胺柱撑的三氧化钼有机-无机杂化体为反应前躯体,在空气气氛下于120 ℃进行氧化聚合,制备了一种聚苯胺插层MoO₃ 复合材料。以罗丹明B(RhB)为目标降解物,以MoO₃ 复合材料为光催化剂,考察了其催化性能,并研究了光照时间、催化剂质量浓度和pH 与光催化降解效率的关系。结果表明,在pH 为1~4、催化剂的质量浓度为0.30~0.40g/L、光照时间2.0h的条件下,MoO₃/PANI复合材料对罗丹明B具有良好的光降解效果,降解率最高可达98.00%。     

The Effect of Surface Etching and Dation on the Permeability Spectrum of Nanoerystalline Fe85-xCoxNb7B8 Ribbon

Etching and oxidation were adopted to improve the frequency dependence of permeability of nanocrystalline Fe85-xCoxNb7B8 ribbons. The effect of etching and oxidation on the permeability spectrum of nanocrystalline Fe85-CoxNb7B8 ribbons was investigated. The relaxation frequency shifted to higher frequency end after etching and oxidation while the amplitude of μ1 was reduced at the same time. As a whole, μf0 rises and reflects the increasing of resistivity after etching and oxidation.     

Electrocatalytic activity of tungsten trioxide microspheres, tungsten carbide microspheres and multi-walled carbon nanotube-tungsten carbide composites

Tungsten trioxide micropheres were prepared by spray pyrolysis, and tungsten carbide microspheres were produced by spray pyrolysis-low temperature reduction and carbonization technology. Multi-walled carbon nanotube-tungsten carbide composites were prepared by the continuous reduction and carbonization process using multi-walled carbon nanotubes (MWCNTs) and WO₃ precursor by molecular level mixing and calcination. The morphology and structure of the samples were characterized by scanning electron microscope and transmission electron microscope. Furthermore, the crystal phase was identified by X-ray diffraction. The electrocatalytic activity of the sample was analyzed by means of methanol oxidation. Tungsten carbide microspheres were catalytic active for methanol oxidation reaction. Nevertheless tungsten trioxide microspheres and multi-walled carbon nanotube-tungsten carbide composites were not catalytic active for methanol oxidation reaction. These results indicate that tungsten carbide micropheres are promising catalyst for methanol oxidation.     

磷掺杂碳纳米管负载镍催化剂的小分子电氧化性能研究

镍基催化剂作为碱性溶液中高催化活性和稳定的非贵金属催化剂,广泛用于小分子电催化氧化领域研究。以磷掺杂碳纳米管为载体,将负载镍/氧化镍核壳的纳米粒子用于甲醇小分子的电氧化,获得了良好的稳定性及催化活性。在仅有3%的低负载量时,在氧化峰电位,其质量活性为6 800 mA/mg,未掺杂碳纳米管载体上负载的纳米粒子活性仅为2 070 mA/mg。而且,与CNTs相比,PCNTs为载体时甲醇电氧化的起始电位及氧化电位均有一定程度的负移。该高催化性能归因于镍/氧化镍核壳纳米粒子的小粒径,以及磷掺杂碳纳米管载体与金属之间的相互作用。     

Nanostructure and formation mechanism of Pt-WO<Subscript>3</Subscript>/C nanocatalyst by ethylene glycol method

Pt-WO3 nanoparticles uniformly dispersed on Vulcan XC-72R carbon black were prepared by an ethylene glycol method.The morphology,composition,nanostructure,electrochemical characteristics and electrocatalytic activity were characterized,and the formation mechanism was investigated.The average particle size was 2.3 nm,the same as that of Pt/C catalyst.The W/Pt atomic ratio was 1/20,much lower than the design of 1/3.The deposition of WO3·xH2O nanoparticles on Vulcan XC-72R carbon black was found to be very difficult by TEM.From XPS and XRD,the Pt nanoparticles were formed in the colloidal solution of Na2WO4,the EG insoluble Na2WO4 resulted in the decreased relative crystallinity and increased crystalline lattice constant compared with those of Pt/C catalyst and,subsequently,the higher specific electrocatalytic activity as determined by CV.The Pt-mass and Pt-electrochemically-active-specific-surface-area based anodic peak current densities for ethanol oxidation were 422.2 mA·mg-1Pt and 0.43 mA·cm-2Pt,1.2 and 1.1 times higher than those of Pt/C catalyst,respectively.     

Two-dimensional PtRu Nanoclusters Carbon Based Electrocatalysts for Methanol Oxidation

A novel method to prepare an electrocatalyst with a new structure and high catalytic performance was reported. Two-dimensional (2D) PtRu nanoclusters have been successfully deposited on graphene oxide and carbon black supports. Compared with the commercial 3D E-TEK PtRu samples, the prepared 2D PtRu composites have larger electrochemically active surface area and display much higher catalytic activity toward methanol oxidation reaction. The preparation method mainly includes the following procedures: oxidation of carbon matrix, Pb²⁺ adsorption on the surface of carbon support, Pb²⁺ electrochemical reduction and galvanic displacement of Pb⁰ by Pt²⁺ and Ru³⁺. The method developed in this study could be viable for solving the problem of low electrocatalytic activity in direct methanol fuel cell anodes.     

Effect of Dy on structure and magnetic properties of DyxFe60.5?xPt39.5 Alloys

Effects of the content of Dy on structure and magnetic properties of Dy _x Fe_60.5−x Pt_39.5 alloys(x=0, 0.5, 1.0, 1.5) were investigated. The results of XRD analysis proved that the phase-transitional temperature of Dy _x Fe_60.5−x Pt_39.5 alloys from disordered face-centered-cubic structure to ordered face-centered-tetragonal cubic structure decreases with the increase of the content of Dy(x). Suitable content of Dy can improve the exchange coupling between soft magnetic phase and hard magnetic phase by refining grain size, while the remanence ratio and coercivity of the Fe_60.5Pt_39.5 alloy can be significantly improved by a small replacement of Fe by Dy, good magnetic properties were obtained in Dy_0.5Fe_60.0Pt_39.5 alloys.     

Influences of melt spinning on electrochemical hydrogen storage performance of nanocrystalline and amorphous Mg2Ni-type alloys

In order to improve the electrochemical hydrogen storage performance of the Mg₂Ni-type electrode alloys, Mg in the alloy was partially substituted by La, and the nanocrystalline and amorphous Mg₂Ni-type Mg_20−x La _x Ni₁₀ (x=0, 2) alloys were synthesized by melt-spinning technique. The microstructures of the as-spun alloys were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical hydrogen storage properties of the experimental alloys were tested. The results show that no amorphous phase is detected in the as-spun Mg₂₀Ni₁₀ alloy, but the as-spun Mg₁₈La₂Ni₁₀ alloy holds a major amorphous phase. As La content increases from 0 to 2, the maximum discharge capacity of the as-spun (20 m/s) alloys rises from 96.5 to 387.1 mA·h/g, and the capacity retaining rate (S ₂₀) at the 20th cycle grows from 31.3% to 71.7%. Melt-spinning engenders an impactful effect on the electrochemical hydrogen storage performances of the alloys. With the increase in the spinning rate from 0 to 30 m/s, the maximum discharge capacity increases from 30.3 to 135.5 mA·h/g for the Mg₂₀Ni₁₀ alloy, and from 197.2 to 406.5 mA·h/g for the Mg₁₈La₂Ni₁₀ alloy. The capacity retaining rate (S ₂₀) of the Mg₂₀Ni₁₀ alloy at the 20th cycle slightly falls from 36.7% to 27.1%, but it markedly mounts up from 37.3% to 78.3% for the Mg₁₈La₂Ni₁₀ alloy.     

Structural evolution and stability of mechanically alloyed Fe-Ni nanocrystalline

The structural evolution and stability of Fe100-xNix(x=10, 20, 35, 50) alloys prepared by mechanical alloying were investigated through X-ray diffraction analysis and transmission electron microscopy. The intrinsic conditions of preparation determining phase stability in nanocrystalline were clarified. After being milled for 120 h, the powders of Fe90Ni10 and Fe80Ni20 consist of a single α(bcc) phase, Fe30Ni30 powders are a single γ(fcc), and for Fe65Ni35 powders there is co-existence of α and γ phases. The as-milled Fe80Ni20 powders annealed at 680 ℃ exhibits the stability of high-temperature γ phase at room temperature, which is consistent with the theoretical prediction.     

Synthesis of Ni-Zn ferrite and its microstructure and magnetic properties

1 INTRODUCTION Ni-Zn ferrite with spinel structure is a versatile technological material due to their high-resistivity and low-eddy current losses, particularly suitable for high-frequency applications. Ni-Zn ferrites have been commercially used in recording heads, antennas rods, loading coils, microwave devices and telecommunication applications fields, and so on[1?2]. Ni-Zn ferrites are usually prepared by the conventional ceramic method[3] and the wet-chemical method[4?16]. The cerami…     

Simulation of the precipitation process of Ni75AixV25-x alloys incorporated in the microelasticity field

The microelasticity field was incorporated into the microscopic phase-field equation for the ternary alloy systems, the morphology evolution and coarsening behavior of the Ni75AixV25-x alloy were simulated. The γ phase precipitates initially for Ni75Al7aV17.9 and Ni75Al5.5V19.5 alloys and the two phases transform from the equiaxed or strip-like to the quadrate as the growth and coarsening processes. For the anisotropic elasticity interaction of the system, the orientation of γ is along the 〈001〉 directions and the θ phase is along the short axis direction of [10]. Analysis of the structure and the pair-correlation functions indicate that the average precipitate length scale of the particles increases at the late-stage coarsening, and the dynamical scaling behavior is obeyed.