Crystalline mesoporous metal oxide

Since the discovery of many types of mesoporous silicas, such as SBA-15, KIT-6, FDU-12 and SBA-16, porous crystalline transition metal oxides, such as Cr2O3, Co3O4, In2O3, NiO, CeO2, WO3, Fe2O3 and MnO2, have been synthesized using the mesoporous silicas as hard templates. Several synthetic methods have been developed. These new porous materials have high potential applications in catalysis, Li-ion rechargeable batteries and gas sensors. This article gives a brief review of the research of porous crystals of metal oxides in the last four years.     

基于孔隙度分类的超维重建算法

由于超维算法在字典建立过程和三维重建过程都涉及到大量的模式匹配,导致超维算法耗时较长,在实际的应用中还有一定难度.针对这个问题,本文提出了一种基于孔隙度分类的超维重建算法,能够较大程度上减少三维重建的时间成本.首先,结合字典元素的孔隙度这一特征对字典集进行分类;其次,利用孔隙度分类字典在重建时采取依孔隙度的搜索方式,优先搜索相应的字典区间;然后,针对不同的训练图像进行三维重建,结合孔隙度分布,提出了一种自适应的搜索范围确定方法;最后,通过对高中低三种孔隙度的训练图像分别进行多次重建,将传统超维算法和新算法的重建结果与真实岩心三维结构的统计特征函数、孔隙参数以及两种算法重建时间的进行对比分析,验证算法的有效性.     

声波在固体-多孔媒质界面上的反射和折射

本文介绍了流体饱和的多孔媒质中声波传播特性,较详细地讨论了声波从各向同性固体入射到多孔媒质界面时反射波、折射波势函数与入射波势函数的振幅比,计算了各种波所携带的声功率在入射波声功率中所占比例.本文的数值计算虽然限於高频,但所提出的方法可应用於任何频率的声波.     

底部加热多孔介质内传热数值研究

为了研究底部加热多孔介质方腔内的自然对流传热,采用整体求解法对方腔内的温度场和流场进行了数值模拟计算,着重分析了瑞利数Ra对多孔介质方腔内自然对流换热特性的影响.计算结果表明:随着Ra数的逐渐增加,对流换热开始占主要作用,等温线变得扭曲;流线由逆时针单胞对流逐渐变化为正反两个双胞对流,流动出现分叉现象,温度场和流线相互对应.平均Nusselt也随之增大,换热效果得到增强.     

MnO2电极双传输线模型和交流阻抗法

MnO_2电极是由宏孔和微孔组成的多孔电极,为了描述多孔性质建立了双传输线数学模型,并给出电极阻抗和界面电位分布函数的计算方法,还设计出一种模拟电池,并通过交流阻抗实验确定了双传输线参量,讨论了MnO_2电极利用均一性同题。     

ASP三元复合体系在孔隙介质中的流变性

利用室内物理模拟的方法,对三元复合体系在多孔介质中的流变行为进行了研究,分析了聚合物、碱、表面活性剂浓度和岩芯渗透率对三元复合体系在多孔介质中的流变特征的影响规律,研究结果认为复合体系在多孔介质中呈现出剪切变稀和增稠双重流变特性,复合体系在多孔介质中出现粘弹流变特征的临界剪切速率随着聚合物浓度的升高而减小,随着表面活性剂和碱浓度的增加而增大。     

电化学脉冲腐蚀制备均匀发光多孔硅

采用脉冲腐蚀和直流电化学腐蚀两种方法制备多孔硅,对这两种方法制备的多孔硅样品进行了扫描电镜和荧光光谱测量,发现脉冲腐蚀制备的多孔硅样品比直流腐蚀制备的多孔硅样品表面均匀、硅丝或者硅柱的尺寸较小、发光强度大,而且发光峰位有明显.的蓝移现象.同时我们还发现多孔硅样品的尺寸越小其能带越宽,由此得出多孔硅样品的发光现象符合量子限域解释的多孔硅的发光机制.     

Sodium-ion capacitors with superior energy-power performance by using carbon-based materials in both electrodes

Na-ion capacitors(NICs) are promising energy storage devices in virtue of their merits in combining the high energy densities of secondary batteries and the high power densities of supercapacitors.However,it is still very challenging to achieve a balanced energy-power performance in NIC device due to the kinetic imbalance between the battery-type anode and the capacitive-type cathode.In this work,an NIC device based on carbon materials for both anode and cathode has been reported.As-prepared(polyimide/graphene oxide)-derived carbon(PIGC) anode material shows excellent rate capability,which can deliver a specific capacity of 110 mAh g~(-1) at high current densities of 5 A g~(-1).In addition,the N,B co-doped expanded reduced graphite oxide(NBEG)cathode demonstrates a high specific capacitance of 328 F g~(-1).Due to the improved rate capability of PIGC anode and specific capacitance of NBEG cathode,the imbalance on the energy and power densities between anode and cathode is well addressed.As-assembled PIGC//NBEG device can deliver an energy density of 55 W h kg~(-1) even at a high power density of 9500 W kg~(-1).The energy-power properties of PIGC//NBEG are superior to many state-of-the-art NIC devices that using carbon or non-carbon based electrodes.This work offers not only a promising device configuration with superior energy-power properties,but also a guidance for the design strategies on electrode materials for high-throughput energy storage systems.     

寒区冻土层含冰孔隙结构导热模型构建及应用分析

冻土主要由固、液和气三相物质构成,其中固体可以看成骨架,另外两相物质填充在孔隙中,是典型的多孔介质。寒区冻土层融沉过程中,其中的孔隙结构、矿物颗粒和含冰量等参数变化幅度较大,导热系数等热物性参数随之变化,目前在精细表征和分析研究方面存在一定不足。针对含冰冻土,采用多孔介质描述方法,考虑其相态变化特性,将其分为未冻区、融化区、固结区及已冻区;基于表征单元体(representative elementary volume, REV)方法,结合冻土物理学和传热传质学理论,构建了冻土层导热分析模型,包括微观模型和宏观分析模型;以寒区土壤冻融过程为例进行模拟计算,分析了孔隙率、含水率、含冰率以及通道构成系数等对冻土导热系数的影响规律。所建模型可为寒区冻土传热机理分析及导热特性研究提供理论基础。     

盐酸浓度对多孔中空棒状In_2O_3结构的影响

用化学腐蚀的方法把ZnO/In_2O_3核壳结构中的ZnO纳米棒除去形成多孔中空棒状的In_2O_3纳米结构,探讨化学腐蚀中ZnO核恰好完全去除,且壳层In_2O_3中空形貌不被破坏时HCl的最佳浓度。采用X射线衍射、扫描电镜、透射电镜对产物的物相、微观形貌进行表征。结果表明:pH=1的HCl既可保证ZnO完全去除,又不影响In_2O_3多孔中空形貌。