Layered Structural PBAT Composite Foams for Efficient Electromagnetic Interference Shielding

The utilization of eco-friendly,lightweight,high-efficiency and high-absorbing electromagnetic interference(EMI)shielding composites is imperative in light of the worldwide promotion of sustainable manufacturing.In this work,magnetic poly(butyleneadipate-coterephthalate)(PBAT)microspheres were firstly synthesized via phase separation method,then PBAT composite foams with layered structure was constructed through the supercritical carbon dioxide foaming and scraping techniques.The merits of integrating ferroferric oxideloaded multi-walled carbon nanotubes(Fe3O4@MWCNTs)nanoparticles,a microcellular framework,and a highly conductive silver layer have been judiciously orchestrated within this distinctive layered configuration.Microwaves are consumed throughout the process of“absorption-reflection-reabsorption”as much as possible,which greatly declines the secondary radiation pollution.The biodegradable PBAT composite foams achieved an EMI shielding effectiveness of up to 68 dB and an absorptivity of 77%,and authenticated favorable stabilization after the tape adhesion experiment.

Enhanced activation of peroxymonosulfate by Fe/N co-doped ordered mesoporous carbon with dual active sites for efficient removal of m-cresol

The novel Fe-N co-doped ordered mesoporous carbon with high catalytic activity in m-cresol removal was prepared by urea-assisted impregnation and simple pyrolysis method.During the preparation of the Fe-NC catalyst,the complexation of N elements in urea could anchor Fe,and the formation of C3N4during urea pyrolysis could also prevent migration and aggregation of Fe species,which jointly improve the dispersion and stability of Fe.The FeN4sites and highly dispersed Fe nanoparticles synergistically trigger the dual-site peroxymonosulfate (PMS) activation for highly efficient m-cresol degradation,while the ordered mesoporous structure of the catalyst could improve the mass transfer rate of the catalytic process,which together promote catalytic degradation of m-cresol by PMS activation.Reactive oxygen species (ROS) analytic experiments demonstrate that the system degrades m-cresol by free radical pathway mainly based on SO_(4)^(-)·and·OH,and partially based on·OH as the active components,and a possible PMS activation mechanism by 5Fe-50 for m-cresol degradation was proposed.This study can provide theoretical guidance for the preparation of efficient and stable catalysts for the degradation of organic pollutants by activated PMS.

Achieving high-efficient photocatalytic persulfate-activated degradation of tetracycline via carbon dots modified MIL-101(Fe)octahedrons

The synergistic reaction of photocatalysis and advanced oxidation is a valid strategy for the degradation of harmful antibiotic wastewater.Herein,carbon dots(CDs)modified MIL-101(Fe)octahedrons to form CDs/MIL-101(Fe)composite photocatalyst was synthesized for visible light-driven photocatalytic/persulfate(PS)-activated tetracycline(TC)degradation.The electron spin resonance(ESR)spectra,scavenging experiment and electrochemical analysis were carried out to reveal that the high visible light-driven photocatalytic degradation activity of TC over CDs/MIL-101(Fe)photocatalysts is not only ascribed to the production of free active radicals in the CDs/MIL-101(Fe)/PS system(·OH,·SO_(4-),^(1)O_(2),h^(+)and·O_(2)^(-))but also attributed to the consumption of electrons caused by the PS,which can suppress the recombination of photo-generated carriers as well as strong light scattering and electron trapping effects of CDs.Finally,the possible degradation pathways were proposed by analyzing intermediates via liquid chromatography-mass spectrometry technique.This research presents a rational design conception to construct a CDs/PS-based photocatalysis/advanced oxidation technology with high-efficient degradation activity for the remediation of organic antibiotic pollutant wastewater and for the improvement of carrier transport kinetics of photocatalysts.

Ultralight pyrolytic carbon foam reinforced with amorphous carbon nanotubes for broadband electromagnetic absorption

For electromagnetic wave-absorbing materials,maximizing absorption at a specific frequency has been constantly achieved,but enhancing the absorption properties in the entire band remains a challenge.In this work,a 3D porous pyrolytic carbon(PyC)foam matrix was synthesized by a template method.Amorphous carbon nanotubes(CNTs)were then in-situ grown on the matrix surface to obtain ultralight CNTs/Py C foam.These in-situ grown amorphous CNTs were distributed uniformly and controlled by the catalytic growth time and can enhance the interface polarization and conduction loss of composites.When the electromagnetic wave enters the internal holes,the electromagnetic energy can be completely attenuated under the combined action of polarization,conductivity loss,and multiple reflections.The ultralight CNTs/Py C foam had a density of 22.0 mg·cm^(-3)and a reflection coefficient lower than-13.3 d B in the whole X-band(8.2-12.4 GHz),which is better than the conventional standard of effective absorption bandwidth(≤-10 dB).The results provide ideas for researching ultralight and strong electromagnetic wave absorbing materials in the X-band.

以CeO_(2)为载体的Fe基载氧体与CO反应机理模拟

化学链燃烧技术是一种新型的近“零碳”排放燃烧技术,载氧体在化学链燃烧反应过程中发挥着载氧和传热的双重作用。以活性催化组分为载体,通过调谐微观结构提高Fe基载氧体的反应性能是目前化学链领域的研究热点之一。基于密度泛函理论,以CeO_(2)为活性催化载体,对Fe基载氧体进行催化调谐。通过优化构建组合物模型,系统分析了组合物模型中Fe_(2)O_(3)团簇不同点位吸附CO的态密度、吸附能、差分电荷密度和活化能等电子结构特性参数。研究结果表明,Fe_(2)O_(3)团簇的电子向CeO_(2)(111)表面转移,Fe_(2)O_(3)团簇的吸附能为-3.92 eV,Fe2O3团簇与CeO_(2)(111)表面稳定结合;态密度(DOS)分析发现负载后的Fe_(2)O_(3)团簇p和d轨道在-8~0 eV电子向费米能级方向迁移,表明吸附作用增强。Fe_(2)O_(3)团簇p和d轨道中电子减少,现存电子向高能级跃迁,Fe_(2)O_(3)团簇电子活性增强,CO分子在Fe_(2)O_(3)/CeO2复合载氧体的Fe_(2)O_(3)团簇3个吸附位反应的活化能均降低。此外,CeO_(2)(111)增强了CO在Fe_(2)O_(3)团簇Fe顶位的吸附作用,吸附能由-0.33 eV增至-1.78 eV;同时,削弱了在O顶位的过强吸附作用,吸附能由-2.69 eV降至-2.32 eV,有利于后期CO_(2)分子脱离Fe_(2)O_(3)团簇表面,从而有效调谐Fe2O3团簇整体对CO的吸附效果,为Fe基载氧体的设计制备和优化调谐提供理论指导。

Effect of Ultrasonication on the Properties of Multi-walled Carbon Nanotubes/Hollow Glass Microspheres/Epoxy Syntactic Foam

Multi-walled carbon nanotubes（MWCNTs） reinforced hollow glass microspheres（HGMs）/epoxy syntactic foam was fabricated. The effects of ultrasonication on the density, compression strength, and water absorption properties were studied. Better dispersed MWCNTs can be obtained after ultrasonication treatment, but an increasing viscosity will lead to a larger amount of voids during syntactic foam preparation especially when the content of HGMs is more than 70 vol%. The existing voids will decrease the density of epoxy syntactic foam. However, the ultrasonication does not change the compression strength much. Ultrasonication treatment will decrease the water absorption content due to the better dispersion and hydrophobic properties of MWCNTs. But a significant increase of water absorption content occurs when HGMs is more than 70 vol%, which is attributed to the higher viscosity and larger amount of voids.

绿萝制备蓝色荧光碳量子点及对Fe^(3+)的检测

以绿萝为原料,通过水热法合成了蓝色荧光碳量子点(CQDs),考察了原料质量浓度、水热温度、CQDs浓度对CQDs荧光强度的影响,确定了最佳工艺条件:原料质量浓度3.3g/L、反应温度260℃、反应时间4h,此条件下制备的CQDs荧光强度最高。同时研究了盐离子浓度、紫外灯光照射时间、溶液pH对CQDs荧光强度的影响,结果表明CQDs有较好的盐稳定性和光稳定性,对pH有一定的依赖性,酸性条件下CQDs荧光强度相对较高。傅里叶变换红外光谱、X射线光电子能谱分析表明CQDs表面含有羟基、羧基等官能团,在水中有良好的溶解性。Fe^(3+)对CQDs的荧光有明显的猝灭作用,其他金属离子对其干扰性小,基于荧光强度与Fe^(3+)浓度之间的线性关系,CQDs能快速地检测水溶液中Fe^(3+)浓度,最低检测限为0.77μmol/L。

基于碳纤维强化的Fe^(0)混养反硝化脱氮效能与机制

以含NO_(3)^(-)-N合成废水为处理对象,对比了单独投加Fe^(0)与碳纤维强化Fe^(0)混养反硝化连续流反应器反硝化脱氮的效能。结果表明,在COD/NO_(3)^(-)-N为2.9~3.1、水力停留时间(HRT)为24 h时,投加碳纤维强化Fe^(0)的实验组R1对TN和NO_(3)^(-)-N平均去除率分别高达89.04%和97.13%,显著高于单独投加Fe^(0)的对照组R0。胞外聚合物(EPS)及电子传递活性(ETSA)变化规律表明,碳纤维的投入可进一步促进EPS生成,且强化了微生物对电子的利用率。扫描电镜-能量色散光谱仪(SEM-EDS)和X射线衍射仪(XRD)分析结果发现R1中Fe^(0)表面有明显的微生物腐蚀现象,FeO(OH)和含铁有机复合物是主要的腐蚀产物。微生物学分析表明,有机碳源投加量的提高及碳纤维的投加有效提高铁自养反硝化菌属丰度,促进反硝化功能基因的富集。

Bonding effect of liquid magnesium with open-celled carbon foam in interpenetrating phase composite

The issue of bonding formation in liquid metal/open-celled carbon foam(C_(of))systems was examined,taking into account the practical aspects of the synthesis of a new type of Mg-C metal material composite.The problem is complex due to the strong oxidation and intense evaporation of liquid magnesium,as well as the 3D geometry of the carbon component,where metal transport occurred through the foam cells’windows.Laboratory experiments performed at 700℃ in ceramic crucibles showed that spontaneous carbon foam infiltration by liquid metal is impossible under the applied conditions,either in an air atmosphere coupled with flux protection or under argon protection.Comparative tests performed in a UHV chamber filled with static pure Ar by a sessile drop method,coupled with non-contact heating and capillary purification at a test temperature of 700℃ directly in the UHV chamber,showed non-wetting behavior of the Mg/C_(of)couple with a correspondingly high contact angle of about 135°.The graphite capillary was then moved down,the liquid drop being slightly pressed into the foam,but these changes did not induce effective foam penetration.Despite the short contact time for the sessile drop test under an argon atmosphere,SEM+WDS analysis of the solidified Mg/C_(of)couple revealed the formation of an MgO interlayer at the interface,with a thickness of approx.1μm.The experimentally demonstrated presence of oxygen in the carbon foam sample,both before and after its contact with magnesium,points to oxide-type bonding being established between Mg and C_(of).This observation is in a good agreement with previous reports on the interface characterization of magnesium matrix composites reinforced with glassy carbon materials and carbon fibers by stir casting and pressure infiltration.Based on the findings of this study,a general structural scheme of the bonding process between carbon foam and liquid magnesium,as an important stage in the syntheses of Mg-C composites,was proposed.

金属有机骨架材料MIL-53(Fe)/C复合材料的制备及其光催化性能

通过溶剂热法合成了含有不同碳材料的MIL-53(Fe)/C复合材料,并且应用XRD、SEM、PL等进行表征。在氙灯光源的照射下,以ρ(罗丹明B)=10 mg/L溶液为污染物评价其光催化性能。结果表明,MIL-53(Fe)/AC复合材料能够抑制光生电子-空穴的复位,MIL-53(Fe)/AC复合材料显示出较好的光催化性能。

甲酸/甲酸钠还原体系对Fe(Ⅱ)EDTA络合脱硝液再生的影响

在络合脱硝反应中,Fe(Ⅱ)EDTA络合脱硝液的还原再生是应用难点之一,而甲酸/甲酸钠体系在钯炭(Pd/AC)催化剂作用下对Fe(Ⅱ)EDTA络合脱硝液具有较好的还原性。以此为基础,采用控制变量法,分别考察了超声功率、甲酸添加量、甲酸钠添加量和Pd/AC催化剂添加量对Fe(Ⅱ)EDTA络合脱硝液(脱硝效率为80%)还原再生效果的影响。结果表明,在不开启超声、Pd/AC催化剂作用下,甲酸/甲酸钠还原体系能够有效地还原Fe(Ⅱ)EDTA络合脱硝液中的NO,实现络合脱硝液的还原再生。当甲酸钠添加量为10.00 g/L,甲酸添加量为2.10 g/L,Pd/AC催化剂添加量为3.00 g/L时,得到的再生络合脱硝液在50℃下的脱硝性能最好(在60 min内脱硝效率达97%以上,在90 min内脱硝效率达80%以上)。继续进行多次络合脱硝-还原再生的连续实验,整个体系仍具备较好的脱硝性能(第6次切换时,持续吸收70~80 min的脱硝效率为85%左右)。该研究结果可为络合脱硝连续化的中试试验以及工程应用提供参考。

Carbon foam with microporous structure for high performance symmetric potassium dual-ion capacitor

A novel carbon foam with microporous structure(CFMS),with the advantages of a simple fabrication process,low energy consumption,large specific surface area and high conductivity,has been prepared by a facile one-step carbonization.In addition,the carbon foam possesses suitable interlayer spacing in short range which is flexible to accommodate the deformation of carbon layer caused by the ion insertion and deinsertion at the charge and discharge state.Furthermore,a low cost carbon-based symmetric potassium dual-ion capacitor(PDIC),which integrates the virtues of potassium ion capacitors and dual-ion batteries,is successfully established with CFMS as both the battery-type cathode and the capacitor-type anode.PDIC displays a superior rate performance,an ultra-long cycle life(90%retention after 10000 cycles),and a high power density of 7800 W kg^-1 at an energy density of 39Whkg^-1.The PDIC also exhibits excellent ultrafast charge and slow discharge properties,with a full charge in just 60 s and a discharge time of more than 3000 s.

Preparation and modulation of a novel thin-walled carbon foam

By foaming and carbonization processes under atmospheric pressure, a novel thin-walled carbon foam with developed foam structure was successfully prepared from loose medium component(LMC) separated from raw coal by extraction and back-extraction method. The influences of foaming time, carbonization time, and micromolecule content on foam structure were investigated by scanning electron microscope and mercury injection data. Moreover, foaming mechanism of LMC was analyzed and expounded. The results showed that spherical pores and uniform ultrathin pore walls constitute threedimensional foam structure of carbon foam and foam structure is developed with well connectivity.The effects of foaming time, carbonization time, and micromolecule content on foam structure are significant. Especially, average pore diameters of carbon foams prepared from the extracts of LMC are much smaller. With the rise of extraction rate, average pore diameter decreases and pore size distribution is more concentrated on the aperture section of 0–10 μm.

High performance columnar-like Fe2O3@carbon composite anode via yolk@shell structural design

Conversion-type reaction anode materials with high specific capacity are attractive candidates to improve lithium ion batteries(LIBs), yet the rapid capacity fading and poor rate capability caused by drastic volume change and low electronic conductivity greatly hinder their practical applications. To circumvent these issues, the successful design of yolk@shell Fe2 O3@C hybrid composed of a columnar-like Fe2O3 core within a hollow cavity completely surrounded by a thin, self-supported carbon(C) shell is presented as an anode for high-performance LIBs. This yolk@shell structure allows each Fe2O3 core to swell upon lithiation without deforming the carbon shell. This preserves the structural and electrical integrity against pulverization, as revealed by in situ transmission electron microscopy(TEM) measurement. Benefiting from these structural advantages, the resulting electrode exhibits a high reversible capacity(1013 m Ah g-1 after80 cycles at 0.2 A g-1), outstanding rate capability(710 m Ah g-1 at 8 A g-1) and superior cycling stability(800 m Ah g-1 after 300 cycles at 4 A g-1). A Li-ion full cell using prelithiated yolk@shell Fe2 O3@C hybrid as the anode and commercial Li CoO2(LCO) as the cathode demonstrates impressive cycling stability with a capacity retention of 84.5% after 100 cycles at 1 C rate, holding great promise for future practical applications.

Self-supported Ni2P nanosheets on low-cost three-dimensional Fe foam as a novel electrocatalyst for efficient water oxidation

Electrochemical water splitting into hydrogen and oxygen is a promising strategy for future renewable energy conversion devices.The oxygen evolution reaction(OER)is considered as the bottleneck reaction in an overall water splitting system because it involves 4e- and 4H+ transfer processes.Currently,it is highly desirable to explore low-cost alternative catalysts for OER at ambient conditions.Herein,we report for the first time that nickel phosphide(Ni2P)nanosheets can be facilely grown on Fe foam(FF)as an efficient electrocatalyst for OER with excellent durability and catalytic activity under alkaline conditions.To reach a current density of 10 m A/cm2,the Ni2P-FF catalyst required a low overpotential of only 198 mV for OER.The catalyst’s high OER activity and durability were well maintained at a high current density.The required overpotentials were only 267 and 313 mV to achieve the current densities of 100 and 300 m A/cm2,respectively.The combination of low-cost Fe foam with Ni2P provides a promising low-cost catalyst for large-scale application of electrocatalytic water splitting.

Dual template approach for the synthesis of hierarchically mesocellular carbon foams

We demonstrated a simple and effective dual-templating approach for the synthesis of hierarchically mesocellular carbon foams by using nonionic surfactant of sorbitan monooleate and silica colloid particles as sacrificial templates, and resorcinol/ formaldehyde as carbon source. The representative carbon foam has dual mesopore sizes of 4 and 10 nm, and possesses the specific surface area of 580 m^2/g and the total pore volume of 0.80 cm^3/g.

Investigation of carbon contamination in lost foam castings of low carbon steel

Lost foam casting(LFC) process is a special casting method in which polymeric foam patterns with refractory coatings are utilized as a mould component. In this work, four types of foam: expandable polyethylene(EPE), expandable polypropylene(EPP) and expandable polystyrene(EPS) foams with two different densities were employed as pattern materials. LFC and conventional green sand mould casting methods were used to cast a low carbon steel, A216 Grade WCB. Both casting processes were carried out at 1,580 °C. Chemical analysis results showed that the carbon contamination level was high and was influenced by pattern type. Metallographic investigations revealed a significant increase in the percentage of pearlite phase in all LFC samples. Densities of manufactured samples were calculated in order to evaluate porosity of the products. It was determined that the densities of the LFC samples were lower than the green sand mould cast reference sample(RS). Vickers hardness tests were also carried out and increments in hardness values with increased carbon content was observed.

Facile preparation of N-doped corncob-derived carbon nanofiber efficiently encapsulating Fe2O3 nanocrystals towards high ORR electrocatalytic activity

Facile preparation of cost-effective and durable porous carbon-supported non-precious-metal/nitrogen electrocatalysts for oxygen reduction reaction(ORR)is extremely important for promoting the commercialized applications of such catalysts.In this work,the FeCl3-containing porphyrinato iron-based covalent porous polymer(FeCl3·FeP or-CPP)was fabricated in-situ onto porous corncob biomass supports via a simple one-pot method.Subsequent thermal-reduction pyrolysis at 700℃-900℃with CO2 gas as an activating agent resulted in Fe2O3-decorated and N-doped graphitic carbon composite Fe2O3@NC&bio-C with a high degree of graphitization of Fe-involved promotion during pyrolysis(Fe2O3=FeCl3·FePor-CPP derived Fe2O3;NC=N-doped graphene analog;bio-C=the corncob-derived hierarchically porous graphitic biomass carbon framework).The derivedα-Fe2O3 andγ-Fe2O3 nanocrystals(5-10 nm particle diameter)were all immobilized on the N-doped bio-C micro/nanofibers.Notably,the Fe2O3@NC&bio-C obtained at the pyrolysis temperature of 800℃(Fe2O3@NC&bio-C-800),exhibited unusual ORR catalytic efficiency via a 4-electron pathway with the onset and half-wave potentials of 0.96 V and 0.85 V vs.RHE,respectively.In addition,Fe2O3@NC&bio-C-800 also exhibited a high and stable limiting current density of-6.0 mA cm-2,remarkably stability(larger than 91%retention after 10000 s),and good methanol tolerance.The present work represents one of the best results for iron-based biomass material ORR catalysts reported to date.The high ORR activity is attributed to the uniformly distributedα-Fe2O3 andγ-Fe2O3 nanoparticles on the N-enriched carbon matrix with a large specific surface area of 772.6 m^2 g^-1.This facilitates favor faster electron movement and better adsorption of oxygen molecules on the surface of the catalyst.Nevertheless,comparative studies on the structure and ORR catalytic activity of Fe2O3@NC&bioC-800 with Fe2O3@bio-C-800 and NC&bio-C-800 clearly highlight the synergistic effect of the coexisting Fe2O3 nanocrystals,NC,and bio-C on the ORR performance.

An Equivalent Substitute Strategy for Constructing 3D Ordered Porous Carbon Foams and Their Electromagnetic Attenuation Mechanism

Three-dimensional(3D)ordered porous carbon is generally believed to be a promising electromagnetic wave(EMW)absorbing material.However,most research works targeted performance improvement of 3D ordered porous carbon,and the specific attenuation mechanism is still ambiguous.Therefore,in this work,a novel ultra-light egg-derived porous carbon foam(EDCF)structure has been successfully constructed by a simple carbonization combined with the silica microsphere template-etching process.Based on an equivalent substitute strategy,the influence of pore volume and specific surface area on the electromagnetic parameters and EMW absorption properties of the EDCF products was confirmed respectively by adjusting the addition content and diameter of silica microspheres.As a primary attenuation mode,the dielectric loss originates from the comprehensive effect of conduction loss and polarization loss in S-band and C band,and the value is dominated by polarization loss in X band and Ku band,which is obviously greater than that of conduction loss.Furthermore,in all samples,the largest effective absorption bandwidth of EDCF-3 is 7.12 GHz under the thickness of 2.13 mm with the filling content of approximately 5 wt%,covering the whole Ku band.Meanwhile,the EDCF-7 sample with optimized pore volume and specific surface area achieves minimum reflection loss(RL_(min))of−58.08 dB at 16.86 GHz while the thickness is 1.27 mm.The outstanding research results not only provide a novel insight into enhancement of EMW absorption properties but also clarify the dominant dissipation mechanism for the porous carbon-based absorber from the perspective of objective experiments.

Nitrogen-rich hierarchically porous carbon foams as high-performance electrodes for lithium-based dual-ion capacitor

Nitrogen-rich porous carbonaceous materials have shown great potential in energy storage and conversion applications due to their facile fabrication,high electronic conductivity,and improved hydrophilic property.Herein,three-dimensional porous N-rich carbon foams are fabricated through a one-step carbonization-activation method of the commercial melamine foam,and displaying hierarchically porous structure(macro-,meso-,and micro-pores),large surface area(1686.5 m2 g^-1),high N-containing level(3.3 at%),and excellent compressibility.The as-prepared carbon foams as electrodes for quasi-solid-state supercapacitors exhibit enhanced energy storage ability with 210 F g^-1 and 2.48c at 0.1 A g^-1,and150 F g^-1 and 1.77 F cm^-2 at 1 A g^-1,respectively.Moreover,as an electrode for lithium-based dual-ion capacitor,this distinctive porous carbon also delivers remarkable specific capacitance with 143.6 F g^-1 at0.1 A g^-1 and 116.2 F g^-1 at 1 A g^-1.The simple preparation method and the fascinating electrochemical performance endow the N-rich porous carbon foams great prospects as high-performance electrodes for electrochemical energy storage.