Fabrication and gas sensing property of honeycomb-like ZnO

We report the structural characterization and proposed formation mechanism of honeycomb-like ZnO conglomerations fabricated by direct precipitation method. X-ray diffraction （XRD）, energy-disperse X-ray spectrometry （EDS）, scanning electron microscopy （SEM） showed that the as-prepared ZnO calcined at 700 ℃ were micron sphere particles with honeycomb-like structure. In the UV-vis absorbing spectrum, it was observed that there is a new additional absorption band at 260 nm, and it was speculated that the absorption may be caused by defects on the surface and interface of honeycomb-like ZnO. The as-products showed high sensitivity and short response time to sulfured hydrogen gas. These results demonstrate that honeycomb-like ZnO conglomerations are very promising materials for fabricating H2S gas sensors.

Crashworthiness of innovative hexagonal honeycomb-like structures subjected to out-of-plane compression

Seeking for innovative structures with higher mechanical performance is a continuous target in railway vehicle crashworthiness design.In the present study,three types of hexagonal reinforced honeycomb-like structures were developed and analyzed subjected to out-of-plane compression,namely triangular honeycomb(TH),double honeycomb(DH)and full inside honeycomb(FH).Theoretical formulas of average force and specific energy absorption(SEA)were constructed based on the energy minimization principle.To validate,corresponding numerical simulations were carried out by explicit finite element method.Good agreement has been observed between them.The results show that all these honeycomb-like structures maintain the same collapsed stages as conventional honeycomb;cell reinforcement can significantly promote the performance,both in the average force and SEA;full inside honeycomb performs better than the general,triangular and double schemes in average force;meanwhile,its SEA is close to that of double scheme;toroidal surface can dissipate higher plastic energy,so more toroidal surfaces should be considered in design of thin-walled structure.These achievements pave a way for designing high-performance cellular energy absorption devices.

Reversible Oxygen-Rich Functional Groups Grafted 3D Honeycomb-Like Carbon Anode for Super-Long Potassium Ion Batteries

Studies have found that oxygen-rich-containing functional groups in carbon-based materials can be used as active sites for the storage performance of K^(+),but the basic storage mechanism is still unclear.Herein,we construct and optimize 3D honeycomb-like carbon grafted with plentiful COOH/C=O functional groups(OFGC)as anodes for potassium ion batteries.The OFGC electrode with steady structure and rich functional groups can effectively contribute to the capacity enhancement and the formation of stable solid electrolyte interphase(SEI)film,achieving a high reversible capacity of 230 mAh g^(-1) at 3000 mA g^(-1) after 10,000 cycles(almost no capacity decay)and an ultra-long cycle time over 18 months at 100 mA g^(-1).The study results revealed the reversible storage mechanism between K^(+)and COOH/C=O functional groups by forming C-O-K compounds.Meanwhile,the in situ electrochemical impedance spectroscopy proved the highly reversible and rapid de/intercalation kinetics of K+in the OFGC electrode,and the growth process of SEI films.In particular,the full cells assembled by Prussian blue cathode exhibit a high energy density of 113 Wh kg^(-1) after 800 cycles(calculated by the total mass of anode and cathode),and get the light-emitting diodes lamp and ear thermometer running.

Honeycomb-like carbon materials derived from coffee extract via a “salty” thermal treatment for high-performance Li-I2 batteries

Sustainable,conductive,and porous carbon materials are ideal for energy storage materials.In this study,honeycomb-like carbon materials(HCM)are synthesized via a“salty”thermal treatment of abundant and sustainable coffee extract.Systematic materials characterization indicates that the as-prepared HCM consists of heteroatoms(N and O,etc.)doped ultra-thin carbon framework,possesses remarkable specific surface area,and excellent electrical conductivity.Such properties bestow HCM outstanding materials to be the blocking layer for Li-I2 battery,significantly eliminating the dissolution of I2 in the cathode region and stopping the I2 from shutting to anode compartment.Furthermore,our electrochemical investigation suggests that HCM could incur surface pseudo-capacitive iodine-ions charge storage and contribute additional energy storage capacity.As a result,the resultant Li-I2 battery achieves a robust and highly reversible capacity of 224.5 mAh·g−1 at the rate of 10 C.Even under a high rate of 50 C,the remarkable capacity of the as-prepared Li-I2 battery can still be maintained at 120.2 mAh·g−1 after 4000 cycles.

Boosting oxygen evolution reactivity by modulating electronic structure and honeycomb-like architecture in Ni_(2)P/N,P-codoped carbon hybrids

Oxygen evolution reaction(OER)as the foremost stumbling block to generate cost-effective clean fuels has received extensive attention in recent years.But,it still maintains the challenge to manipulate the geometric and electronic structure during single reaction process under the same conditions.Herein,we report a simple self-template strategy to generate honeycomb-like Ni_(2)P/N,P-C hybrids with preferred electronic architecture.Experiments coupled with theoretical results revealed that the synthesized catalyst has two characteristics:firstly,the unique honeycomb-like morphology not only enables the fully utilization of catalytic active sites but also optimizes the mass/electron transportation pathway,which favor the diffusion of electrolyte to accessible active sites.Secondly,N,P-C substrate,on the one hand,largely contributes the electronic distribution near Fermi level(E_(F))thus boosting its electrical conductivity.On the other hand,the support effect result in the upshift of d-band center and electropositivity of Ni sites,which attenuates the energy barrier for the adsorption of OH~àand the formation of*OOH.In consequence,the optimized Ni_(2)P/N,P-C catalysts feature high electrocatalytic activity towards OER(a low overpotential of 252 m V to achieve10 m A cm^(-2))and 10 h long-term stability,the outstanding performance is comparable to most of transition metal catalysts.This work gives a innovative tactics for contriving original OER electrocatalysts,inspirng deeper understanding of fabricating catalysts by combining theoretical simulation and experiment design.

Research on the Novel Honeycomb-Like Cabin Based on Computer Simulation

The antiknock capability and thermal protection performance of rescue capsules mainly depend on the structural design of the cabin.By designing a new type of cabin structure,it can resist the impact of explosion shock waves and thermal shocks.In this paper,a new honeycomb-like cabin is proposed;the model has a novel thermal insulation layer design.Then,the antiknock capabilities and thermal protection analysis are carried out by using computer software.The“Autodyn”analysis module in ANSYS Workbench 17.0 has been used to simulate the explosion of TNT with a certain quality in a single room.The pressure map over time and the pressure variation curve at different locations for a single room are obtained.Through the analysis module“Transient Structural,”the stress and deformation of the honeycomb-like cabin under the blast load are simulated.The“Transient Thermal”analysis module in the finite element software is used to conduct a transient thermal analysis on the cabin structure.The temperature map and the temperature rise curve of each layer of the cabin cases are obtained.The analysis results indicate that the honeycomb-like cabin design has a good antiknock capability and thermal protection performance,and it can meet the usage requirements of the rescue capsule under dangerous conditions.

N-doped honeycomb-like porous carbon towards high-performance supercapacitor

Biomass-derived porous carbon with developed pore structure is critical to achieving high performance electrode materials.In this work,we report a grape-based honeycomb-like porous carbon(GHPC)prepared by KOH activation and carbonization,followed by N-doping(NGHPC).The obtained NGHPC exhibits a unique honeycomb-like structure with hierarchically interconnected micro/mesopores,and high specific surface area of 1268 m^2/g.As a supercapacitor electrode,the NGPHC electrode exhibits a remarkable specific capacitance of 275 F/g at 0.5 A/g in a three-electrode cell.Moreover,the NGHPC//NGHPC symmetric supercapacitor displays a high energy density of 12.6 Wh/kg,and excellent cycling stability of approximately 95.2% capacitance retention after 5000 cycles at 5 A/g.The excellent electrochemical performance of NGHPC is ascribed to its high specific surface area,honeycomb-like structure and high-content of pyrodinic-N(36.29%).It is believed that grape-based carbon materials show great potential as advanced electrode materials for supercapacitors.

Porous honeycomb-like C3N4/rGO composite as host for high performance Li-S batteries

Lithium-sulfur (Li-S) batteries have attracted extensive attention along with the urgent increasing demand for energy storage owing to the high theoretical specific capacity and energy density, abundant reserves and low cost of sulfur. However, the practical application of Li-S batteries is still impeded due to the low utilization of sulfur and serious shuttle-effect of lithium polysulfides (LiPSs). Here, we fabricated the porous honeycomb-like C3N4 (PHCN) through a hard template method. As a polar material, graphitic C3N4 has abundant nitrogen content (-58%), which can provide enough active sites to mitigate shuttle-effect, and then conductive reduced graphene oxide (rGO) was introduced to combine with PHCN to form PHCN/rGO composite in order to improve the utilization efficiency of sulfur. After sulfur loading, the PHCN/rGO/S cathode exhibited an initial discharge capacity of 1,061.1 mA h g^-1 at 0.2 C and outstanding rate performance at high current density of 5 C (495.1 mA h g^-1), and also retained 519 mA h g^-1, after 400 cycles at 1 C. Even at high sulfur loading (4.3 mg cm^-2), the capacity fade rate was only 0.16% per cycle at 0.5 C for 200 cycles. The above results demonstrate that the special design of PHCN/rGO composite as sulfur host has high potential application for Li-S rechargeable batteries.

Honeycomb-like MXene/NiFeP_(x)–NC with“continuous”single-crystal enabling high activity and robust durability in electrocatalytic oxygen evolution reactions

The development of low-cost,stable,and robust non-noble metal catalysts for water oxidation is a pivotal challenge for sustainable hydrogen production through electrocatalytic water splitting.Currently,such catalysts suffer from high overpotential and sluggish kinetics in oxygen evolution reactions(OERs).Herein,we report a“continuous”single-crystal honeycomb-like MXene/NiFeP_(x)–N-doped carbon(NC)heterostructure,in which ultrasmall NiFeP_(x)nanoparticles(NPs)encapsulated in the NC are tightly anchored on a layered MXene.Interestingly,this MXene/NiFeP_(x)–NC delivers outstanding OER catalytic performance,which stems from“continuous”single-crystal characteristics,abundant active sites derived from the ultrasmall NiFeP_(x)NPs,and the stable honeycomb-like heterostructure with an open structure.The experimental results are rationalized theoretically(by density functional theory(DFT)calculations),which suggests that it is the unique MXene/NiFeP_(x)–NC heterostructure that promotes the sluggish OER,thereby enabling superior durability and excellent activity with an ultralow overpotential of 240 mV at a current density of 10 mA×cm^(−2).

Honeycomb-like polyaniline for flexible and folding all-solid-state supercapacitors

Porous polyaniline (PANI) was prepared through an efficient and costeffective method by polymerization of aniline in the NaCl solution at room temperature. The resulting PANI provided large surface area due to its highly porous structure and the intercrossed nanorod, resulting in good electrochemical performance. The porous PANI electrodes showed a high specific capacitance of 480 F·g^-1, 3 times greater than that of PANI without using the NaCl solution. We also make chemically crosslinked hydrogel film for hydrogel polymer electrolyte as well as the flexible supercapacitors (SCs) with PANI. The specific capacitance of the device was 234 F·g^-1 at the current density of 1 A·g^-1. The energy density of the device could reach as high as 75 W·h·kg^-1 while the power density was 0.5 kW·kg^-1, indicating that PANI be a promising material in flexible SCs.

P-doped CoSe_(2)nanoparticles embedded in 3D honeycomb-like carbon network for long cycle-life Na-ion batteries

We report for the first time a Na-ion battery anode material composed of P-doped CoSe_(2)nanoparticles(P-CoSe_(2))with the size of 5–20 nm that are uniformly embed in a 3 D porous honeycomb-like carbon network.High rate capability and cycling stability are achieved simultaneously.The honeycomb-like carbon network is rationally designed to support high electrical conductivity,rapid Na-ion diffusion as well as the accommodation of the volume expansion from the active P-CoSe_(2)nanoparticles.In particular,heteroatom P-doping within CoSe_(2)introduces stronger P-Co bonds and additional P-Se bonds that significantly improve the structure stability of P-CoSe_(2)for highly stable sodiation/desodiation over long-term cycling.P-doping also improves the electrical conductivity of the CoSe_(2)nanoparticles,leading to highly elevated electrochemical kinetics to deliver high specific capacities at high current densities.Benefiting from the unique nanostructure and atomic-level P-doping,the P-CoSe_(2)(2:1)/C anode delivers an excellent cycle stability with a specific capacity of 206.9 mA h g^(-1)achieved at 2000 mA g^(-1)after 1000 cycles.In addition,this material can be synthesized using a facile pyrolysis and selenization/phosphorization approach.This study provides new opportunities of heteroatom doping as an effective method to improve the cycling stability of Na-ion anode materials.

基于蜂窝仿生流场的质子交换膜燃料电池的性能研究及优化

为了增强质子交换膜燃料电池(PEMFCs)内部燃料分布的均匀性与水管理能力,本文研究了一种新型的基于仿生结构的蜂窝仿生流场。首先,根据蜂窝结构特征,搭建出三维多相流非等温几何模型并确立PEMFC的数学模型;其次,采用计算流体动力学Fluent软件对模型进行无关性与有效性验证,并对蜂窝仿生流场和常规平行流场的电池性能和燃料分布进行了模拟分析;最后,对比极化性能、气体流速分布、燃料与液态水组分浓度和电流密度分布,验证了蜂窝仿生流场设计的有效性。研究结果表明:采用蜂窝仿生流场的电池峰值功率密度比常规平行流场高15.6%,其内部水管理能力和燃料分布均匀性均强于平行流场;左端进气的蜂窝仿生流场比采用上端进气的蜂窝仿生流场在气体通路内具有更均匀的气体压力,可有效避免流道内产生局部涡流,其峰值功率密度可以达到0.3933 W/cm2。

类蜂窝结构高灵敏度裂变室探测器模拟仿真研究

目前的反应堆功率监测系统要求使用单一裂变电离室在适应反应堆堆芯的高γ辐射场下的中子注量率测量的同时可以以高灵敏度的脉冲工作模式适应反应堆启动阶段的低中子注量率情况下的测量。然而,由于裂变碎片在易裂变物质涂层中的射程较短,具有较强的自吸收效应,因此无法通过增大裂变材料涂层厚度提升探测器的灵敏度。本文提出了一种类蜂窝结构的圆柱栅格裂变室探测器,将探测器比表面积提高为普通圆柱电离室的3倍,从而在不增加裂变物质涂层厚度的情况下,大幅度增加了裂变物质的有效质量,实现了高的中子灵敏度。基于Geant4的蒙特卡罗模拟表明21片栅格板和2.5mg/cm^(2)的^(235)U涂层的裂变电离室可以实现3cps/nv的热中子探测灵敏度。使用Garfield++对探测器内电离电子的迁移和扩散的仿真结果表明,使用Ar/CO_(2)(96/4)作为工作气体可以平衡电离电子的漂移速度和横向扩散,并实现极间电压为725V时96.5%的电子迁移效率。本文的模拟和仿真结果表明,该类蜂窝结构裂变电离室在脉冲模式下具有高的热中子灵敏度,有希望适应反应堆从启动到满功率运行的宽量程的功率监测。

蜂窝状多孔碳材料装载硫单质及其在锂硫电池中的储能性能研究

单质硫及其放电最终产物Li_(2)S的绝缘性以及两者密度差异引起的结构坍塌等问题严重阻碍了锂硫电池的进一步发展,找寻合适的基体材料是解决上述问题的有效策略。本工作选用一种蜂窝状多孔碳作为硫正极的基体材料,通过常规的熔融扩散法将硫单质固定在碳孔隙中,并利用SEM、XRD、XPS和BET等方法对多孔碳@单质硫复合材料进行了表征。结果表明,硫单质均匀地负载在碳骨架中。同时,蜂窝状结构碳不仅为硫单质提供了电子导电网络,也保证了正极的稳定性。更重要的是,蜂窝状的结构为循环过程中硫正极的体积膨胀提供了一定的缓冲空间,缓解了结构坍塌这一问题。此外,碳基体丰富的孔隙度在一定程度上减少了多硫化物的穿梭。因此,在0.1C的倍率下,多孔碳@单质硫复合材料首次放电比容量高达1125.9 mAh/g,300次循环后比容量可保持305.1 mAh/g。

气升式内循环蜂窝陶瓷反应器降解2,4-二氯酚的研究

从以 2 ,4 二氯酚 (2 ,4 DCP)长期驯化的好氧活性污泥中分离出一株以 2 ,4 DCP为唯一碳源的菌种 ,将这种菌固定在气升式内循环蜂窝陶瓷反应器内 ,研究了此反应器在半连续流运行时 ,对 2 ,4 DCP单基质及其与苯酚共基质时对污染物的降解情况及降解动力学 .结果表明 ,2 ,4 DCP单基质时 ,反应器对氯酚的去除效果随着实验次数的增加而加快 ;2 ,4 DCP与苯酚共基质时 ,苯酚的降解速率随着半连续流实验次数的增加而加快 ,而氯酚的降解速率则表现出下降的趋势 .此外 ,还研究了此反应器在连续流运行时对 2 ,4 DCP的降解 ,水力停留时间为6h ,进水 2 ,4 DCP浓度为 6 9～ 1 0 2 4mg/L ,系统稳定状态对 2 ,4 DCP平均去除率为 96 5 % .运行中间断性以乙酸钠和蛋白胨作碳源替代 2 ,4 DCP 。

不同形貌HZSM-5的合成及其在催化二氧化碳加氢制备二甲醚中的应用

以正硅酸乙酯为硅源,四丙基氢氧化铵为模板剂,司盘80和吐温80为活化剂,分别制备了六棱柱状、纳米颗粒和类蜂窝状的HZSM-5型分子筛,用XRD、SEM、BET和NH3-TPD对合成的分子筛进行了表征,结果表明,类蜂窝状的HZSM-5型分子筛具有较大的比表面积和较强的酸性。将合成的分子筛与甲醇合成催化剂Cu OZn O-Al2O3机械混合,制得CO2加氢一步合成二甲醚的双功能催化剂。在反应温度270℃、反应压力3 MPa、空速1 800 m L/(gcat·h)、V(CO2)∶V(H2)=1∶3、m(Cu O-Zn O-Al2O3)∶m(类蜂窝HZSM-5)=1∶1的反应条件下,CO2的单程转化率和二甲醚的产率分别达到了45.4%和20.1%。

蜂窝陶瓷固定化酵母细胞生物催化剂制备过程研究

蜂窝陶瓷作为酵母细胞的吸附固定化载体,进行固定化酵母细胞生物催化剂制备过程研究,获得优化的工艺条件为:14℃下吸附30min,然后14℃下在反应器中连续培养2h。同时还得到了三个不同温度条件下,蜂窝陶瓷对酵母细胞的吸附动力学模型。

熔盐体系组成对二氧化碳电化学合成新型碳材料形貌影响

以碳酸盐为电解质,以铁、镍、镍铬合金等廉价金属材料为电极,研究构建了高温熔盐电解池,将CO2一步法转化为新型碳材料,并考察了熔盐组成及配比、电解温度、电流密度、电极材料等实验条件对碳材料形貌结构的影响。采用X射线能谱分析仪(EDS)、扫描电镜(SEM)、透射电镜(TEM)、比表面积测试仪(BET)、X射线衍射仪(XRD)及拉曼光谱仪(Raman)等手段对碳材料的元素组成、形貌结构、比表面积、结晶度、有序度等特性进行表征分析。研究结果表明,450~600℃温度范围内,电解多元混合熔盐体系主要生成无定形碳;同时,电解温度、电流密度、电解质组成及配比等对碳产物的比表面积具有明显影响;通过改变电解质体系,辅以调控电流密度及电解温度等实验参数,可实现碳纳米管、碳球及蜂窝状多孔碳等特定形貌碳材料的可控合成,其中碳纳米管的石墨化程度较高,且由碳原子组成的层状六方石墨晶体排列规则有序。

蜂窝式汽封流动性能的数值研究

建立了蜂窝式汽封流动特性的三维数值模型,系统地分析了蜂窝孔径、高度、汽封入口蒸汽压力和主轴转速等结构与运行参数对汽封内流动特性的影响。研究结果表明,在运行参数不变的情况下,减小蜂窝孔径或增加蜂窝高度都有利于降低汽封漏汽流量,提高密封效果;在结构参数不变的情况下,汽封漏汽流量随入口蒸汽压力增大而增加,但随主轴转速增大呈现减小的趋势。

类蜂窝复合夹层结构的力学特性及其在精密机床上的应用

为提高加工中心中立柱的静、动刚度及热刚度,提出一种类蜂窝胞元结构,并应用该结构对加工中心的关键部件进行重新设计。首先,针对蜂窝结构在共面方向承载力不足的问题,以传统六边形蜂窝胞元为对象,在外侧构建保护壁,构成类蜂窝结构,力学特性及仿真分析表明,强化后的结构具有更好的比刚度和承载性。其次,将机床立柱结构分为横梁和立柱两部分,将类蜂窝填充结构分别与"米"字形或"井"字形填充结构进行了对比分析,从定性和定量的角度评判方案的优劣。最后,计算了刀具在实际工况下的受力及主轴箱、导轨等处的生热状况,将力载荷和热载荷施加在立柱上,并对重新设计后的立柱进行了静、动力学分析及散热性能分析。结果表明:较"井"字形填充结构,类蜂窝填充结构的立柱质量减小了4.21%,沿z轴的变形下降了39.5%,一阶固有频率提高了29.22%,热稳态时间减少了81.39%。