Gypsum-based Silica Gel Humidity-controlling Composite Materials:Preparation,Characterization,and Performance

Gypsum was used as substrate,and silica gel was mixed into substrate at a certain mass ratio to prepare humidity-controlling composites;moreover,the moisture absorption and desorption properties of gypsum-based composites were compared with adding different silica gel particle size and proportion.The morphological characteristics,the isothermal equilibrium moisture content curve,moisture absorption and desorption rate,moisture absorption and desorption stability,and humidity-conditioning performance were tested and analyzed.The experimental results show that,compared with pure-gypsum,the surface structure of the gypsum-based composites is relatively loose,the quantity,density and aperture of the pores in the structure increase.The absorption and desorption capacity increase along with the increase of silica gel particle size and silica gel proportion.When 3 mm silica gel particle size is added with a mass ratio of 40%,the maximum equilibrium moisture content of humidity-controlling composites is 0.161 g/g at 98% relative humidity(RH),3.22 times that of pure-gypsum.The moisture absorption and desorption rates are increased,the equilibrium moisture absorption and desorption rates are 2.68 times and 1.61 times that of pure-gypsum at 58.5% RH,respectively.The gypsum-based composites have a good stability,which has better timely response to dynamic humidity changes and can effectively regulate indoor humidity under natural conditions.

Photo-rechargeable batteries and supercapacitors:Critical roles of carbon-based functional materials

As a clean and renewable energy source,solar energy is a competitive alternative to replace conventional fossil fuels.Nevertheless,its serious fluctuating nature usually leads to a poor alignment with the actual energy demand.To solve this problem,the direct solar-to-electrochemical energy conversion and storage have been regarded as a feasible strategy.In this context,the development of high-performance integrated devices based on solar energy conversion parts(i.e.,solar cells or photoelectrodes)and electrochemical energy storage units(i.e.,rechargeable batteries or supercapacitors[SCs])has become increasingly necessary and urgent,in which carbon and carbon-based functional materials play a fundamental role in determining their energy conversion/storage performances.Herein,we summarize the latest progress on these integrated devices for solar electricity energy conversion and storage,with special emphasis on the critical role of carbon-based functional materials.First,principles of integrated devices are introduced,especially roles of carbon-based materials in these hybrid energy devices.Then,two major types of important integrated devices,including photovoltaic and photoelectrochemicalrechargeable batteries or SCs,are discussed in detail.Finally,key challenges and opportunities in the future development are also discussed.By this review,we hope to pave an avenue toward the development of stable and efficient devices for solar energy conversion and storage.

Specializing liquid electrolytes and carbon-based materials in EDLCs for low-temperature applications

Electric double-layer capacitors(EDLCs) are emerging technologies to meet the ever-increasing demand for sustainable energy storage devices and systems in the 21 st Century owing to their advantages such as long lifetime, fast charging speed and environmentally-friendly nature, which play a critical part in satisfying the demand of electronic devices and systems. Although it is generally accepted that EDLCs are suitable for working at low temperatures down to-40℃, there is a lack of comprehensive review to summarize the quantified performance of EDLCs when they are subjected to low-temperature environments. The rapid and growing demand for high-performance EDLCs for auxiliary power systems in the aeronautic and aerospace industries has triggered the urge to extend their operating temperature range,especially at temperatures below-40℃. This article presents an overview of EDLC’s performance and their challenges at extremely low temperatures including the capability of storing a considerable amount of electrical energy and maintaining long-term stability. The selection of electrolytes and electrode materials is crucial to the performance of EDLCs operating at a desired low-temperature range. Strategies to improve EDLC’s performance at extremely low temperatures are discussed, followed by the future perspectives to motivate more future studies to be conducted in this area.

Enhancing the cycling stability of Na-ion batteries by bonding MoS2 on assembled carbon-based materials

Room temperature Na-ion batteries(SIBs) show great potential for use as renewable energy storage systems.However, the large-scale application of SIBs has been hindered by the lack of an ideal SIBs anode material. We synthesized MoS2 on carbonized graphene-chitosan(G-C) using the hydrothermal method. The strong interaction between the MoS2 and the G-C greatly improved the electron transport rate and maintained the structural stability of the electrode, which lead to both an excellent rate capability and long cycle stability. The G-C monolith was proven to enhance the electrical conductivity of the composites and served as a matrix for uniformly dispersing active MoS2 nanosheets(NSs), as well as being a buffer material to adapt to changes in volume during the cycle.Serving as an anode material for SIBs, the MoS2-G-C electrode showed good cycling stability(527.3mAh g-1 at100 m A g-1 after 200 cycles), excellent rate capability, and a long cycle life(439.1 m Ah g-1 at 1 A g-1 after 200 cycles).

A New Type of Multielements-Doped,Carbon-based Materials Characterized by High-thermoconductiv-ity,Low Chemical Sputtering,Low RES Yield and Exposure to Plasma

Low-Z materials, such as carbon-based materials and Be, are major plasma-facing material (PFM) for current, even in future fusion devices. In this paper, a new type of multielement-doped carbon-based materials developed are presented along with experimental re-sults of their properties. The results indicate a decrease in chemical sputtering yield by one order of magnitude, a decrease in both thermal shock resistance and radiation-enhanced sublimation, an evidently lower temperature desorption spectrum, and combined properties of exposing to plasma.

Adsorption of rubidium ion from aqueous solution by surface ion imprinted materials

A new type of rubidium ion-imprinted polymer has been synthesized by the surface-imprinting technique using methacrylic acid as the functional monomer,the rubidium ion as the template,methanol as the solvent,and silica as a carrier.Ethylene glycol dimethacrylate and 2,2-azobisisobutyronitrile were used as acrosslinker and an initiator,respectively.In addition,based on the macrocyclic effect of crown ethers,the 18-crown-6 ligand was introduced as a ligand to fix the template ions better.Scanning electron microscopy,zeta-potential analysis,Fourier transform infrared spectroscopy,thermogravimetric analysis,and X-ray photoelectron spectroscopy were performed to characterize the ion-imprinted polymer.The effects of the preparation and adsorption conditions on the adsorption performance of the rubidium ion-imprinted polymer were investigated.The results indicated that the rubidium ion-imprinted polymer has high selectivity and faster kinetics than other adsorbents,with an equilibrium adsorption capacity of 200.19 mg·g^(-1)at 298 K within 25 min.The sorption isotherm was well described by the Freundlich isotherm model,while the adsorption kinetics fitted the pseudo-second-order kinetic model.Consecutive adsorption-desorption experiments showed that the ion-imprinted polymer had good chemical stability and reusability.

Adsorption and Adsorption-Photocatalytic Degradation of VOCs Based on Carbon Materials

Adsorption and the combination of adsorption and photocatalysis are prospective strategies for treating lowconcentrationvolatile organic compounds (VOCs). Behind the adsorption technology of VOC treatments are carbon-basedmaterials with large surface areas and high VOC uptake. This review summarizes the research progress in carbon-basedadsorbents and adsorbent-photocatalysts for VOC removal. Firstly, the VOC adsorption performances of various carbonmaterials, including activated carbon, activated carbon fiber, biochar, graphene and its derivatives, and carbon nanotubes,are summarized, and the adsorption mechanism of VOCs on carbon materials is analyzed. Then, the VOC adsorptionphotocatalyticproperties of composites comprised of different carbon materials and photocatalysts are presented. Finally,perspectives on the adsorption and adsorption-photocatalysis of VOCs via carbon materials are proposed. This reviewprovides an optimal reference for the research and development of adsorbents and adsorption-photocatalysts of VOCs.

SYNTHESIS OF MESOPOROUS POLY(STYRENE-co-MALEIC ANHYDRIDE)/SILICA HYBRID MATERIALS VIA A NONSURFACTANT-TEMPLATED SOL-GEL PROCESS

Mesoporous poly(styrene-co-maleic anhydride)/silica hybrid materials have been prepared. The synthesis was achieved by the HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and styrene-maleic anhydride copolymer in the presence of 3-aminopropyl triethoxysilane (APTES) as a coupling agent and citric acid as a nonsurfactant template or pore-forming agent, followed by ethanol extraction. Characterization results from nitrogen sorption isotherms and powder X-ray diffraction indicate that polymer-modified mesoporous materials with large specific surface areas (e.g. 900 m(2)/g) and pore volumes (e.g. 0.6 cm(3)/g) could be prepared. As the citric acid concentration is increased, the specific surface areas, pore volumes and pore diameters of the hybrid materials increase.

Structure Characterization and Dephosphorization Effect Analysis of Oyster Shell-silica Micropowder Waste Water Dephosphorization Materials

In this work,the effects of pH value of waste water and initial concentration of phosphorus on dephosphorization materials were investigated.The materials were prepared by shaping,sintering and hydrothermal reshaping oyster shell and silica micro-powder.Different concentrations of phosphorus-contained waste water were simulated with potassium dihydrogen phosphate solution,the effect of dephosphorization was tested with phosphomolybdenum blue spectrophotometer method,and the crystal phase and microstructure of materials were characterized by XRD and SEM methods. It was indicated that dephosphorization was completed in 6 h when the initial phosphorus concentration in waste water was lower than 15 mg/L, and the dephosphorization time prolonged as the increase of phosphorus concentration. It was observed that the pH value of waste water influenced dephosphorization significantly, and neutral subalkalic environment favored dephosphorization. When the pH value was 11, the efficiency of dephosphozation was the greatest. For waste water with an initial concentration of 20 mg/L, the dephosphozation rate is close to 100% in8 h.

Recent Advances in Carbon-Based Current Col lectors/Hosts for Alkali Metal Anodes

The urgent demand for high-energy-density storage systems evokes the research upsurge on the alkali metal batteries with high theoretical capacities.However,the utilization of alkali metal anodes,including Li,Na,and K,is significantly hindered by notorious dendrite growth,undesirable corrosion,and unstable solid electrolyte interface.In order to resolve these issues,the carbon materials for the rational design of current collector/host that can regulate the plating/stripping behavior of alkali metal have been exploited.These carbon-based current collectors/hosts are featured with many pivotal advantages,including mechanical integrity to accommodate the volume change,superior electronic/ionic conductivity,large available surface area,and rich functionalization chemistries to increase the affinity to alkali metal.In this review,the recent progress on various dimensional carbon-based current collectors/hosts with different chemical components in stabilizing the alkali metal anodes through the regulation of initial deposition and subsequent growth behavior during plating/stripping process is provided.The nanostructured carbon scaffolds with self-affinity to alkali metals,as well as the carbon frameworks with internal/external affinitive sites to alkali metals,catalogued by various dimensions,are discussed in this review.Therefore,these appealing strategies based on the carbon-based current collectors/hosts can provide a paradigm for the realization of high-energy-density alkali metal batteries.

Influence of Silica Fume on the Reflectivity and Transmission Efficiency of Cement-Based Materials

As a kind of mineral admixture, silica fume has low permittivity, which will affect the electromagnetic properties of cement-based materials. To study the effect of silica fume on the properties of cement-based materials, the reflectivity, transmission efficiency and pore structure were analyzed by using the vector network analyzer and mercury injection apparatus. Results show that silica fume can make the mortar more compact and the porosity of sample with 9% silica fume is only 17.8%, which is far lower than the control sample;With the increase of the silica fume content, the peak of reflectivity curve increases from -23.2 dB to -16.0 dB, and then decreases from -16.04 dB to -28.7 dB in the frequency range of 6 – 18 GHz. Reflectivity of sample with 3% content of silica fume is lower than other samples within 26.5 - 40 GHz;Transmission efficiency of samples shows the trend of increase with silica fume content increases from 0% to 6% within 8.2 - 12.4 GHz, 12 - 18 GHz and 26.5 - 40 GHz, but when the content increases from 6% to 9%, the transmission efficiency of samples reduces.

SYNTHESIS OF HYBRID MESOPOROUS POLYSTYRENE-SILICA MATERIALS WITH NON-SURFACTANT CITRIC ACID AS TEMPLATE VIA SOL-GEL PROCESS

Hybrid mesoporous polystyrene-silica materials were successfully prepared through HCl-catalyzed sol-gel reactions of tetraethyl orthosilicate (TEOS) and triethoxysilyl-functionalized polystyrene obtained via atom transfer radical polymerization (ATRP) of styrene, in the presence of citric acid (CA) as non-surfactant template or pore-forming agent and followed by ethanol extraction to remove template molecules. The materials were characterized by infrared spectroscopy OR), N-2 adsorption-desorption measurements, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The results indicate that the materials prepared with 50 wt%-60 wt% template contents have average pore sizes of 2-3 nm and large surface areas (ca. 886 m(2)/g) as well as high pore volumes (ca. 0.53 cm(3)/g). The mesoporosity arises from interconnected channels and pores with disordered arrangements. The pore diameters and pore volumes increase as the template content is increased. The pore diameters show a little change upon heating at 200degreesC overnight. However, the materials do not have good hydrothermal stability.

Preparation and Characterization of Mullite-Silica Aerogel Composite Material

Silica aerogel due to the high specific surface area, nanometer level pores and low density of the micro structure, had excellent heat-insulating properties. But the characteristics of silica aerogel with low density and high voidage resulted in poor mechanical properties. In order to improve the strength of materials and meet the actual needs, in this paper the heat-insulating composite material was made from the silica aerogel and mullite fiber. This kind of composite material mainly contented of mullite fiber, formed macro block structure, that gas gel is coated and filled with mullite fiber. Furthermore, the composite material had good strength and kept excellent thermal stability at 600°C. In addition the density of composite decreased with the increasing of the gas gel content.

Preparation of Magnesia Insulation Materials by Walnut Shell Powder Impregnated with Silica Sol

In order to reduce the thermal energy loss of high temperature kilns and furnaces and lower the surface temperature of the kiln body,magnesia insulation materials were prepared using self-made magnesia porous aggregates(using high purity magnesia powder as starting material and potassium oleate as the foaming agent),middle grade magnesia powder,calcium aluminate cement,and SiO_(2) micropowder as starting materials,introducing walnut shell powder impregnated with silica sol(short for Sws)as a pore-forming agent.The effects of the Sws addition(0,10%,15%,and 20%,by mass)and the sintering temperature(1300,1350,1400,and 1480℃)on the properties of magnesia insulation materials were studied.The results show that(1)for the specimens fired at 1480℃,when the Sws addition is 10%,the cold compressive strength is 22 MPa;when the Sws addition is 20%,the thermal conductivity is 0.368 W·m^(-1)·K^(-1)(350℃);(2)nano-silica in the silica sol reacts with MgO in the matrix to form forsterite,which encapsulates the pores volatilized from the walnut shell powder and forms closed pores.

Mechanism of E' center induced by γ ray radiation in silica optical fiber material

The characteristics of the best known defect centers E' in silica optical fiber material irradiated with ray were investigated by ESR at room temperature.A mechanism model of production of the E' center defect was established.The production of E' center includes two processes creation and activation.The strained bonds(or oxygen replacement) in silica networks lead to the creation of new defects whose concentration increases linearly with the dose.The pre-existing defects produce the activation,which tends to saturation.According to this model,the relation of E' center concentration changing with irradiation dose was obtained theoretically.The results are in good agreement with the experimental results.

High specific surface area porous graphene grids carbon as anode materials for sodium ion batteries

Although great accomplishments of functional material synthesis have been achieved in sodium ion batteries(SIBs)recently,there are still numerous challenges and problems in preparing carbon-based materials with porous architectures and enough lattice distance for Na^+insertion.Herein we report a templated strategy to synthesize 3D porous graphene girds(PGGs)consisting of several stacking graphene structure with ultrahigh surface area and hierarchical connected structure by employing Ag nanoparticles(NPs).The Ag NPs will regenerate for decreasing the experimental cost,also in line with principles of green chemistry and environmentally friendly strategy.The PGGs obtain advanced specific capacity of160 m A h g^(-1)at current density of 50 m A h g^(-1).Moreover,112 mA h g^(-1)capacity can be gained at 1 A h g^(-1)during 1000 cycles.Due to their porous architecture,ultrahigh surface area and low amorphous graphited structure,PGGs electrode showed the excellent electrochemical performance in high rate capability.

Preparation of Nanoporous Thermal Insulating Materials and Their Application as Ladle Linings

The nanoporous thermal insulating material was prepared by using fumed silica,SiC powder and glass fiber as starting materials,the appropriate thickness of the nanoporous thermal insulating material lined in ladle was discussed by the simulation method,and the effect of its application as ladle lining was investigated.The results show that the thermal conductivity of the nanoporous thermal insulating material prepared in composition of fumed silica： SiC powder： glass fiber =75： 20：5 （in mass） is 0.023 W · m^-1 · K^-1 at 1 000 ℃,the appropriate thickness of the nanoporous thermal insulating material lined in ladle is ≤ 5 mm and the average temperature of the ladle outside surface when lined with the nanoporous thermal insulating material is 95 ℃ lower than that with the ordinary thermal insulating material.

Porous 3D carbon-based materials:An emerging platform for efficient hydrogen production

Due to their unique properties and uninterrupted breakthrough in a myriad of clean energy-related applications,carbon-based materials have received great interest.However,the low selectivity and poor conductivity are two primary difficulties of traditional carbon-based materials(zero-dimensional(0D)/one-dimensional(1D)/two-dimensional(2D)),enerating inefficient hydrogen production and impeding the future commercialization of carbon-based materials.To improve hydrogen production,attempts are made to enlarge the surface area of porous three-dimensional(3D)carbon-based materials,achieve uniform interconnected porous channels,and enhance their stability,especially under extreme conditions.In this review,the structural advantages and performance improvements of porous carbon nanotubes(CNTs),g-C_(3)N_(4),covalent organic frameworks(COFs),metal-organic frameworks(MOFs),MXenes,and biomass-derived carbon-based materials are firstly summarized,followed by discussing the mechanisms involved and assessing the performance of the main hydrogen production methods.These include,for example,photo/electrocatalytic hydrogen production,release from methanolysis of sodium borohydride,methane decomposition,and pyrolysis-gasification.The role that the active sites of porous carbon-based materials play in promoting charge transport,and enhancing electrical conductivity and stability,in a hydrogen production process is discussed.The current challenges and future directions are also discussed to provide guidelines for the development of next-generation high-efficiency hydrogen 3D porous carbon-based materials prospected.

Study and Application of Sealing Material for Coke Oven Chamber

A kind of dry refractory sealing material has been developed to repair the fine cracks in coke oven chamber. With silica sand as the main raw material, the sealing material is blown into coke oven chamber by compressed air while being applied, and bonded to brick surface or filled in fine cracks of chamber under right pressure. The physical properties of the material are similar to those of silica bricks during its application. So it can be adapted to conditions of coke oven and has good service life. The study and application results of the sealing material are described in this paper.

MODIFICATION THE CEMENTIOUS MATERIAL OF ULTRA-HIGH-STRENGTH SLEEPER CONCRETE

This paper presents investigation results on the natural ultra-fine mineral flour of crystalline silica fume (CSF) and porous quartz sand stone (PQSS) which can modify cement mortar strength under hydrothermal synthesis reaction (HSR) in the autoclave-cured condition. The replacement of cement by CSF and PQSS can signifi cantly increase the Jflerural and compressive strength which reach 22MPa and 150MPa respectively and de-crease the porosity oj the cement mortar. The ratio oj fine aggregation, standard sand to cementions material has sig nificant influence on the mortar strength. The mechanisms involved in cement and natural mineral flour and the HSR are presented. CaO/SiO2 ratio ranges from 3. 20 to 1. 11. the main hydrate phase is C2SH and there is not Tober-morite through X-Ray diffraction qualitative analysis. The new and ultra-high strength cementious material as basic material of sleeper concrete can he used in prestressed reinforcement sleeper concrete.