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多级孔硅铝材料因优异的性能而成为金属催化剂的重要载体。研究采用水热法以硝酸铝为铝源、正硅酸乙酯(TEOS)为硅源合成了Al掺杂SiO2(Al-SiO2)的多级孔材料, 然后采用等体积浸渍法负载钴, 制备了具有多级孔结构的 Co/Al-SiO2催化剂。对Al-SiO2材料的表征结果表明: 以四丙基氢氧化铵(TPAOH)为结构导向剂, 经80 ℃水热处理可以合成多级孔Al-SiO2, 呈尺寸在30~40 nm范围的 “蠕虫状”大孔分布形态。将催化剂用于费-托合成反应, 与商业SiO2负载的钴催化剂相比, Co/Al-SiO2的CO转化率提高近一倍, CH4选择性降低19.3wt%, C2-C4选择性降低13.3wt%, 汽油段产物(C5-C12)选择性达到53.3wt%。 相似文献
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《Journal of Experimental Nanoscience》2013,8(4):294-301
Indium hydroxide nanostructures were synthesised by sol-gel and hydrothermal processes from indium acetate and sodium hydroxide as precursors and polyvinyl alcohol, polyvinyl pyrrolidone or polydimethylsiloxane as stabilisers. Calcination of the In(OH)3 nanostructures at 500°C in air yielded In2O3 nanoparticles. The morphology, crystallinity and thermal behaviour of the obtained products of each method were investigated by X-ray diffraction, scanning electron microscopy and thermal gravimetry analysis and differential thermal analysis. 相似文献
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采用超声波辅助沉淀法分别在单元掺杂、二元掺杂和不掺杂三种情况下制备了三种不同镍源的纳米氢氧化镍,研究三种阴离子(NO3-,Cl-,SO2-4)对产物晶相结构及稳定性的影响。结果表明:未掺杂时,半径较大的SO2-4离子有利于α‐Ni(OH)2的形成;在单掺杂Co(Ni2+∶Co2+=1∶0.20)时,NO3-离子不仅有利于α‐Ni(OH)2的形成,而且可以使α‐Ni(OH)2在碱液中保持较高的稳定性;当复合掺杂Co/Cu(Ni2+∶Co2+∶Cu2+=1∶0.15∶0.05)时,三种镍源制得的样品均为纯α‐Ni(OH)2结构,但以Ni(NO3)2为镍源的α‐Ni(OH)2在碱液中结构稳定性较高,NiCl2次之,NiSO4较差。可见,α‐Ni(OH)2结构及稳定性既与掺杂情况有关,也与阴离子密切相关。 相似文献
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采用燃烧法合成纳米La(OH)3材料,分别以硝酸镧和柠檬酸为镧源和络合剂,以氨水调节pH值为2~4、柠檬酸与硝酸镧的物质的量比为1~1.2∶1之间,加热凝胶至自蔓延燃烧后并在700~750℃煅烧1~2 h,得到膨松粉末状产物,即La2O3纳米晶。利用X射线衍射和透射电镜等测试方法对凝胶热分解过程及最终形成的La2O3纳米晶颗粒进行分析和表征。结果表明:用该方法得到的纳米La2O3产物的平均粒径在30~100 nm之间可控;纳米La2O3在空气中是不稳定的,在自然吸潮情况下和空气中的H2O发生反应生成La(OH)3,控制湿度即可得到纯La(OH)3纳米晶。 相似文献
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以硝酸铜、钼酸钠及氢氧化钠为原料,采用简单的水相沉淀法,在60℃下合成出钼铜矿(Cu3(MoO4)2(OH)2).通过X射线衍射、扫描电镜、透射电镜、热重与差热分析、红外光谱及荧光光谱等测试手段对材料的微观结构、形貌、热稳定性及谱学特性进行表征分析.结果显示,制备的产物为结晶性良好的、至少一维是纳米的片状结构材料,属于单斜型(晶胞参数a=0.53863 nm,b=1.40006 nm,c=0.56003 nm),其元素摩尔含量比约为3:2:10,与推测的分子式完全吻合.热重与差热分析数据表明Cu3(MoO4)2(OH)2纳米晶具有很好的热稳定性且起始分解温度为320℃.通过软件测得的d(021)面与d(ī21)面的晶间面距分别为0.435 nm与0.358 nm,与理论值基本相符.经测量,Cu3(MoO4)2(OH)2纳米晶具有强的荧光性质,在激发波长369 nm的作用下在530 nm表现为强发射峰.此外,还探讨了Cu3(MoO4)2(OH)2纳米晶的形成机理. 相似文献
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Formation of Septuple‐Shelled (Co2/3Mn1/3)(Co5/6Mn1/6)2O4 Hollow Spheres as Electrode Material for Alkaline Rechargeable Battery
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Xiaoxian Zhao Ranbo Yu Hongjie Tang Dan Mao Jian Qi Bao Wang Yu Zhang Huijun Zhao Wenping Hu Dan Wang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(34)
The multishelled (Co2/3Mn1/3)(Co5/6Mn1/6)2O4 hollow microspheres with controllable shell numbers up to septuple shells are synthesized using developed sequential templating method. Exhilaratingly, the septuple‐shelled complex metal oxide hollow microsphere is synthesized for the first time by doping Mn into Co3O4, leading to the change of crystalline rate of precursor. Used as electrode materials for alkaline rechargeable battery, it shows a remarkable reversible capacity (236.39 mAh g?1 at a current density of 1 A g?1 by three‐electrode system and 106.85 mAh g?1 at 0.5 A g?1 in alkaline battery) and excellent cycling performance due to its unique structure. 相似文献
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利用低放热Al-TiO2反应体系部分取代高放热Al-CoO反应体系,并加入适量的稀释剂Al2O3吸收反应热量,通过热爆燃烧合成结合致密化工艺制备了铁磁性Co(Ti)-Al2O3金属陶瓷。研究表明,Co(Ti)-Al2O3金属陶瓷中随着Al-TiO2体系的增加,燃烧反应温度降低,金属相尺寸减小,分布更均匀,同时在金属相与基体之间形成过渡区域,提高了界面结合。Co(Ti)-Al2O3复合材料的饱和磁化强度随着金属Co含量增加而增加,最高可达到37.2849Am2/kg,而矫顽力在3997.6~5615.4A/m范围内变化,介于软磁体和硬磁体之间。 相似文献
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Xin Shi Julian Key Shan Ji Vladimir Linkov Fusheng Liu Hui Wang Hengjun Gai Rongfang Wang 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(29)
Porous Ni(OH)2 nanoflakes are directly grown on the surface of nickel foam supported Ni3Se2 nanowire arrays using an in situ growth procedure to form 3D Ni3Se2@Ni(OH)2 hybrid material. Owing to good conductivity of Ni3Se2, high specific capacitance of Ni(OH)2 and its unique architecture, the obtained Ni3Se2@Ni(OH)2 exhibits a high specific capacitance of 1689 µAh cm?2 (281.5 mAh g?1) at a discharge current of 3 mA cm?2 and a superior rate capability. Both the high energy density of 59.47 Wh kg?1 at a power density of 100.54 W kg?1 and remarkable cycling stability with only a 16.4% capacity loss after 10 000 cycles are demonstrated in an asymmetric supercapacitor cell comprising Ni3Se2@Ni(OH)2 as a positive electrode and activated carbon as a negative electrode. Furthermore, the cell achieved a high energy density of 50.9 Wh L?1 at a power density of 83.62 W L?1 in combination with an extraordinary coulombic efficiency of 97% and an energy efficiency of 88.36% at 5 mA cm?2 when activated carbon is replaced by metal hydride from a commercial NiMH battery. Excellent electrochemical performance indicates that Ni3Se2@Ni(OH)2 composite can become a promising electrode material for energy storage applications. 相似文献
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Flake-like β-Co(OH)2 with dimension around 20-50 nm was conveniently synthesized via a simple, low cost and practical room-temperature solid-state reaction with the assistance of polyethylene glycol (PEG) 400 and its electrochemical properties were evaluated using cyclic voltammetry (CV) and galvanostatic charge-discharge technology. A high specific capacitance of 658.4 F g− 1 at 5 mA was observed for the β-Co(OH)2 nanoflakes, compared to 302.7 F g− 1 for the block-like β-Co(OH)2 obtained without the PEG-400, showing the morphological function of nanoflakes for improving the capacitive performance. Furthermore, the β-Co(OH)2 nanoflakes can offer a good specific capacitance retention of ca. 80% after 1000 cycles, suggesting its potential application in supercapacitors. 相似文献
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Rechargeable Batteries: Formation of Septuple‐Shelled (Co2/3Mn1/3)(Co5/6Mn1/6)2O4 Hollow Spheres as Electrode Material for Alkaline Rechargeable Battery (Adv. Mater. 34/2017)
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Xiaoxian Zhao Ranbo Yu Hongjie Tang Dan Mao Jian Qi Bao Wang Yu Zhang Huijun Zhao Wenping Hu Dan Wang 《Advanced materials (Deerfield Beach, Fla.)》2017,29(34)
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通过碳辅助法和溶胶-凝胶法制备了具有可见光下光催化制氢性能的TiO2/Co3O4复合纳米颗粒。采用X射线衍射仪(XRD)、透射电子显微镜(TEM)和高分辨率透射电子显微镜(HRTEM), 以及紫外可见分光光度计表征了复合纳米颗粒的晶体结构、微观形貌和紫外-可见光谱吸收能力。结果表明, 制备的复合纳米颗粒具有良好的晶型、结构以及紫外可见光吸收能力。实验测试了TiO2/Co3O4复合纳米颗粒在模拟太阳光下的光催化制氢性能, 并研究了其光催化制氢的可重复利用性。结果表明, 在模拟太阳光照射下, 该复合纳米颗粒催化纯水产生氢气的速率约为8.25 μmol/(g·h), 且该复合纳米颗粒具有良好的可重复利用性。 相似文献
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Highly Stable COF‐Supported Co/Co(OH)2 Nanoparticles Heterogeneous Catalyst for Reduction of Nitrile/Nitro Compounds under Mild Conditions
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Ordered nanoporosity in covalent organic framework (COF) offers excellent opportunity for property development. Loading nanoparticles (nPs) onto them is one approach to introducing tailor‐made properties into a COF. Here, a COF–Co/Co(OH)2 composite containing about 16 wt% of <6 nm sized Co/Co(OH)2 nPs is prepared on a N‐rich COF support that catalyzes the release of theoretical equivalence of H2 from readily available, safe, and cheap NaBH4. Furthermore, the released H2 is utilized for the hydrogenation of nitrile and nitro compounds to amines under ambient conditions in a facile one‐pot reaction. The COF “by choice” is built from “methoxy” functionalized dialdehydes which is crucial in enabling the complete retention of the COF structure under the conditions of the catalysis, where the regular Schiff bonds would have hydrolyzed. The N‐rich binding pockets in the COF ensure strong nP–COF interactions, which provides stability and enables catalyst recycling. Modeling studies reveal the crucial role played by the COF in exposing the active facets and thereby in controlling the activation of the reducing agent. Additionally, via density functional theory, we provide a rational explanation for how these COFs can stabilize nanoparticles which grow beyond the limiting pore size of the COF and yet result in a truly stable heterogeneous catalyst – a ubiquitous observation. The study underscores the versatility of COF as a heterogeneous support for developing cheap and highly active nonnoble metal catalysts. 相似文献
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Yan Yang Qingqin Liang dinghong Li Yuan Zhuang Yunhua He Bo Bai Xun Wang 《Nano Research》2011,4(9):882-890
Highly crystalline and thermally stable pure multi-walled Ni3Si2O5(OH)4 nanotubes with a layered structure have been synthesized in water at a relatively low temperature of 200–210 °C using a facile
and simple method. The nickel ions between the layers could be reduced in situ to form size-tunable Ni nanocrystals, which endowed these nanotubes with tunable magnetic properties. Additionally, when
used as the anode material in a lithium ion battery, the layered structure of the Ni3Si2O5(OH)4 nanotubes provided favorable transport kinetics for lithium ions and the discharge capacity reached 226.7 mA·h·g−1 after 21 cycles at a rate of 20 mA·g−1. Furthermore, after the nanotubes were calcined (600 °C, 4 h) or reduced (180 °C, 10 h), the corresponding discharge capacities
increased to 277.2 mA·h·g−1 and 308.5 mA·h·g−1, respectively.
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Pb(Fe2/3W1/3)O3的制备及其介电性能研究 总被引:1,自引:0,他引:1
本文采用半化学法,即硝酸铁代替传统氧化物混合法中的三氧化二铁与PbO和WO3浆料混合,经850℃,2h预烧,一步合成了钙钛矿单相的Pb(Fe2/3W1/3)O3(PFW)预烧粉体;再经870℃和2h烧结,得到了纯钙钛矿相的PFW陶瓷,其理论密度大于98%,在1kHz时的最大介电常数εmax为8000,高于二次合成法和传统氧化物法制备的PFW陶瓷,表明半化学法对制备PFW陶瓷是可行的. 相似文献
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Heterogenous Catalysts: Highly Stable COF‐Supported Co/Co(OH)2 Nanoparticles Heterogeneous Catalyst for Reduction of Nitrile/Nitro Compounds under Mild Conditions (Small 37/2018)
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Dinesh Mullangi Debanjan Chakraborty Anu Pradeep Vijay Koshti Chathakudath P. Vinod Soumendranath Panja Sunil Nair Ramanathan Vaidhyanathan 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(37)