Hollow Materials Research Articles

PERENCANAAN BEKISTING DAN PERANCAH PADA GEDUNG BERTINGKAT DENGAN SISTEM ZONASI (STUDI KASUS : PROYEK APARTEMEN DARMO HILL SURABAYA)

In the implementation method most contractors use conventional formwork which takes longer time. Therefore, it is necessary to use an innovation with semi-conventional system formwork method which is a combination of multiplex and hollow material. The purpose of this study is to analyze the strength of the half-system formwork, its implementation, and the operational costs of the project of 1 to 9 floors with a total area of 5,708.255m2. The data used include shop drawings and work unit prices of Surabaya City 2018. Microsoft Excel 2016 was for the calculations and Microsoft Project 2016 was for the scheduling. The calculations resulted semi-conventional formwork using wood and hollow steel of beam and slab formworks on 161 work days Rp. 2.790.745.668,86.

Metal organic framework-derived Co3O4/NiCo2O4 hollow double-shell polyhedrons for effective photocatalytic hydrogen generation

Hollow polyhedron materials have the characteristics of low density, high area ratio, strong light absorption and the short distance of mass transport, etc., which have come to the foreground in recent years. In this work, ZIF-67/Co-Ni double hydroxide (DH) was prepared using ZIF-67 as a precursor and then calcined to form Co3O4/NiCo2O4 hollow double-shell polyhedrons (HDSPs). This unique self-supporting hollow double-shell catalyst effectively avoids the aggregation of the catalyst and provides a unique reaction platform for the photocatalytic hydrogen production reaction. On the one hand, the thin shell reduces the penetration loss of incident light, and there are multiple refractions and scattering occur inside the shell, thereby effectively improving the light-trapping ability. On the other hand, the Co3O4/NiCo2O4 HDSPs not only shortens the transport distance of photo-generated carriers but also provides abundant active sites, which effectively inhibiting the recombination of electrons and holes. Density functional theory (DFT) calculations show that the formation of a NiCo2O4 shell outside of Co3O4 is more conducive to the separation and transfer of electrons. Therefore, the Co3O4/NiCo2O4 HDSPs can facilitate the separation and migration of carriers and effectively increase the hydrogen evolution rate of the catalyst. This work shows the important role of hollow double-shell materials and provides new ideas for the preparation of hollow double-shell catalysts.

Amorphous cobalt oxide decorated halloysite nanotubes for efficient sulfamethoxazole degradation activated by peroxymonosulfate

In this study, a new hollow nanotube material, 30% Co–CHNTs was prepared by the impregnation–chemical reduction–calcination method. This material can be used as a peroxymonosulfate (PMS) activator to catalyse the degradation of sulfamethoxazole (SMX). The best reaction conditions that correspond to the degradation rate of SMX, up to 97.5%, are as follows: the concentration of SMX is 10 mg L−1, the amount of catalyst is 0.20 g L−1, the dosage is 1.625 mM, and the solution pH is 6.00. X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectrometry (ICP-OES) show that the calcined composites mainly stimulate an increase in the content of bivalent cobalt in PMS and reduce the leaching of cobalt ions after the reaction. Additionally, the 30% Co–CHNTs + PMS reaction system exhibits a reasonable SMX degradation rate in a natural organic matter solution and excellent stability after three repeated experiments. Furthermore, the possible degradation mechanism in the 30% Co–CHNTs + PMS reaction system was analysed through electron paramagnetic resonance (EPR) and free-radical capture experiments, and it was observed that the non-radical degradation of 1O2 plays a leading role in SMX degradation. Finally, according to the nine degradation intermediates detected by liquid chromatography-mass spectrometry (LC–MS), four possible SMX degradation routes were proposed. This study proved that a 30% Co–CHNTs heterogeneous catalyst is easily prepared, inexpensive, and environmentally friendly and has potential application in antibiotic wastewater treatment.

Template-free single-step preparation of hollow CoO nanospheres using pulsed laser ablation in liquid enviroment

Owing to their unique properties, hollow nanoparticles have attracted tremendous attention in various research fields. However, it is a still challenge to prepare hollow nanoparticles without hard or soft template. In this study, high purity cobalt oxide (CoO) hollow nanosphere was experimentally obtained using pulsed laser ablation (PLA) in ethanol–water mixture. The morphological and optical properties of the fabricated nanospheres were investigated via different analytical techniques, including scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, and ultraviolet–visible spectroscopy. Selected area electron diffraction, and energy-dispersive X-ray spectroscopy were utilized to evaluate the crystalline structure as well as the chemical composition of the fabricated materials, respectively, The ethanol/water mixture was varied during the ablation process from 0 to 70 % v/v and found to have a significant impact on the size, shape, and structure of the produced nanoparticles. The average size was found to be about 100 nm for the 0–30% v/v of ethanol and around 200 nm for the 50 and 70% v/v of ethanol. It was also shown that the optimum ratio of ethanol–water mixture for the formation of hollow nanoparticles is between 5 and 30% v/v as the formation the hollow structures is directly associated with the saturation of the gas in the medium. A possible mechanism for the formation of hollow structure CoO using pulsed laser ablation in ethanol/mixture media is discussed. This study paves the way for fabrication of template-free hollow nanosphere materials for several applications.

Ultra-thin N-doped carbon coated SnO2 nanotubes as anode material for high performance lithium-ion batteries

Tin dioxide nanotubes coated with ultrathin N-doped carbon film (N-doped SnO2/C NTs) are prepared through a sacrificial template method for the first time. It was employed as anodes for lithium-ion batteries (LIBs) and delivered a high reversible capacity of 909.5 mAh g−1 at 0.5 A g−1 after 200 cycles, outstanding stability 551.7 mAh g−1 after 500 cycles at 1 A g−1, and excellent rate performance of 1069.2 mAh g−1 after 280 cycles. Such superior electrochemical performance is owning to the N-doped carbon coating which improved the conductivity of the NTs, which is essential for higher performance LIBs. The special designed whole nanotube structure provides extensive surface and pores to accommodate Li, meanwhile, prohibited the volume expansion during cycling test. The electrochemical performanceof pouch-type cells further demonstrates the SnO2/C NTs as a promising candidate for LIBs anode. This study has shed a light on the LIB anode materials design and preparation and made such hollow nanostructured materials a potential candidate to replace commonly used graphite materials.

Construction of internal and external defect electrode materials based on hollow manganese-cobalt-nickel sulfide nanotube arrays

The deficient active sites and poor conductivity of transition metal sulfides result in low energy density of supercapacitors that limits their extensive application. In this work, hollow manganese-cobalt-nickel sulfide nanotube arrays with the pore diameter about 40 nm are synthesized by three steps, and then chemical reduction strategy is used to build hollow trimetallic electrode materials with internal and external defects. During the whole process, due to the strong reducibility and small radius of H−, metal ions, which locate inside and outside the tube, are partially reduced from high oxidation states to low oxidation states, then the corresponding metal-sulfur bonds are broken and sulfide ions escape from active materials to form sulfur vacancies. Enhanced electrochemical performance of the electrode with vacancy (from 2944F g−1 to 3794F g−1 at 1 A g−1) demonstrates that the introduce of vacancy can facilitate electrochemical reaction kinetics due to the increased electron density of metal ions and active sites. In addition, the assembled asymmetric supercapacitor has a maximum voltage window of 1.8 V and displays a high energy density of 85.2 Wh kg−1 under a power density of 1030 W kg−1, showing the promising application in electrochemical energy storage fields.

Two-Dimensional Mesoporous Copper Hydroxide Nanosheets Shelled on Hollow Nitrogen-Doped Carbon Nanoboxes as a High Performance Aptasensing Platform

The design of metal hydroxide nanosheets on hollow carbonaceous nanostructures has attracted immense attention because of their unparalleled physical/chemical properties with sizeable intrinsic capability to load specific chemicals. Herein, a novel metal hydroxide based on hollow nitrogen-doped carbon nanoboxes shelled with a nanoporous copper hydroxide nanosheet (Cu(OH)2@N–C n-box) was fabricated. The structure of fabricated hollow nanomaterials was fully characterized by various physicochemical characterization techniques such as field emission scanning electron microscopy (FESEM), high-resolu1tion transmission electron microscopy (HRTEM), Brunauer–Emmett–Teller (BET) method, thermogravimetric analysis (TGA), powder X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) and Raman spectroscopies, which confirmed that a complex core–shell structure with ordered two-dimensional Cu(OH)2 nanostructures on N–C n-box was successfully prepared. The Cu(OH)2@N–C n-box is used to fabricate an advanced electrochemical aptasensor to measure the protein enzyme trypsin. In addition, it acts as an excellent substrate with abundant functional groups and a large surface area for fixing and bonding aptamers on the modified glass-carbon surface. Each step of electrode surface modification was investigated through ferro/ferri cyanide probe signal changes. The designed aptasensor can determine trypsin in a linear concentration between 10 to 80 pg/mL and 10 to 80 ng/mL with a detection limit of 3 pg/mL. The proposed system also has a desirable selectivity in the presence of different interferences. This is the first report on the rational design of hollow carbonaceous materials hybridized Cu(OH)2 for the electrochemical application.

MOFs-derived hollow Copper-based sulfides for optimized electromagnetic behaviors

The preparation of hollow materials is one of the most feasible ways to obtain efficient electromagnetic wave (EMW) absorbers. Herein, using the copper-based metal–organic frameworks (Cu-MOF-74) as templates, hollow copper-based sulfides with various morphologies (rod-like, cubic, and dodecahedral) were designed and synthesized. The outer Cu2S and/or Cu31S16 shell possesses excellent electronic conductivity and abundant heterogeneous interfaces, while the inner hollow cavity endows the absorbers with lightweight characteristics and good impedance matching according to the Maxwell-Garnett (MG) theory. Accordingly, the effective absorption bandwidth reaches 6.2 GHz at 2.3 mm with 20 wt% filler loading, exhibiting superior performance compared with the vast majority of previous MOFs derived absorbers. Furthermore, our study can serve a guide to construct hollow structured nanocomposites to tune electromagnetic parameters and strengthen EMW absorption properties.

石墨烯增强空心微点阵材料的制备与表征

石墨烯增强空心微点阵材料的制备与表征

Numerical Simulation of the Water Vapor Separation of a Moisture-Selective Hollow-Fiber Membrane for the Application in Wood Drying Processes.

In this study, a simplified two-dimensional axisymmetric finite element analysis (FEA) model was developed, using COMSOL Multiphysics® software, to simulate the water vapor separation in a moisture-selective hollow-fiber membrane for the application of air dehumidification in wood drying processes. The membrane material was dense polydimethylsiloxane (PDMS). A single hollow fiber membrane was modelled. The mass and momentum transfer equations were simultaneously solved to compute the water vapor concentration profile in the single hollow fiber membrane. A water vapor removal experiment was conducted by using a lab-scale PDMS hollow fiber membrane module operated at constant temperature of 35 °C. Three operation parameters of air flow rate, vacuum pressure, and initial relative humidity (RH) were set at different levels. The final RH of dehydrated air was collected and converted to water vapor concentration to validate simulated results. The simulated results were fairly consistent with the experimental data. Both experimental and simulated results revealed that the water vapor removal efficiency of the membrane system was affected by air velocity and vacuum pressure. A high water vapor removal performance was achieved at a slow air velocity and high vacuum pressure. Subsequently, the correlation of Sherwood (Sh)–Reynolds (Re)–Schmidt (Sc) numbers of the PDMS membrane was established using the validated model, which is applicable at a constant temperature of 35 °C and vacuum pressure of 77.9 kPa. This study delivers an insight into the mass transport in the moisture-selective dense PDMS hollow fiber membrane-based air dehumidification process, with the aims of providing a useful reference to the scale-up design, process optimization and module development using hollow fiber membrane materials.

Enhancing Catalytic Conversion of Polysulfides by Hollow Bimetallic Oxide-Based Heterostructure Nanocages for Lithium-Sulfur Batteries

Performance improvement of lithium-sulfur batteries (LSBs) is restricted by the dissolution and shuttle of lithium polysulfides (LiPSs). Prussian blue analogs (PBAs) and their derived nanomaterials are ideal sulfur-fixing materials owing to their abilities to anchor LiPSs, accelerate redox conversion, and smooth Li2S precipitation. Herein, the hollow CoxFe3–xO4 heterostructure nanocages with highly interconnected pore architecture obtained by a PBA-assisted strategy are synthesized to overcome the abovementioned obstructions of LSBs. It is found that the bimetallic oxide-based heterostructure can not only inhibit LiPS diffusion via forming metal–sulfur bonds but also accelerate the LiPS conversion kinetics. Meanwhile, the hollow porous structure contributes to the physical confinement of LiPSs and acts as a buffer for the volume change. Thereby, the rate capability and cycling stability of hollow CoxFe3–xO4@S composite electrodes have been improved significantly. As a result, the hollow CoxFe3–xO4@S cell displays an excellent initial capacity of 1301.6 mAh g–1 at a current density of 200 mA g–1. Even at 1 A g–1, it exhibits an outstanding initial capacity of 898.9 mAh g–1 with a negligible capacity loss rate, which is only 0.106% per cycle after 500 cycles. This work provides a new perspective for the construction and design of multifunctional hollow heterostructure materials for more efficient and stable LSBs.

Hollow upconversion nanoparticles: Synthesis and luminescence in comparison with their solid counterparts

Upconversion nanoparticles (UCNPs) have attracted a lot of interest in recent years due to their unique optical properties and potential for use in many different applications. However, direct synthesis of UCNPs with hollow structure at room temperature remains challenging. Here, ultra-facile one-pot synthesis of hollow Yb/Er co-doped NaBiF4 UCNPs at room temperature is reported. The NaBiF4:Yb,Er nanoparticles exhibit bright upconversion luminescence (UCL) upon near infrared excitation at 980 nm. Benefiting from the inherent advantages of the hollow structure (large surface permeability and large internal surface area), NaBiF4:Yb,Er hollow nanoparticles have superior luminescence properties than their solid counterparts. The UCL intensity of NaBiF4:Yb,Er hollow nanoparticles is 6.8 times that of solid counterparts, and its upconverison quantum efficiency is almost 10 times that of solid counterparts. Successful synthesis of these hollow UCNPs at room temperature in one-pot makes large-scale production possible due to the simplicity and low temperature nature of the synthesis and opens new ways to load sensitizer dyes or other materials for enhanced upconversion emission or multiplexed assays/imaging, or loading of photosensitive drugs for therapeutic applications. These finding will encourage researchers to further explore hollow structural materials with excellent UCL properties in the future.

Design and Analysis of Parison Blow Molding Using Adaptive Mesh

Blow Molding is one of the most versatile and economical process available for molding hollow materials. When polyethylene is stretched, it exhibits strain-hardening properties, which are temperature, pressure, velocity and strain-rate dependent. In this paper, preform is made by extrusion and forced between two halves by pressurization. This process includes isothermal and transient flow of Newtonian fluid in complex geometries simultaneous with structuring and solidification. A time dependent problem is defined and setting material properties and boundaries condition for bottle blow molding. Numerical data available in POLYDATA for a time dependent problem using ANSYS POLYFLOW were applied. Results display in form contours associated with different variables at different time steps and good agreement with the bottle thickness profile is observed. In this paper, the analysis of the stretch-blow molding (SBM) process of polyethylene terephthalate (PET), parison plastic bottles is studied by the finite element method (FEM). A hyper elastic constitutive behavior was calibrated using material data available in literature in variant high temperatures and strain rates and was used in the numerical simulation. Hydrostatic pressure with convention heat transfer has been used instead of a blowing process. Comparisons of numerical results with experimental observations demonstrate that the model can predict an overall trend of thickness distribution. Through the study, it becomes clear that the proposed model is applicable for simulating the stretch-blow molding process of PET bottles, and is capable of offering helpful knowledge in the production of bottles and the design of an optimum preform.

Flame aerosol synthesis of hollow alumina nanoshells for application in thermal insulation

Commercial implementation of hollow nanoshell materials is often limited by difficult scale-up and high cost. Here we present a scalable, continuous, and potentially low-cost route to hollow nanostructured materials using a High Temperature Reducing Jet flame aerosol reactor. The key advantage of this process over traditional flame aerosol synthesis methods is separation of flame chemistry and particle formation, which allows production of hollow nanoshells from an aqueous salt solution without any template or surfactant. We produced amorphous hollow alumina with an average diameter of 181 nm and shell thickness below 10 nm, and demonstrated the generality of the method by also producing hollow SiO2, ZrO2, Ga2O3, and Co2O3. We characterized the morphology, phase transition, thermal stability, and thermal conductivity of the flame-made hollow alumina by electron microscopy, x-ray diffraction, and thermal analysis methods. As a prototypical application, we incorporated hollow alumina into thermal insulation, combining it with common fiberglass insulation to reduce the thermal conductivity by 30% relative to pure fiberglass, to 0.028 W m−1 K−1 while maintaining robust fire-resistance and elasticity.

Hollow structures as drug carriers: Recognition, response, and release.

Hollow structures have demonstrated great potential in drug delivery owing to their privileged structure, such as high surface-to-volume ratio, low density, large cavities, and hierarchical pores. In this review, we provide a comprehensive overview of hollow structured materials applied in targeting recognition, smart response, and drug release, and we have addressed the possible chemical factors and reactions in these three processes. The advantages of hollow nanostructures are summarized as follows: hollow cavity contributes to large loading capacity; a tailored structure helps controllable drug release; variable compounds adapt to flexible application; surface modification facilitates smart responsive release. Especially, because the multiple physical barriers and chemical interactions can be induced by multishells, hollow multishelled structure is considered as a promising material with unique loading and releasing properties. Finally, we conclude this review with some perspectives on the future research and development of the hollow structures as drug carriers.

Effects of nitrogen-doping structural changes of spherical hollow graphene on the growth of MoS2+x nanosheets and the enhanced hydrogen evolution reaction

MoS2, a two-dimensional (2D) layered structural transition metal dichalcogenide (TMDs), has been widely investigated towards hydrogen evolution reaction (HER) in previous few years. Except for the inert basal plane sites of the MoS2 itself, its inherent low conductivity also hinders the electron transfer process, which adversely affects its efficiency towards HER. Therefore, how to expose more edge active sites and at the same time improve the conductivity of MoS2, either intrinsically or with the help of high conductive substrates, is a key means to improve the HER performance of MoS2. Herein, the polystyrene (PS) nanospheres are used not only as an intercalation agent of graphene carbon sheets, but also as a spherical template for the preparation of 3D spherical hollow graphene. Different nitrogen precursors and nitrogen doping methods are used to prepare the 3D spherical hollow graphene substrate materials with different nitrogen-doping structures, such as amine N, pyrrolic N, pyridinic N or quaternary N. The investigation results show that the structure of doped nitrogen atom has a great influence on the loading of molybdenum disulfide. Among them, amine N was the most favorable for the loading of molybdenum disulfide, followed by pyrrole N, quaternary N and pyridine N. Moreover, the structure of doped N active sites synthesized by different preparation methods can also affect the uniform distribution of molybdenum disulfide on 3D spherical hollow graphene and the corresponding HER performance. The results show that, using ammonia as nitrogen source and PS microspheres as template, the prepared molybdenum disulfide loaded 3D spherical hollow graphene electrode material has the best HER performance, which should be attributed to the uniform distribution of the molybdenum disulfide and its close combination with the substrate, as well as the 3D spherical hollow structure. Moreover, the amorphous structure of molybdenum disulfide formed in the hydrothermal process can also improve the activity of HER.

The effects of Al-doped to cathode material based on hollow microspheres of nickel–manganese on sodium-ion batteries

Sodium-ion batteries (SIBs) are expected to be a great substitute for lithium ion batteries. Although there are many difficulties to overcome, SIBs have become one of the most important research areas for large-scale energy storage equipment. The spherical particles are conducive to the contact between the cathode material and the electrolyte, which could increase the electrochemical reaction area, and improve the deintercalation rate of sodium ions during charging and discharging. In this paper, a precipitation method was used to prepare spherical MnCO3 material as template and raw material. After all the raw materials were weighed with the molar ratios of Na0.67Mn0.67–0.75x Ni0.33Al x O2, a series of hollow micro-spherical sodium-ion cathode materials were synthesized by the conventional high-temperature solid-state method. The effects of Al-doped on the structure and electrochemical performance of Na0.67Ni0.33Mn0.67O2 was studied, and it was founded that the samples doped with Al had smaller particle size than that without Al. The electrochemical tests showed that Na0.67Mn0.595Ni0.33Al0.1O2 (x = 0.1) exhibite superior high-rate capabilities and cyclic stability. And the hollow microsphere structure has a higher capacity, the first discharge capacity at 0.1C reach 128 mAh g−1.

Effect of formula factors on the properties of HPMC plant hollow capsule film

In order to explore the effect of the hollow capsule material formulation on the capsule glue and film formation, this study used hydroxypropylmethylcellulose (HPMC), carrageenan, KCl and Tween 80 as raw materials to determine the production of HPMC hollow capsules suitable formula. The optimal process conditions are as follows: the proportions of HPMC, carrageenan, KCl and Tween 80 in the solvent (purified water) are 18% (m:V), 0.7% (m:V), 0.07% (m:V) and 0.018% (V:V), respectively. Under this condition, the viscosity of the resulting solution, glue solidification temperature and gel strength were medium. The resulting film has low hygroscopicity, good solubility, optical properties and mechanical properties. This research can provide data support for the precise formulation and industrial production of HPMC hollow plant capsules.

Core@shell PtAuAg@PtAg Hollow Nanodendrites as Effective Electrocatalysts for Methanol and Ethylene Glycol Oxidation.

Pt-based catalysts with core@shell structures are widely used in alcohol oxidations due to their excellent catalytic performance. In this work, we synthesized a series of core@shell PtAuAg@PtAg hollow nanodendrites (HNDs) with different compositions by a simple seed-mediated method. The PtAuAg@PtAg HNDs with a hollow core and dendritic shell exhibit excellent catalytic performance for ethylene glycol oxidation reaction (EGOR) and methanol oxidation reaction (MOR). Among these, Pt38Au29Ag33 HNDs have the highest mass activity (12364.0 mA mgPt-1/3278.0 mA mgPt-1) for EGOR and MOR, which is 4.2 times and 5.3 times higher than that of commercial Pt/C (2941.0 mA mgPt-1/617.6 mA mgPt-1), respectively. More importantly, after successive cyclic voltammetry tests, the retained mass activities of Pt38Au29Ag33 HNDs are 3913.8 mA mgPt-1 and 348.3 mA mgPt-1, which are much higher than that of commercial Pt/C as well. The excellent catalytic performance of PtAuAg@PtAg HNDs can be attributed to the structure of HNDs, which can greatly increase the surface area and active sites, as well as the electronic and synergistic effects among Pt, Au, and Ag. This research may provide new ideas for the development of high-efficiency hollow catalytic materials for EGOR and MOR.

Improving gas permeation performance of PDMS by incorporating hollow polyimide nanoparticles with microporous shells and preparing defect-free composite membranes for gas separation

Recently, various types of hollow materials have been added into polymer matrices to improve the gas permeation and separation performance of polymer materials. In this study, hollow polyimide (PI) nanoparticles with microporous shells were synthesized by interfacial polymerization between 4,4-(9-fluorenylidene)-dianiline and 1,2,4,5-benzenetetracarbonyl tetrachloride in the microemulsion. Free-standing polydimethylsiloxane (PDMS)/hollow PI nanoparticles mixed matrix membranes were prepared and the gas permeation-separation performance was investigated. The hollow and porous structure of the nanoparticles was well-preserved in membranes, which reduced the mass transport resistance. The permeability firstly increased and then decreased as the nanoparticle loading increased without sacrificing the permselectivity. Compared to the neat PMDS membranes with O2 and CO2 permeability of 786 and 3484 Barrer, respectively, the mixed matrix membranes with 3 wt% hollow PI nanoparticles achieved a O2 permeability up to 1664 Barrer accompanied with an O2/N2 permselectivity of 2.3 and a CO2 permeability up to 6639 Barrer accompanied with a CO2/N2 permselectivity of 9.1 at 35 °C and 0.2 MPa. Mixed-matrix composite membranes were fabricated by dip-coating the porous polyetherimide substrate into a PDMS solution with 3 wt% nanoparticles. The resultant defect-free mixed-matrix composite membrane showed excellent O2 and CO2 permeances of up to 1677 and 6502 GPU, respectively. The air separation measurement showed that the composite membranes could produce oxygen-enriched permeate stream enriched to ca. 30 vol%.