Cobalt and nitrogen atoms co-doped porous carbon for advanced electrical double-layer capacitors

Electrical double-laye r capacitors are widely concerned fo r their high power density,long cycling life and high cycling efficiency.However,their wide application is limited by their low energy density.In this study,we propose a simple yet environmental friendly method to synthesize cobalt and nitrogen atoms co-doped porous carbon(CoAT-NC) material.Cobalt atoms connected with primarily pyridinic nitrogen atoms can be uniformly dispersed in the amorphous carbon matrix,which is benefit for improving electrical conductivity and density of states of the carbon material.Therefore,an enhanced perfo rmance is expected when CoAT-NC is served as electrode in a supercapacitor device.CoAT-NC displays a good gravimetric capacitance of 160 F/g at 0.5 A/g combing with outstanding capacitance retention of 90% at an extremely high current density of 100 A/g in acid electrolyte.Furthermore,a good energy density of30 Wh/kg can be obtained in the organic electrolyte.     

Effect of the Cu co-activator on the charge-carrier trapping efficiency in CaSO4:Tm,Cu

Rare earth doped CaSO₄ materials are well known thermoluminescent dosimeters with friendly properties. They are used in the practice for a long while. New phosphors based on CaSO₄:Tm were synthesized using a modified preparation method for adding Cu as co-dopant. The produced materials have several favorable new characteristics. Larger linear dose response range, simpler glow-curve structure and a small diminution in the sensitivity are the consequences of the copper addition. Trapping efficiency of samples containing different amounts of Tm and Cu was investigated as the function of the composition using a consecutive RL/TL measuring technique. It was cleared up that the Cu addition, depending on its amount, reduced this value. This plays the main role in the sensitivity loss and forms one of the factors in the explanation of the linear dose range widening.     

Synthesis and characterization of LiCo<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Mn<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript>O<Subscript>4</Subscript> powder by a novel CAM microwave-assisted sol–gel method for Li ion battery

LiMn₂O₄-based spinels are of great interest as positive electrode materials for lithium ion batteries. LiCo _x Mn_2−x O₄ (x = 0.0, 0.1, 0.2, 0.3, and 0.4) spinel phases have been synthesized by novel citric acid-modified microwave-assisted sol–gel method. The structural properties of the synthesized products have been investigated by X-ray powder diffraction and scanning electron microscopy. To improve the recharge capacity of Li/LiCo _x Mn_2−x O₄ cells, the electrochemical features of LiCo _x Mn_2−x O₄ compounds have been evaluated as positive electrode materials. The structural properties of Co-doped oxides are very similar to LiMn₂O₄ electrode. Techniques like cyclic voltammetry, charge–discharge and cycle life are also used to characterize the LiCo _x Mn_2−x O₄ (x = 0.0, 0.1, 0.2, 0.3, and 0.4) electrodes.     

白光LED用新型Ce,Pr掺杂的YAG单晶荧光材料的光谱性能研究

为了改善白光LED用荧光材料效率低、均匀性差、光衰大、寿命短及物化性能差等不足,本文采用单晶荧光材料取代荧光粉来制备白光LED,并对白光LED用新型YAG单晶荧光材料的制备和光谱性能进行了研究.采用提拉法生长了白光LED用Ce∶YAG及Pr,Ce∶YAG晶体,并通过吸收光谱,激发、发射光谱对晶体材料的光谱特性进行表征.研究表明,Ce∶YAG单晶荧光材料可以被发射波长460 nm左右的蓝光芯片有效激发,产生一个范围为480~650 nm宽峰发射.通过Pr3+,Ce3+离子共掺杂可以有效补偿Ce3+离子单掺杂YAG荧光材料发光中的红色发光成分.     

Density functional theory study of formaldehyde adsorption and decomposition on Co-doped defective CeO_2(110) surface

Formaldehyde as an air pollutant to adverse health effects for humanity has been getting attention. The adsorption and dissociation of formaldehyde(HCHO) on the Co_xCe_(1-x_O_(2-δ)(110) surface were investigated by the density functional theory(DFT) calculations. We calculated the oxygen vacancy formation energy as the function of its site around dopant Co in detail. The results showed that Co doping was accompanied by compensating oxygen hole spontaneous formation.The adsorption configurations and bindings of HCHO at different locations on the Co_xCe_(1-x)O_2(110) were presented.Four possible pathways of oxidation of formaldehyde on the catalytic surface were explored. The results suggested that formaldehyde dissociation at different adsorption sites on the doped CeO_2(110) — first forming dioxymethylene(CH_2O_2)intermediate, and then decomposing into H_2O, H_2, CO_2, and CO molecules. It was found that the presence of cobalt and oxygen vacancy significantly prompted the surface activity of CeO_2.     

Enhanced photocatalytic activity and stability of nano-scaled TiO2 co-doped with N and Fe

Titanium dioxide (TiO₂) nanoparticles co-doped with N and Fe were prepared via modified sol-gel process. The products were characterized by transmission electron microscopy (TEM), N₂ adsorption, X-ray diffraction (XRD), Raman spectroscopy, UV-vis spectroscopy, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). It is shown that the prepared TiO₂ particles were less than 10 nm with narrow particle size distribution. The addition of MCM-41 caused the formation of Ti-O-Si bond which fixed the TiO₂ on MCM-41 surface, thus restricted the agglomeration and growth of TiO₂ particles. The photocatalytic performance in the degradation of methylene blue showed that N, Fe co-doped TiO₂ exhibited much higher photocatalytic activity than doped sample with nitrogen or Fe³⁺ alone under both UV and visible light. N, Fe co-doping decreased the loss of doping N during the degradation reaction, thus increased the photocatalytic stability. It was also found that the nitridation time had significant influence on the photocatalytic activity of prepared TiO₂ catalysts.     

Y2O3 and MgO co-doped ceria based electrolytes

Electrolytes of Ce_1-x-y Y _x Mg _y O_2-0.5x-y were prepared with citrate method and were characterized by inductively coupled plasma-atomic emission spectrometry, energy dispersive spectrometry, powder X-ray diffraction, and impedance spectroscopy. The effect of composition on the structure, conductivity, and stability of the electrolytes were investigated. When 0≤x≤ about 0.2 and 0≤y≤ about 0.05, the electrolytes were all single phase materials of ceria-based solid solution. However, when y> about 0.05, the electrolytes became two-phase materials, Y³⁺ and Mg²⁺ co-doped ceria-based solid solution and free MgO. The sample with nominal composition of Ce_0.815Y_0.065Mg_0.12O_2-d showed ionic conductivity at 973 K close to or even a little higher than that of similarly prepared Ce_0.9Gd_0.1O_1.95, but had lower cost of raw materials and a little better stability in reducing atmosphere. The existing of free MgO improved the stability of the electrolytes in reducing atmosphere, but too much free MgO reduced the conductivity.     

Co掺杂量对Ti1-xCoxO2纳米颗粒结构及磁性的影响

以钛酸丁酯、六水硝酸钴等为原料,采用溶胶凝胶法合成Ti1-xCoxO2干凝胶前驱体,将前驱体在500℃空气氛围下进行退火处理,得到一系列Ti1-xCoxO2纳米颗粒样品.采用差热/热重综合热分析仪(TG-DTA)、X射线衍射仪(XRD)、拉曼光谱(Raman)和振动样品磁场计(VSM)对样品的结构和磁性进行研究.结果表...     

选区激光熔化及热处理工艺对钴铬合金力学性能的影响

系统研究了选区激光熔化（SLM）及热处理工艺对钴铬合金组织与性能的影响。通过设计正交实验,利用EOS M290选区激光熔化设备,优化钴铬合金成型的工艺参数;利用XRD、扫描电镜（SEM）、硬度仪及万能材料试验机对选区激光熔化钴铬合金的显微组织结构、物相组成及力学性能进行观察与测试。研究结果表明,选区激光熔化成型的最佳工艺参数为：扫描间距0.08 mm,扫描速度1110 mm/s,激光功率335 W,能量密度4.8 J/mm2,获得的致密度高达99.18%,且最佳的填充角度为67。SLM成型的钴铬合金的物相主要由相及少量相共存,微观组织由细小均匀的胞状晶及柱状晶构成;其硬度、抗拉强度及延伸率分别为41.0HRC,1032 MPa,10%,断裂机制主要为穿晶脆性断裂。热处理后显微组织发生相变,主要为相及少量相,并产生少量强化相M23C6(M=Cr,Mo,W);其硬度、抗拉强度及延伸率分别提升了6.1%,35.9%和17.6%,断裂机制主要为准解理断裂。     

双卤化物共掺新型硫系多光谱玻璃的制备及性能

利用传统熔融-淬冷工艺制备了65GeS_2-15Ga_2S_3-(20-x)CsCl-xCsI(x=0,5,10,15,20)系列硫卤玻璃;通过测试该系列玻璃样品的密度、显微硬度、可见/近红外吸收光谱、红外透射光谱、喇曼谱、XRD衍射谱、玻璃转变温度等,对其进行了系统研究.结果表明:该系列玻璃具有较宽的成玻范围,在0.42~12μm范围内具有良好的透过率;随着CsI含量(mol%)的增加,玻璃的密度逐渐增大;随着CsCl含量(mol%)的增加,光学带隙以及硬度逐渐增大;玻璃样品的玻璃转变温度随Cl~-、I~-的共掺比例发生明显变化,当Cl~-(mol%):I-(mol%)=1时,玻璃转变温度最低.