Designing xerogels at the molecular level to overcome volume shrinkage is a promising strategy for carbon xerogels with desirable structure and performance.Here,we design a xerogel with non-shrinkage by introducing Zn...Designing xerogels at the molecular level to overcome volume shrinkage is a promising strategy for carbon xerogels with desirable structure and performance.Here,we design a xerogel with non-shrinkage by introducing ZnCl_(2) into resorcinol-melamine-formaldehyde polymerization.The gel network consisting of micrometer pores and large particles(0.26-1.35μm)is constructed by the coordination of Zn^(2+) with oxygen/nitrogen-containing groups,which is attributed to the structural support of the rigid triazine skeleton with large steric hindrance.Therefore,the reinforced gel network possesses enough strength to withstand capillary forces during atmospheric drying,and special drying and solvent exchange are avoided.The xerogels show non-shrinkage and a short preparation time of 24 h.The resulted activated carbon xerogels with interconnected hierarchically micro-meso-macropores exhibit an optimal specific surface area of 1520 m^(2)/g(through xerogels pyrolysis and the pore-forming of ZnCl_(2)),high adsorption(methylene blue,I-,Cu^(2+),etc.),and repeated adsorption ability.This work provides novel thought for porous nanomaterials with non-shrinkage and desirable structures in adsorption and energy storage.展开更多
Obtaining large specific surface areas(SSA)for carbon xerogels poses a significant challenge due to the inevitable volume shrinkage of xerogel.Here,the Zn^(2+) coordination-catalyzed in-situ polymerization approach wa...Obtaining large specific surface areas(SSA)for carbon xerogels poses a significant challenge due to the inevitable volume shrinkage of xerogel.Here,the Zn^(2+) coordination-catalyzed in-situ polymerization approach was proposed to fabricate xerogels with a low shrinkage of 13.03% and a short preparation period of 24 h.In resorcinolformaldehyde(RF)polymerization,ZnCl_(2) could accelerate the reaction kinetics through the coordination of the Zn^(2+) and hydroxyl groups.The gel network with adjustable RF particles(46.5 nm-1.89μm)and narrow neck structures was constructed by changing ZnCl_(2) and ethanol contents,which could resist volume shrinkage during atmospheric drying without solvent exchange.The activated carbon xerogels(ACXs)with hierarchical structure were designed by one-step carbonization/activation due to the pore-forming of ZnCl_(2).The obtained ACXs showed a large SSA of 1689 m^(2)/g,multi-dyes adsorption capacity(methylene blue,Congo red,methyl orange,and Sudan Ⅲ were 625.90,359.46,320.69,and 453.92 mg/g,respectively),and reusability of 100%.The maximum monolayer MB adsorption capacity was 630.28 mg/g.This work presents an efficient strategy to design porous nanomaterials with low shrinkage and large SSA,which illustrates promising applications in separation,adsorption,and photoelectric catalysis.展开更多
Self-healing(SH)polymer composites are a transformative achievement in polymer material technology that offers significant potential to extend the lifespan and reliability of materials.This work presents a novel appro...Self-healing(SH)polymer composites are a transformative achievement in polymer material technology that offers significant potential to extend the lifespan and reliability of materials.This work presents a novel approach to developing a hybrid natural-synthetic reinforced polymer composite with SH behavior using urea-free,non-toxic,environment-friendly material encapsulating resin,and hardener within a multicavity microcapsule(MC).This MC offers multiple healing because of its multicavity structure.These Xerogel MCs are integrated into hybrid bamboo/recycled glass fiber reinforced epoxy composite(25 wt% and 40 wt%)and were evaluated for their flexural strength,healing efficiency,moisture absorption,and thermal behavior.The results demonstrated that the composite containing 40 wt% exhibited the highest initial flexural strength and modulus retention after multiple healing cycles,approaching 80.67% and 61.34% respectively at 1st and 2nd cycles of healing efficiency.The behavior of self-healing hybrid composites(SHHC)in different environmental conditions was also investigated.Thermal Analysis TGA and DTA done on hybrid and other SH composites.Scanning electron microscopy shows the surface morphology of Xerogel MCs before and after damage,composite fractured surface,and how Healing Agent(HA)gets released and acquires surface after fracture.To ensure functional groups and chemical reactions between each component of the composite,FTIR analysis confirmed the successful encapsulation of HA inside MC.展开更多
TiO_2 nanoparticles(NPs)were prepared via the hydrothermal route of TiO_2 xerogel in nitric acid, hydrochloric acid and acetic acid. The physico-chemical properties of the powders were characterized by X-ray diffracti...TiO_2 nanoparticles(NPs)were prepared via the hydrothermal route of TiO_2 xerogel in nitric acid, hydrochloric acid and acetic acid. The physico-chemical properties of the powders were characterized by X-ray diffraction(XRD)and N_2 adsorption desorption techniques. The effects of the different acids on the structure(crystal phase)and texture(primary particle size and porosity)of the TiO_2 powders were explored. Results indicated that acetic acid facilitated the formation and stability of pure anatase phase. On the other hand, nitric acid and hydrochloric acid led to the transformation from anatase to rutile. The catalyst synthesized via the hydrothermal route of TiO_2 xerogel in the low concentration hydrochloric acid solution(Ti-HCl-0.15)had the highest photocatalytic activity than the catalysts obtained in the other two acid solutions. The effects of the different acids were discussed in terms of acid strength, chelating effect and the thermal stability of the adsorbed acidic anions.展开更多
Micro/nanostructured SiOx/C composite was firstly synthesized by carbothermal reduction of silica-carbon binary xerogel.The homogeneous dispersion feature of the two components in binary xerogel contributes to effecti...Micro/nanostructured SiOx/C composite was firstly synthesized by carbothermal reduction of silica-carbon binary xerogel.The homogeneous dispersion feature of the two components in binary xerogel contributes to effectively carbothermally reduce the O/Si atomic ratio,enhancing the electrochemical activity of the SiOx component.The micron-sized SiOx/C spheres are composed of many near-spherical nanoparticles.The synthesized SiOx/C exhibits a stable and high reversible capacity of 830 m A·h·g^-1 for 100 cycles,and excellent rate-capability.The homogeneous dispersion structure of phases,the micro/nanostructure and the high electrochemical activity of SiOx component combinedly contribute the excellent electrochemical performance.展开更多
Fe_(3)O_(4)magnetic xerogel composites were prepared by polycondensation of resorcinol(R)-formaldehyde reaction via a sol-gel process in an aqueous solution through varying the molar ratio of Fe_(3)O_(4)nanoparticles(...Fe_(3)O_(4)magnetic xerogel composites were prepared by polycondensation of resorcinol(R)-formaldehyde reaction via a sol-gel process in an aqueous solution through varying the molar ratio of Fe_(3)O_(4)nanoparticles(MNPs),catalyst(C),and water(W)content.MNPs were obtained by co-precipitation(MC),oxidation of iron salts(MO),or solvothermal synthesis(MS).Both MNPs and magnetic xerogels were examined regarding the performance of arsenic and fluoride removal in a batch system.The MC-based MNPs had higher adsorption capacities for both fluoride(202.9 mg/g)and arsenic(3.2 mg/g)than other MNPs in optimum conditions.The X-ray diffraction,Fourier transform infrared spectroscopy,and energy-dispersive X-ray spectroscopy confirmed that Fe was composed into the polymeric matrix of magnetic xerogels that contained 0.59%-4.42%of Fe with a molar ratio of MNPs(M)to R between 0.01 and 0.10.With low R/C and optimum M/R ratios,an increase in the surface area of magnetic xerogels affected the fluoride and arsenic adsorption capacities.The magnetic xerogel composites with the MC-based MNPs prepared at a fixed R/C ratio(100)and at different R/W(0.05-0.06)and M/R(0.07-0.10)ratios had a high arsenic removal efficiency of 100%at an As(V)concentration of 0.1 mg/L and pH of 3.0.The maximum adsorption capacities of magnetic xerogels were approximately five times higher than those of the xerogels without MNP composites.Therefore,Fe_(3)O_(4)nanoparticles enhanced the adsorption of arsenate and fluoride.The variations of alkaline catalyst and water content significantly affected the resulting properties of textural and surface chemistry of magnetic xerogel composites.展开更多
The synthesis and properties of carbon xerogels are briefly described in this mini-review, emphasizing the methods used for tuning their surface chemistry and textural properties in order to design efficient electroca...The synthesis and properties of carbon xerogels are briefly described in this mini-review, emphasizing the methods used for tuning their surface chemistry and textural properties in order to design efficient electrocatalysts for fuel cells. In particular, the role played by the surface functional groups in determining the loading, dispersion, oxidation state and stability of the metal phases is addressed.展开更多
Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide...Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide xerogel films was simulated with an equivalent circuit model, which was derived from the mechanism of electrode reactions. Measured electrochemical impedance spectra at various electrode potentials were analyzed by using the complex non-linear least-squares fitting method. The results show that impedance spectra consist of 2 high-to- medium frequency depressed arcs and a low frequency straight line. The high frequency arc is attributed to the absorption reaction of lithium ions into the oxide film, the medium frequency arc is attributed to the charge transfer reaction at the vanadium oxide/electrolyte interface and the low frequency is characterized by a straight line with a phase angle of 45° corresponding to the diffusion of lithium ion through vanadium oxide phase. The experimental and calculated results are compared and discussed focusing on the electrochemical performance and the state of charge of the electrode. Moreover, the high consistence of the fitted values of the model to the experimental data indicates that this mathematical model does give a satisfying description of the intercalation process of vanadium pentoxide xerogel films.展开更多
The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigat...The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigated by cyclic voltammograms,UV-visible spectral transmittance and XPS.The results show that the cycling efficiency and the reversibility of insertion/extraction of Li + ions in (PEO) 1MoO 3·nH 2O nanocomposite film were improved.The intercalation of PEO into MoO 3 xerogel modulated the wavelength range of electrochromism and enhanced the electrochromic efficiency.Two different chemical conditions of Li + ions existing in the interlayer and interstitial positions of MoO 3 lattice were observed in MoO 3 xerogel and (PEO) 1MoO 3·nH 2O nanocomposite films.展开更多
The catalytically assisted self-propagating high-temperature synthesis of carbon fibrous nanostructures, where the iron-doped colloidal carbon xerogel is proposed as a catalyst system, was examined. The carbon xerogel...The catalytically assisted self-propagating high-temperature synthesis of carbon fibrous nanostructures, where the iron-doped colloidal carbon xerogel is proposed as a catalyst system, was examined. The carbon xerogel was prepared through carbonization of an iron doped organic xerogel at temperatures ranging from 600 to 1050℃. The reaction between calcium carbide and hexachloroethane in the presence of sodium azide is exothermic enough to proceed at a high temperature, self-sustaining regime. The combustion reactions of those mixtures enriched with iron-doped carbon xerogels were conducted in a stainless steel reactor---calorimetric bomb under an initial pressure of 1 MPa of argon. Scanning electron microscopy analysis of the combustion products revealed low yield of various type of carbon fibers （presumably nanotubes）, which grew via the tip-growth mechanism. The fibrous nanostructures were found in the vicinity of the spot of ignition, while in the outer and cooler area of the reactor, dusty products with soot-like morphology dominated. No significant correlation between the pyrolysis temperature of the carbon xerogel and the morphology of the obtained carbon fibrous nanostructures was observed.展开更多
A new blue photoluminescent material, a mixed tin and manganese oxide xerogel, is prepared via sol-hydrothermalgel process assisted by citric acid. The composition xerogel exhibits strong blue emission at room tempera...A new blue photoluminescent material, a mixed tin and manganese oxide xerogel, is prepared via sol-hydrothermalgel process assisted by citric acid. The composition xerogel exhibits strong blue emission at room temperature, with an emission maximum at 434 nm under short （234 nm） or long-wavelength （343 nm） ultraviolet excitation. The photoluminescent excitation spectrum of the mixed tin and manganese oxide xerogel, monitored at an intensity maximum wavelength of 434 nm of the emission, consists of two excitation peaks at 234 nm and 343 am. With heat treatment temperature increasing from 110 ℃ to 200 ℃, the blue emission intensity increases remarkably, whereas it is almost completely quenched after being treated at 300 ℃. The carbon impurities in the mixed tin and manganese oxide xerogel, confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, should be responsible for the bright blue photoluminescence.展开更多
The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V2O5 xero-gel in sol-gel. The synthesis and state of the films are investigated by the XRD, IR, SEM, etc. The results show that V2O5...The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V2O5 xero-gel in sol-gel. The synthesis and state of the films are investigated by the XRD, IR, SEM, etc. The results show that V2O5, xerogel is a layered structure which arranges in c-direction. The mterlayer distance of V2O5 xerogel increases remarkably when PEO is intercalated in V2O5 xero-gel interlayer. PEO has strong interaction with V2O5 host. The surface of the films is homogeneous without holes and cracks.展开更多
The V 2O 5 sol was fabricated by ultra fast quenching.The vanadium with low valence (V 4+ ) was found in V 2O 5 xerogel films by XPS analysis.The technology of oxygen top blown was applied to analyze the XPS...The V 2O 5 sol was fabricated by ultra fast quenching.The vanadium with low valence (V 4+ ) was found in V 2O 5 xerogel films by XPS analysis.The technology of oxygen top blown was applied to analyze the XPS spectrum difference of V 2O 5 xerogel when the powder of V 2O 5 was melting in air or in oxygen atmosphere.The results show that the different melting atmosphere has certain influences on the chemical valence of V 2O 5 xerogel.展开更多
This paper aims to create visible light driven ternary photocatalysts using zinc oxide(ZnO),cerium(IV)oxide(CeO_(2)),and carbon xerogel(CX) as constituent materials.The use of CeO_(2) is based on the creation of direc...This paper aims to create visible light driven ternary photocatalysts using zinc oxide(ZnO),cerium(IV)oxide(CeO_(2)),and carbon xerogel(CX) as constituent materials.The use of CeO_(2) is based on the creation of direct-Z-scheme heterojunctions with the ZnO and the consequent diminishing of charge recombination,whereas the carbon xerogel inclusion is predicted to minimize bandgap energy,decrease electro n-hole reco mbination,and boost specific surface area.Furthermo re,the choice of the black-wattle tannin as a carbonaceous precursor was targeted at the development of an environmentally friendly and affordable composite.The existence of the hexagonal phase of zinc oxide and cubic structure of the cerium(IV) oxide in the ternary material was confirmed by X-ray diffractometry and X-ray photoelectron spectroscopy,with the latter also suggesting chemical bonding between the ZnO and the CX due to the creation of zinc oxycarbide complexes.The inclusion of the carbon xerogel provokes a significant modification in the morphology of the ternary material,resulting in an increased surface area and smaller particle aggregates.The CX/ZnO-CeO_(2) ternary composite obtains the highest photocatalytic efficiency among all the materials studied,degrading 100% of 4-chlorophenol under simulated sunlight and 68% under visible radiation,after 5 h.The increased photocatalytic activity can be attributed to the formation of direct Z-scheme heterojunctions between the semiconductors,higher visible light response,and higher specific surface area,as evidenced by the results obtained by active radical scavenging,chronoamperometry,diffuse reflectance spectroscopy,and N_(2) adsorption-desorption isotherms.展开更多
Mesoporous polyethylene glycol-resorcinol and formaldehyde（PEG-RF） carbon xerogels were prepared by a new polymer blend method in which PEG-RF mixed organic xerogels were synthesized by blending thermally unstable p...Mesoporous polyethylene glycol-resorcinol and formaldehyde（PEG-RF） carbon xerogels were prepared by a new polymer blend method in which PEG-RF mixed organic xerogels were synthesized by blending thermally unstable polyethylene glycol with organic monomers, resorcinol and formaldehyde and then subjected to pyrolization at 1 000 ℃. The influences of mass ratio of PEG to the theoretical yield of RF xerogel, m（PEG）/m（RF） and the （relative） molecular mass of PEG on the pore structure and electric double layer capacitance（EDLC） performance of PEG-RF carbon xerogels were investigated. The results show that PEG under different conditions leads to the difference of phase separation structure of the polymer blend and thus the change of pore structure of PEG-RF carbon xerogels. Specific surface area and capacity of PEG-RF carbon xerogels in 30% H2SO4 solution can reach （755 m2/g） and 150 F/g, respectively. Their surface can be fully utilized to form electric double layer. However, the pore structure differences of PEG-RF carbon xerogels result in their different EDLC performances. The distributed capacitance effect increases with decreasing the pore size of PEG-RF carbon xerogels.展开更多
Vanadium pentoxide xerogel（VXG） films were prepared by rapid quenching, then corn type 2016 size lithium rechargeable batteries were assembled and tested with the VXG film electrodes and lithium anodes. Electrochemi...Vanadium pentoxide xerogel（VXG） films were prepared by rapid quenching, then corn type 2016 size lithium rechargeable batteries were assembled and tested with the VXG film electrodes and lithium anodes. Electrochemical impedance spectroscopy（EIS） analysis result reveals the expected response for intercalation, except that there is almost no Warburg （diffusion） component. Analyses results of cyclic voltammetry（CV）, constant discharge （CD） and discharge-charge（DC） indicate that the sample achieves a high initial discharge specific capacity of approximate 400 mA·h/g and a corresponding efficiency of 97 % in the voltage diapason of 1.5 - 4.0 V with a draining current of 60 mA/g. Its preservation ratio of capacity still keeps as high as 85 % even after 100 cycles. The good electrochemical performance indicates that VXG film material is a promising cathode for lithium rechargeable batteries.展开更多
The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA ...The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA microcapsules （TOA-MCs） were examined using DM, SEM/EDS and EPMA. The adsorption and elution properties of Au（III） were studied by the column method using spherical and highly porous TOA-MCs. The uptake properties of precious metals （Au（IIl）, Pt（IV）, and Pd（II）） were examined by the batch method using TOA-MCs in different concentrations of hydrochloric acid （HCI） solution. The order of uptake （%） of the precious metals was Au（III） 〉 Pt（IV） 〉 Pd（II）. TOA-MCs have strong affinity towards Au（III） in HCI solution. The uptake （%） of Au（III） by TOA-MCs was estimated to be -100% and equilibrium was attained within 1 hour. The breakthrough and elution behaviors of Au（III） were examined by varying the Au（III） concentration in the feed, flow rate, reaction temperature, and eluent concentration. The Au（IlI） in 1 M HCI solution was effectively extracted with TOA-MCs in the column operation. The breakthrough curve showed the S-shaped profile and no dislodgement of TOA from the matrices of CaALG. The breakthrough curve rose steeply and the uptake of Au（IIl） was fairly fast, which indicated a relatively high uptake rate of Au（III） in TOA-MCs. The break point （5% breakthrough） and breakthrough capacity （B. T. Capacity） were estimated to be 82 cm3 and 0.60 mmol/g, respectively. The total capacity （T. capacity） was estimated to be 1.30 mmol/g, which was considerably larger than those of conventional resins. The elution properties of Au（Ill） were studied by varying the concentration of thiourea （0.025 M-1 M） in 1 M HC1 solution. The retention volume （VR, cm3） tended to decrease with the increase in thiourea （TU） concentration. The loaded Au（III） ions were successfully eluted （- 100%, total elution percentage） by the eluent of TU （0.5 M） in HC1 （1 M） solution. The alginate gel microcapsules enclosing TOA extractant were thus effective for the selective separation and recovery of Au（IIl） ions in HCI solution.展开更多
In the present study, sol-gel process is used to synthesize P-doped TiO2 xerogels by the cogelation method of a functionalized P alkoxide, (NH2-(CH2)2-NH-(CH2)2-P(O)-(OC2H5)2) with Ti(OC3H7)4 in either 2-methoxyethano...In the present study, sol-gel process is used to synthesize P-doped TiO2 xerogels by the cogelation method of a functionalized P alkoxide, (NH2-(CH2)2-NH-(CH2)2-P(O)-(OC2H5)2) with Ti(OC3H7)4 in either 2-methoxyethanol or isopropanol. The phosphorus-doping improved the thermal stability of titania and decreased the phase transformation of anatase into rutile. This modification by phosphorus shifted the absorption edge of titania to the visible region as proved by Diffuse reflectance measurements, and thus offers the possibility to produce visible light effective TiO2 photocatalyst. The excellent photocatalytic activity of P-doped TiO2 xerogels compared to pure TiO2 could be explained by its high surface area and small TiO2-anatase crystallite size. From these results, it was proved by using three different models that phosphorus intrinsically influences the photocatalytic activity.展开更多
Small angle X-ray scattering (SAXS) with synchrotron radiation as X-ray source has been used to study the structure of silica xerogels prepared by sol-gel process. Both the agreement of SAXS profiles with and the devi...Small angle X-ray scattering (SAXS) with synchrotron radiation as X-ray source has been used to study the structure of silica xerogels prepared by sol-gel process. Both the agreement of SAXS profiles with and the deviation from Porod’s law and Debye’s theory have been found, showing that there are differences between the structures of these xerogels. The specific surfaces of the samples whose SAXS profiles agreed with Porod’s law and Debye’s theory have been determined by analyzing SAXS data according to the methods of Porod and Debye, respectively, and the results of both methods used were found to be similar. We have proposed the corresponding Porod and Debye analysis methods to determine the specific surfaces of samples whose SAXS profiles do not agree with Porod’s law and Debye’s theory, i.e. the negative or positive deviation. The results of both methods used here were also found to be close to each other. The specific surfaces fell between approximately 80-150 m2/cm3 for the samples prepared展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFB3711501)the Shanghai Industrial Collaborative Innovation Leading Group Office(No.XTCX-KJ-2023-53)+3 种基金the Fundamental Research Funds for the Central Universities(No.23D110609)the Open Research Fund of Songshan Lake Materials Laboratory(No.2022SLABFN09)the Foundation of State Key Laboratory of Biobased Material and Green Paper-making,Qilu University of Technology,Shandong Academy of Sciences(No.GZKF202231)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-d-2022012).
文摘Designing xerogels at the molecular level to overcome volume shrinkage is a promising strategy for carbon xerogels with desirable structure and performance.Here,we design a xerogel with non-shrinkage by introducing ZnCl_(2) into resorcinol-melamine-formaldehyde polymerization.The gel network consisting of micrometer pores and large particles(0.26-1.35μm)is constructed by the coordination of Zn^(2+) with oxygen/nitrogen-containing groups,which is attributed to the structural support of the rigid triazine skeleton with large steric hindrance.Therefore,the reinforced gel network possesses enough strength to withstand capillary forces during atmospheric drying,and special drying and solvent exchange are avoided.The xerogels show non-shrinkage and a short preparation time of 24 h.The resulted activated carbon xerogels with interconnected hierarchically micro-meso-macropores exhibit an optimal specific surface area of 1520 m^(2)/g(through xerogels pyrolysis and the pore-forming of ZnCl_(2)),high adsorption(methylene blue,I-,Cu^(2+),etc.),and repeated adsorption ability.This work provides novel thought for porous nanomaterials with non-shrinkage and desirable structures in adsorption and energy storage.
基金supported by the National Key Research and Development Program of China(No.2023YFB3711501)Shanghai Industrial Collaborative Innovation Leading Group Office(No.XTCX-KJ-2023-53)+3 种基金the Fundamental Research Funds for the Central Universities(No.23D110609)the Open Research Fund of Songshan Lake Materials Laboratory(No.2022SLABFN09)the Foundation of State Key Laboratory of Biobased Material and Green Papermaking,Qilu University of Technology,Shandong Academy of Sciences(No.GZKF202231)the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-D-2022012).
文摘Obtaining large specific surface areas(SSA)for carbon xerogels poses a significant challenge due to the inevitable volume shrinkage of xerogel.Here,the Zn^(2+) coordination-catalyzed in-situ polymerization approach was proposed to fabricate xerogels with a low shrinkage of 13.03% and a short preparation period of 24 h.In resorcinolformaldehyde(RF)polymerization,ZnCl_(2) could accelerate the reaction kinetics through the coordination of the Zn^(2+) and hydroxyl groups.The gel network with adjustable RF particles(46.5 nm-1.89μm)and narrow neck structures was constructed by changing ZnCl_(2) and ethanol contents,which could resist volume shrinkage during atmospheric drying without solvent exchange.The activated carbon xerogels(ACXs)with hierarchical structure were designed by one-step carbonization/activation due to the pore-forming of ZnCl_(2).The obtained ACXs showed a large SSA of 1689 m^(2)/g,multi-dyes adsorption capacity(methylene blue,Congo red,methyl orange,and Sudan Ⅲ were 625.90,359.46,320.69,and 453.92 mg/g,respectively),and reusability of 100%.The maximum monolayer MB adsorption capacity was 630.28 mg/g.This work presents an efficient strategy to design porous nanomaterials with low shrinkage and large SSA,which illustrates promising applications in separation,adsorption,and photoelectric catalysis.
文摘Self-healing(SH)polymer composites are a transformative achievement in polymer material technology that offers significant potential to extend the lifespan and reliability of materials.This work presents a novel approach to developing a hybrid natural-synthetic reinforced polymer composite with SH behavior using urea-free,non-toxic,environment-friendly material encapsulating resin,and hardener within a multicavity microcapsule(MC).This MC offers multiple healing because of its multicavity structure.These Xerogel MCs are integrated into hybrid bamboo/recycled glass fiber reinforced epoxy composite(25 wt% and 40 wt%)and were evaluated for their flexural strength,healing efficiency,moisture absorption,and thermal behavior.The results demonstrated that the composite containing 40 wt% exhibited the highest initial flexural strength and modulus retention after multiple healing cycles,approaching 80.67% and 61.34% respectively at 1st and 2nd cycles of healing efficiency.The behavior of self-healing hybrid composites(SHHC)in different environmental conditions was also investigated.Thermal Analysis TGA and DTA done on hybrid and other SH composites.Scanning electron microscopy shows the surface morphology of Xerogel MCs before and after damage,composite fractured surface,and how Healing Agent(HA)gets released and acquires surface after fracture.To ensure functional groups and chemical reactions between each component of the composite,FTIR analysis confirmed the successful encapsulation of HA inside MC.
基金Supported by the National Basic Research Program of China("973"Program,No.2014CB239300,No.2012CB720100)National Natural Science Foundation of China(No.21406164,No.21466035)
文摘TiO_2 nanoparticles(NPs)were prepared via the hydrothermal route of TiO_2 xerogel in nitric acid, hydrochloric acid and acetic acid. The physico-chemical properties of the powders were characterized by X-ray diffraction(XRD)and N_2 adsorption desorption techniques. The effects of the different acids on the structure(crystal phase)and texture(primary particle size and porosity)of the TiO_2 powders were explored. Results indicated that acetic acid facilitated the formation and stability of pure anatase phase. On the other hand, nitric acid and hydrochloric acid led to the transformation from anatase to rutile. The catalyst synthesized via the hydrothermal route of TiO_2 xerogel in the low concentration hydrochloric acid solution(Ti-HCl-0.15)had the highest photocatalytic activity than the catalysts obtained in the other two acid solutions. The effects of the different acids were discussed in terms of acid strength, chelating effect and the thermal stability of the adsorbed acidic anions.
基金supported by the National Natural Science Foundation of China(51602313 and 51764008)Science and Technology Project of Guizhou Province(Qiankehe No.2016,7439).
文摘Micro/nanostructured SiOx/C composite was firstly synthesized by carbothermal reduction of silica-carbon binary xerogel.The homogeneous dispersion feature of the two components in binary xerogel contributes to effectively carbothermally reduce the O/Si atomic ratio,enhancing the electrochemical activity of the SiOx component.The micron-sized SiOx/C spheres are composed of many near-spherical nanoparticles.The synthesized SiOx/C exhibits a stable and high reversible capacity of 830 m A·h·g^-1 for 100 cycles,and excellent rate-capability.The homogeneous dispersion structure of phases,the micro/nanostructure and the high electrochemical activity of SiOx component combinedly contribute the excellent electrochemical performance.
基金supported by the Mexican Institute of Water Technology(Grant No.DP2101.1)the Catedras-CONACyT Program of the National Council of Science and Technology(Project No.159).
文摘Fe_(3)O_(4)magnetic xerogel composites were prepared by polycondensation of resorcinol(R)-formaldehyde reaction via a sol-gel process in an aqueous solution through varying the molar ratio of Fe_(3)O_(4)nanoparticles(MNPs),catalyst(C),and water(W)content.MNPs were obtained by co-precipitation(MC),oxidation of iron salts(MO),or solvothermal synthesis(MS).Both MNPs and magnetic xerogels were examined regarding the performance of arsenic and fluoride removal in a batch system.The MC-based MNPs had higher adsorption capacities for both fluoride(202.9 mg/g)and arsenic(3.2 mg/g)than other MNPs in optimum conditions.The X-ray diffraction,Fourier transform infrared spectroscopy,and energy-dispersive X-ray spectroscopy confirmed that Fe was composed into the polymeric matrix of magnetic xerogels that contained 0.59%-4.42%of Fe with a molar ratio of MNPs(M)to R between 0.01 and 0.10.With low R/C and optimum M/R ratios,an increase in the surface area of magnetic xerogels affected the fluoride and arsenic adsorption capacities.The magnetic xerogel composites with the MC-based MNPs prepared at a fixed R/C ratio(100)and at different R/W(0.05-0.06)and M/R(0.07-0.10)ratios had a high arsenic removal efficiency of 100%at an As(V)concentration of 0.1 mg/L and pH of 3.0.The maximum adsorption capacities of magnetic xerogels were approximately five times higher than those of the xerogels without MNP composites.Therefore,Fe_(3)O_(4)nanoparticles enhanced the adsorption of arsenate and fluoride.The variations of alkaline catalyst and water content significantly affected the resulting properties of textural and surface chemistry of magnetic xerogel composites.
基金supported by project PEstC/EQB/LA0020/2011 financed by FEDER through COMPETE-Programa Operacional Factores de CompetitividadeFCT-Fundao para a Ciência e a Tecnologia
文摘The synthesis and properties of carbon xerogels are briefly described in this mini-review, emphasizing the methods used for tuning their surface chemistry and textural properties in order to design efficient electrocatalysts for fuel cells. In particular, the role played by the surface functional groups in determining the loading, dispersion, oxidation state and stability of the metal phases is addressed.
文摘Vanadium pentoxide xerogel films used for lithium rechargeable batteries were prepared from crystalline c-V2O5 by melt quenching method,then the electrochemical process of lithium intercalation into vanadium pentoxide xerogel films was simulated with an equivalent circuit model, which was derived from the mechanism of electrode reactions. Measured electrochemical impedance spectra at various electrode potentials were analyzed by using the complex non-linear least-squares fitting method. The results show that impedance spectra consist of 2 high-to- medium frequency depressed arcs and a low frequency straight line. The high frequency arc is attributed to the absorption reaction of lithium ions into the oxide film, the medium frequency arc is attributed to the charge transfer reaction at the vanadium oxide/electrolyte interface and the low frequency is characterized by a straight line with a phase angle of 45° corresponding to the diffusion of lithium ion through vanadium oxide phase. The experimental and calculated results are compared and discussed focusing on the electrochemical performance and the state of charge of the electrode. Moreover, the high consistence of the fitted values of the model to the experimental data indicates that this mathematical model does give a satisfying description of the intercalation process of vanadium pentoxide xerogel films.
文摘The nanocomposite films were prepared by direct intercalation of poly(ethylene oxide) and PEO into MoO 3 xerogel via sol-gel route.The electrochromic behavior and the chemical conditions of Li + ions were investigated by cyclic voltammograms,UV-visible spectral transmittance and XPS.The results show that the cycling efficiency and the reversibility of insertion/extraction of Li + ions in (PEO) 1MoO 3·nH 2O nanocomposite film were improved.The intercalation of PEO into MoO 3 xerogel modulated the wavelength range of electrochromism and enhanced the electrochromic efficiency.Two different chemical conditions of Li + ions existing in the interlayer and interstitial positions of MoO 3 lattice were observed in MoO 3 xerogel and (PEO) 1MoO 3·nH 2O nanocomposite films.
基金supported by the internal grant of the Faculty of Advanced Technology and Chemistry, MUT(No. GW-08-977)
文摘The catalytically assisted self-propagating high-temperature synthesis of carbon fibrous nanostructures, where the iron-doped colloidal carbon xerogel is proposed as a catalyst system, was examined. The carbon xerogel was prepared through carbonization of an iron doped organic xerogel at temperatures ranging from 600 to 1050℃. The reaction between calcium carbide and hexachloroethane in the presence of sodium azide is exothermic enough to proceed at a high temperature, self-sustaining regime. The combustion reactions of those mixtures enriched with iron-doped carbon xerogels were conducted in a stainless steel reactor---calorimetric bomb under an initial pressure of 1 MPa of argon. Scanning electron microscopy analysis of the combustion products revealed low yield of various type of carbon fibers （presumably nanotubes）, which grew via the tip-growth mechanism. The fibrous nanostructures were found in the vicinity of the spot of ignition, while in the outer and cooler area of the reactor, dusty products with soot-like morphology dominated. No significant correlation between the pyrolysis temperature of the carbon xerogel and the morphology of the obtained carbon fibrous nanostructures was observed.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10904008)Joint Funds of the National Natural Science Foundation of China (Grant No. 11076008)the Young Scientists Foundation of Sichuan Province of China(Grant No. 2010JQ0006)
文摘A new blue photoluminescent material, a mixed tin and manganese oxide xerogel, is prepared via sol-hydrothermalgel process assisted by citric acid. The composition xerogel exhibits strong blue emission at room temperature, with an emission maximum at 434 nm under short （234 nm） or long-wavelength （343 nm） ultraviolet excitation. The photoluminescent excitation spectrum of the mixed tin and manganese oxide xerogel, monitored at an intensity maximum wavelength of 434 nm of the emission, consists of two excitation peaks at 234 nm and 343 am. With heat treatment temperature increasing from 110 ℃ to 200 ℃, the blue emission intensity increases remarkably, whereas it is almost completely quenched after being treated at 300 ℃. The carbon impurities in the mixed tin and manganese oxide xerogel, confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, should be responsible for the bright blue photoluminescence.
基金This project was supported by National Natural Science Foundation of China (Grant No.59802009 ) and Hubei Province Natural Science Foundation(Grant No. 99J053).
文摘The nanocomposite films were prepared by poly(ethylene oxide), PEO, intercalation in V2O5 xero-gel in sol-gel. The synthesis and state of the films are investigated by the XRD, IR, SEM, etc. The results show that V2O5, xerogel is a layered structure which arranges in c-direction. The mterlayer distance of V2O5 xerogel increases remarkably when PEO is intercalated in V2O5 xero-gel interlayer. PEO has strong interaction with V2O5 host. The surface of the films is homogeneous without holes and cracks.
文摘The V 2O 5 sol was fabricated by ultra fast quenching.The vanadium with low valence (V 4+ ) was found in V 2O 5 xerogel films by XPS analysis.The technology of oxygen top blown was applied to analyze the XPS spectrum difference of V 2O 5 xerogel when the powder of V 2O 5 was melting in air or in oxygen atmosphere.The results show that the different melting atmosphere has certain influences on the chemical valence of V 2O 5 xerogel.
基金Project supported by the Sao Paulo Research Foundation(FAPESP)(2018/10492-1,2018/16360-0,2007/08244-5,2007/54829-5,2017/18574-4,2017/10118-0,2014/50945-4)the Conselho Nacional de Desenvolvimento Cientifico e Tecnológico(CNPq)(465571/2014-0,302874/2017-8,427452/2018-0)。
文摘This paper aims to create visible light driven ternary photocatalysts using zinc oxide(ZnO),cerium(IV)oxide(CeO_(2)),and carbon xerogel(CX) as constituent materials.The use of CeO_(2) is based on the creation of direct-Z-scheme heterojunctions with the ZnO and the consequent diminishing of charge recombination,whereas the carbon xerogel inclusion is predicted to minimize bandgap energy,decrease electro n-hole reco mbination,and boost specific surface area.Furthermo re,the choice of the black-wattle tannin as a carbonaceous precursor was targeted at the development of an environmentally friendly and affordable composite.The existence of the hexagonal phase of zinc oxide and cubic structure of the cerium(IV) oxide in the ternary material was confirmed by X-ray diffractometry and X-ray photoelectron spectroscopy,with the latter also suggesting chemical bonding between the ZnO and the CX due to the creation of zinc oxycarbide complexes.The inclusion of the carbon xerogel provokes a significant modification in the morphology of the ternary material,resulting in an increased surface area and smaller particle aggregates.The CX/ZnO-CeO_(2) ternary composite obtains the highest photocatalytic efficiency among all the materials studied,degrading 100% of 4-chlorophenol under simulated sunlight and 68% under visible radiation,after 5 h.The increased photocatalytic activity can be attributed to the formation of direct Z-scheme heterojunctions between the semiconductors,higher visible light response,and higher specific surface area,as evidenced by the results obtained by active radical scavenging,chronoamperometry,diffuse reflectance spectroscopy,and N_(2) adsorption-desorption isotherms.
文摘Mesoporous polyethylene glycol-resorcinol and formaldehyde（PEG-RF） carbon xerogels were prepared by a new polymer blend method in which PEG-RF mixed organic xerogels were synthesized by blending thermally unstable polyethylene glycol with organic monomers, resorcinol and formaldehyde and then subjected to pyrolization at 1 000 ℃. The influences of mass ratio of PEG to the theoretical yield of RF xerogel, m（PEG）/m（RF） and the （relative） molecular mass of PEG on the pore structure and electric double layer capacitance（EDLC） performance of PEG-RF carbon xerogels were investigated. The results show that PEG under different conditions leads to the difference of phase separation structure of the polymer blend and thus the change of pore structure of PEG-RF carbon xerogels. Specific surface area and capacity of PEG-RF carbon xerogels in 30% H2SO4 solution can reach （755 m2/g） and 150 F/g, respectively. Their surface can be fully utilized to form electric double layer. However, the pore structure differences of PEG-RF carbon xerogels result in their different EDLC performances. The distributed capacitance effect increases with decreasing the pore size of PEG-RF carbon xerogels.
文摘Vanadium pentoxide xerogel（VXG） films were prepared by rapid quenching, then corn type 2016 size lithium rechargeable batteries were assembled and tested with the VXG film electrodes and lithium anodes. Electrochemical impedance spectroscopy（EIS） analysis result reveals the expected response for intercalation, except that there is almost no Warburg （diffusion） component. Analyses results of cyclic voltammetry（CV）, constant discharge （CD） and discharge-charge（DC） indicate that the sample achieves a high initial discharge specific capacity of approximate 400 mA·h/g and a corresponding efficiency of 97 % in the voltage diapason of 1.5 - 4.0 V with a draining current of 60 mA/g. Its preservation ratio of capacity still keeps as high as 85 % even after 100 cycles. The good electrochemical performance indicates that VXG film material is a promising cathode for lithium rechargeable batteries.
文摘The extractant tri-n-octylamine （TOA） was encapsulated in calcium alginate （CaALG） xerogel polymer matrices and the selective separation of Au（III） ions in HCI solution was investigated. The features of the TOA microcapsules （TOA-MCs） were examined using DM, SEM/EDS and EPMA. The adsorption and elution properties of Au（III） were studied by the column method using spherical and highly porous TOA-MCs. The uptake properties of precious metals （Au（IIl）, Pt（IV）, and Pd（II）） were examined by the batch method using TOA-MCs in different concentrations of hydrochloric acid （HCI） solution. The order of uptake （%） of the precious metals was Au（III） 〉 Pt（IV） 〉 Pd（II）. TOA-MCs have strong affinity towards Au（III） in HCI solution. The uptake （%） of Au（III） by TOA-MCs was estimated to be -100% and equilibrium was attained within 1 hour. The breakthrough and elution behaviors of Au（III） were examined by varying the Au（III） concentration in the feed, flow rate, reaction temperature, and eluent concentration. The Au（IlI） in 1 M HCI solution was effectively extracted with TOA-MCs in the column operation. The breakthrough curve showed the S-shaped profile and no dislodgement of TOA from the matrices of CaALG. The breakthrough curve rose steeply and the uptake of Au（IIl） was fairly fast, which indicated a relatively high uptake rate of Au（III） in TOA-MCs. The break point （5% breakthrough） and breakthrough capacity （B. T. Capacity） were estimated to be 82 cm3 and 0.60 mmol/g, respectively. The total capacity （T. capacity） was estimated to be 1.30 mmol/g, which was considerably larger than those of conventional resins. The elution properties of Au（Ill） were studied by varying the concentration of thiourea （0.025 M-1 M） in 1 M HC1 solution. The retention volume （VR, cm3） tended to decrease with the increase in thiourea （TU） concentration. The loaded Au（III） ions were successfully eluted （- 100%, total elution percentage） by the eluent of TU （0.5 M） in HC1 （1 M） solution. The alginate gel microcapsules enclosing TOA extractant were thus effective for the selective separation and recovery of Au（IIl） ions in HCI solution.
文摘In the present study, sol-gel process is used to synthesize P-doped TiO2 xerogels by the cogelation method of a functionalized P alkoxide, (NH2-(CH2)2-NH-(CH2)2-P(O)-(OC2H5)2) with Ti(OC3H7)4 in either 2-methoxyethanol or isopropanol. The phosphorus-doping improved the thermal stability of titania and decreased the phase transformation of anatase into rutile. This modification by phosphorus shifted the absorption edge of titania to the visible region as proved by Diffuse reflectance measurements, and thus offers the possibility to produce visible light effective TiO2 photocatalyst. The excellent photocatalytic activity of P-doped TiO2 xerogels compared to pure TiO2 could be explained by its high surface area and small TiO2-anatase crystallite size. From these results, it was proved by using three different models that phosphorus intrinsically influences the photocatalytic activity.
文摘Small angle X-ray scattering (SAXS) with synchrotron radiation as X-ray source has been used to study the structure of silica xerogels prepared by sol-gel process. Both the agreement of SAXS profiles with and the deviation from Porod’s law and Debye’s theory have been found, showing that there are differences between the structures of these xerogels. The specific surfaces of the samples whose SAXS profiles agreed with Porod’s law and Debye’s theory have been determined by analyzing SAXS data according to the methods of Porod and Debye, respectively, and the results of both methods used were found to be similar. We have proposed the corresponding Porod and Debye analysis methods to determine the specific surfaces of samples whose SAXS profiles do not agree with Porod’s law and Debye’s theory, i.e. the negative or positive deviation. The results of both methods used here were also found to be close to each other. The specific surfaces fell between approximately 80-150 m2/cm3 for the samples prepared
