Er3+单掺、Er3+/Yb3+共掺杂Ca12Al14O32F2的 制备及上转换发光性质

利用高温固相法成功制备了Er~(3+)单掺、Er~(3+)/Yb~(3+)共掺杂Ca_(12)Al_(14)O_(32)F_2上转换发光样品。在980 nm激光激发下,Er~(3+)单掺和Er~(3+)/Yb~(3+)共掺杂样品均呈现出较强的绿光(528,549 nm)和较弱的红光(655 nm)发射,分别归因于Er~(3+)离子的~2H_(11/2),~4S_(3/2)→~4I_(15/2)和~4F_(9/2)→~4I_(15/2)能级跃迁。随着Er离子浓度的增加,单掺杂样品上转换发光强度先增大后减小,最佳掺杂浓度为0.8%。共掺杂Yb~(3+)后,Er~(3+)的发光强度明显增大。还原气氛下合成的样品上转换发光强度增大约两倍,可能和笼中阴离子基团变化有关。发光强度和激发光功率的关系表明所得上转换发射为双光子吸收过程,借助Er~(3+)-Yb~(3+)体系能级结构详细讨论了上转换发射的跃迁机制。     

Study on the mechanism of catalytic synthesis of dimethyldichlorosilane by AlCl3/MIL‐53(Al)@γ‐Al2O3

Dimethyldichlorosilane, one of the most consumed organosilicon monomers in the industry, can be prepared in a highly efficient and environmentally friendly synthesis method of disproportionating methylchlorosilanes. However, the internal mechanism of the reaction remains unclear. In this paper, the mechanism catalyzed by AlCl₃/MIL‐53(Al) and AlCl₃/MIL‐53(Al)@γ‐Al₂O₃ catalysts was calculated at B3LYP/6‐311++G(3df, 2pd) level by using the density functional theory (DFT). The results showed that although the two catalysts had similar active structures, the catalytic effects were significantly different. The Lewis acid center on the surface of γ‐Al₂O₃ in the core‐shell catalyst is complementary to the classic Lewis acid AlCl₃ through the spatial superposition effect, which greatly improves the Lewis acid catalytic activity of AlCl₃/MIL‐53(Al)@γ‐Al₂O₃.     

Surface passivation in n-type silicon and its application in silicon drift detector

Based on the surface passivation of n-type silicon in a silicon drift detector(SDD), we propose a new passivation structure of SiO2/Al2O3/SiO2 passivation stacks. Since the SiO2 formed by the nitric-acid-oxidation-of-silicon(NAOS)method has good compactness and simple process, the first layer film is formed by the NAOS method. The Al2O3 film is also introduced into the passivation stacks owing to exceptional advantages such as good interface characteristic and simple process. In addition, for requirements of thickness and deposition temperature, the third layer of the SiO2 film is deposited by plasma enhanced chemical vapor deposition(PECVD). The deposition of the SiO2 film by PECVD is a low-temperature process and has a high deposition rate, which causes little damage to the device and makes the SiO2 film very suitable for serving as the third passivation layer. The passivation approach of stacks can saturate dangling bonds at the interface between stacks and the silicon substrate, and provide positive charge to optimize the field passivation of the n-type substrate.The passivation method ultimately achieves a good combination of chemical and field passivations. Experimental results show that with the passivation structure of SiO2/Al2O3/SiO2, the final minority carrier lifetime reaches 5223 μs at injection of 5×10¹⁵ cm^-3. When it is applied to the passivation of SDD, the leakage current is reduced to the order of nA.     

Facile synthesis,characterization, and decolorization activity of Mn2+ and Al3+ co-doped hexagonal-like ZnO nanostructures as photocatalysts

A good photocatalyst with high efficiency can be synthesized easily using eco-friendly materials and processes. Our synthesized samples exhibit all of the aforementioned features. In this work, manganese co-doped ZnO at different weight percentages (3, 6, 9, and 15 wt.%) with and without 1.5 wt.% aluminum was synthesized by hydrothermal method, and their photocatalytic activity in aqueous solutions of methyl orange (MO) was investigated under visible light. The structural and optical properties of the samples were characterized using X-ray powder diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and diffuse reflectance spectroscopy. In this work, Mn²⁺ ions in the 9%Mn/ZnO sample and Mn²⁺, Al³⁺ ions in the (9%Mn, 1.5%Al)/ZnO sample calcined at 800 °C were replaced instead with some Zn²⁺ ions in hexagonal wurtzite structures of ZnO. These structures were found next to each other in the form of a hexagonal shape that created 3D-hexagonal-like ZnO nanostructures. Finally, nanoparticles (NPs) and nano hexagonal-like ZnO nanostructures were, respectively, dispersed on the surface of 3D-hexagonal-like structure of 9%Mn/ZnO and (9%Mn, 1.5%Al)/ZnO. Diffuse reflectance spectroscopy analysis showed that the (9%Mn, 1.5%Al)/ZnO sample had more light absorption than 9%Mn/ZnO. However, contrary to our expectations, the 9%Mn/ZnO sample had better decolorization efficiency (94%) after 60 min under visible light, which could be attributed to a significant increase in the level of recombination by the aluminum ions.     

固体核磁共振结合密度泛函理论计算研究SSZ-39分子筛的钠离子落位与铝分布

具有AEI结构的SSZ-39分子筛的骨架外阳离子落位和铝分布对其催化性能影响显著.AEI笼中有三个结晶学不等价位，且铝取代T位具有一定的倾向性.本文结合固体核磁共振（NMR）技术（²⁷Al/²³Na MQ MAS NMR），以及密度泛函理论（DFT）计算，研究了不同硅铝比Na-SSZ-39分子筛中的Na⁺落位和铝分布.在孤立铝分布的情况下，铝原子优先占据于T3位，Na⁺主要落位于AEI笼中的SIIa0和SIII'a0位点上，其中SIII'a0位点的优先度较高，此外少部分Na⁺还落位于六棱柱内部的SIa0.当铝对存在时，AlSiSiAl分布的铝对占据六元环的对位（T3-T3），对应的Na⁺分别落位于SIIa1和SⅢ'a1位点.随着分子筛结构的部分破坏，游离的Na⁺可能形成明显的SIII'b位点.本文可加深对SSZ-39分子筛构效关系的理解，为更好地调控催化性能奠定基础.     

凝胶渗透色谱-气相色谱-离子阱质谱法测定桔梗原药和当归提取物中101种农药残留

建立了凝胶渗透色谱（GPC）-气相色谱-离子阱质谱同时检测桔梗原药和当归提取物中101种农药残留的分析方法。方法采用乙腈超声辅助提取桔梗原药和当归提取物,浓缩提取液至近干后用乙酸乙酯-环己烷（1∶1, v/v）复溶,采用凝胶渗透色谱法（选取40 cm长、内径20 mm的凝胶渗透色谱柱）对样品进行净化,弃去前段含脂类、色素等杂质的流出液,收集17~30 min洗脱液并旋转蒸发浓缩至近干,甲苯1 mL定容上机。选用DB-5MS毛细管色谱柱分离待测物,通过离子阱质谱实现对101种农药残留的高效检测。方法通过优化前处理条件和离子阱二级质谱参数,有效降低了复杂中药基质对待测化合物的干扰,最大限度提高了样品中农药的定量准确性和回收率,101种农药3水平添加的平均回收率为58.3%~108.9%,每个添加水平10次独立重复测定的相对标准偏差为0.4%~16.5%,检出限（LOD）范围为0.2~40.0 μg/kg,可满足当前韩国、日本、欧洲规定的最大残留限量（maximum residue limits, MRLs）要求。方法具有操作简单快速、灵敏度高、重复性好等特点,凝胶渗透色谱技术的应用克服了固相萃取小柱净化容量不足的弊端,离子阱技术的应用可以进一步排除共流出基体杂质的干扰,提高定量和定性的准确性,检测效果优于常用的气相色谱-质谱法,是对中药中同时分析多种农药残留检测方法的有益补充。     

Manipulating OH−-Mediated Anode-Cathode Cross-Communication Toward Long-Life Aqueous Zinc-Vanadium Batteries

The anode-cathode interplay is an important but rarely considered factor that initiates the degradation of aqueous zinc ion batteries (AZIBs). Herein, to address the limited cyclability issue of V-based AZIBs, Al₂(SO₄)₃ is proposed as decent electrolyte additive to manipulate OH⁻-mediated cross-communication between Zn anode and NaV₃O₈ ⋅ 1.5H₂O (NVO) cathode. The hydrolysis of Al³⁺ creates a pH≈0.9 strong acidic environment, which unexpectedly prolongs the anode lifespan from 200 to 1000 h. Such impressive improvement is assigned to the alleviation of interfacial OH⁻ accumulation by Al³⁺ adsorption and solid electrolyte interphase formation. Accordingly, the strongly acidified electrolyte, associated with the sedated crossover of anodic OH⁻ toward NVO, remarkably mitigate its undesired dissolution and phase transition. The interrupted OH⁻-mediated communication between the two electrodes endows Zn||NVO batteries with superb cycling stability, at both low and high scan rates.     

双波长双指示剂催化动力学光度法测定痕量Fe(Ⅲ)

研究了在HCl介质中,Fe(Ⅲ)催化H2O2氧化甲基橙和亚甲基蓝褪色的指示反应。通过测量510nm和660nm波长处催化和非催化体系吸光度的变化,基于Fe(Ⅲ)的浓度与两波长处吸光度差值的加和呈线性关系,建立了双波长双指示剂催化动力学光度法测定Fe(Ⅲ)含量的新方法。方法的线性范围为0.008~0.24μg/mL,用该法测定菠菜、紫菜、蛋黄中Fe(Ⅲ)含量,相对标准偏差为1.0%~4.6%,加标回收率为98.9%~104.6%。     

具有双螺旋链结构的3-吡啶丙烯酸镝配合物的水热合成及晶体结构

采用水热法制备了一种新型稀土配位聚合物[Dy(3-PA)3(H2O)]n(3-PA=3-吡啶丙烯酸)(1),并通过X射线单晶衍射结构分析、元素分析、红外光谱、热重分析对配合物1进行了结构表征.结构分析表明,标题配合物属于三斜晶系,Pī空间群,晶胞参数为:a=0.617 16(5)nm,b=1.270 45(11)nm,c=1.564 03(13)nm,α=111.557 0(10)°,β=90.307 0(10)°,γ=95.342 0(10)°,V=1.134 54(16)nm3,Z=2.金属离子Dy(III)通过配体3-AP羧基的桥联作用,链接成为一维双螺旋链状配位聚合物.     

X射线荧光光谱法快速测定铜基催化剂中金属含量

本文使用X射线荧光光谱仪,采用人工制备标样,以粉末直接压片和经验系数校正基体效应的方法,建立了铜基催化剂中CuO、ZnO和Al2O3含量的快速测定方法。考察了样品厚度的影响及方法的精密度和准确度。该法待测元素线性范围较宽,分别为:CuO:13.0%~97.0%,ZnO:0~63.0%,Al2O3:0~25.0%,且相关系数均大于0.99。测定各元素的相对标准偏差均小于0.3%,且测定结果与化学滴定分析结果吻合。该方法快速、简便,可应用于工业生产质量监控。