Acetone is a common volatile organic compound that can cause harm to human health when inhaled in small amounts.Therefore,the development of fast response and low detection limit acetone sensors becomes crucial.In thi...Acetone is a common volatile organic compound that can cause harm to human health when inhaled in small amounts.Therefore,the development of fast response and low detection limit acetone sensors becomes crucial.In this study,a core-shell spherical TiO_(2) sensor with a rich pore structure was designed.This sensor exhibited excellent sensing properties,including higher responsiveness(100 ppm acetone,R_(a)/R_(g)=80),lower detection limit(10 ppb)and short response time(8 s).The problem is that the sensing mechanism between TiO_(2) and acetone is not thoroughly analyzed.To gain further insight,the interaction process of TiO_(2) core-shell spheres and acetone under varying oxygen content environments was investigated by dynamic testing,X-ray photoelectron spectroscopy,in-situ Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry.The research results show that acetone not only adsorbs on the surface of the material and reacts with adsorbed oxygen,but also undergoes catalytic oxidation reaction with TiO_(2) core-shell spheres.Significantly,in high oxygen content environments,acetone undergoes oxidation to form intermediates such as acids and anhydrides that are difficult to desorpt on the surface of the material,thus prolonging the recovery time of the sensor.The discovery of this sensing process will provide some guidance for the design of acetone sensing materials in the future.Meanwhile,this also imparts valuable references and insights for the investigation of the mechanism and application of other sensitive metal oxide materials.展开更多
Carbon residue is a waste by-product produced during the rapid pyrolysis of biomass into bio-oil,and the fragile nature and poor pore processability making it difficult to dispose.In this study,carbon residues obtaine...Carbon residue is a waste by-product produced during the rapid pyrolysis of biomass into bio-oil,and the fragile nature and poor pore processability making it difficult to dispose.In this study,carbon residues obtained from various biomasses waste are selfassembled into macroscopic porous carbon spheres(CSs),through interactions with cellulose nanofibrils(CNF)and in situ treatment by KOH to remove their high ash content.The micro-and meso-pore structure of CSs can be influenced by the type of raw biomasses,pyrolysis heating rate and structure-directing agent,through KOH removal of multiscale ashes and morphology controlling of CSs.Compared to fast pyrolyzed woody biomass,the resulting CSs derived from silicon-rich biomass residue shows superior mesopore volume ranging from 0.3 cm^(3)/g to 0.5 cm^(3)/g,owing to the ash self-templates(nonmetallic oxides).The optimized CS from fast pyrolyzed bamboo residue demonstrates the best shape factor(0.78),highest carbon oxide(CO_(2))gravimetric adsorption capacity(1.8 mmol/g),and low regeneration energy(32 kJ/mol).The life cycle assessment shows the carbon reduction potential of fast pyrolysis residue derived CSs was most contributed by the global warming potential of produced fixed carbon and bio-oil,which is−557.85 kg CO_(2) eq/t wastes.This study highlights a cost-effective and sustainable strategy for CO_(2) capture by carbon residue.展开更多
In this work,Dy_(2)O_(3)rods and layered Dy_(2)WO_(6)heterostructure were effectively interconnected by carbon spheres named Dy_(2)O_(3)/Dy_(2)WO_(6)/C-sph nanocomposite with a confined interface and it was fabricated...In this work,Dy_(2)O_(3)rods and layered Dy_(2)WO_(6)heterostructure were effectively interconnected by carbon spheres named Dy_(2)O_(3)/Dy_(2)WO_(6)/C-sph nanocomposite with a confined interface and it was fabricated using a simple solvothermal approach.These ternary nanocomposites were investigated by X-ray diffraction(XRD),UV-visible diffuse-reflectance spectroscopy(UV-DRS),Fourier transform-infrared spectroscopy(FT-IR),Raman,field emission scanning electron microscopy(FESEM)with energy disperse spectroscopy(EDS),high-resolution transmission electron microscopy(HRTEM),and X-ray photoelectron spectroscopy(XPS)analyses systematically.The XRD data expose that the synthesized materials are formed with a virtuous crystalline state.The charge storage properties and electrochemical performances of the as-synthesized nanocomposites and pure components were assessed with the help of cyclic voltammogram(CV),galvanostatic charge-discharge studies(GCD),and electrochemical impedance studies(EIS),respectively.The rare-earth-based novel Dy_(2)O_(3)/Dy_(2)WO_(6)/C-sph nanocomposite as wo rking electrodes established commendable electrochemical perfo rmances with a maximum specific capacitance value of 123 F/g at a current density of 0.4 A/g in 2.0 mol/L aqueous KOH solution.According to the stability measurements,it was observed that the initial capacitance was maintained at~93%even after 2500 cycles,indicating that good electrochemical stability with the lowest internal resistance values was obtained from EIS analysis.The electrochemical measurements suggest that the Dy_(2)O_(3)/Dy_(2)WO_(6)/C-sph nanocomposite enables great competence and can be used as alternative electrode material in supercapacitor devices to avail high energy efficiency in a sustainable approach.展开更多
Exploring efficient and nonprecious metal electrocatalysts of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is crucial for developing rechargeable zinc-air batteries(ZABs).Herein,an alloying-degree c...Exploring efficient and nonprecious metal electrocatalysts of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is crucial for developing rechargeable zinc-air batteries(ZABs).Herein,an alloying-degree control strategy was employed to fabricate nitrogen-doped carbon sphere(NCS)decorated with dual-phase Co/Co_(7)Fe_(3)heterojunctions(CoFe@NCS).The phase composition of materials has been adjusted by controlling the alloying degree.The optimal CoFe_(0.08)@NCS electrocatalyst displays a half-wave potential of 0.80 V for ORR and an overpotential of 283 mV at 10 mA·cm^(-2)for OER in an alkaline electrolyte.The intriguing bifunctional electrocatalytic activity and durability is attributed to the hierarchically porous structure and interfacial electron coupling of highly-active Co_(7)Fe_(3)alloy and metallic Co species.When the CoFe_(0.08)@NCS material is used as air-cathode catalyst of rechargeable liquid-state zinc-air battery(ZAB),the device shows a high peak power-density(157 mW·cm^(-2))and maintains a stable voltage gap over 150 h,outperforming those of the benchmark(Pt/C+RuO_(2))-based device.In particular,the as-fabricated solid-state flexible ZAB delivers a reliable compatibility under different bending conditions.Our work provides a promising strategy to develop metal/alloy-based electrocatalysts for the application in renewable energy conversion technologies.展开更多
Monoclinic BiVO4 hollow nanospheres were successfully prepared via template-free method using citric acid （C6H8O7） as chelating agent and characterized by X-ray diffraction patterns, transmission electron microscope...Monoclinic BiVO4 hollow nanospheres were successfully prepared via template-free method using citric acid （C6H8O7） as chelating agent and characterized by X-ray diffraction patterns, transmission electron microscope, UV-Vis DRS, and TG-DTA technique. C6H8O7 played an important role in the formation of hollow spheres. Morphology observations revealed that when appropriate amount of C6H8O7 was introduced, the cavity with the diameter of 40 nm was obtained in BiVO4 nanospheres. UV-Vis diffuse reflectance spectra indicated that the samples had absorption in both UV and visible light region. The photocatalytic activities were evaluated by the degradation of methylene blue under Xe lamp irradiation. Hollow spheres endow BiVO4 samples with greatly improved photocatalytic activity. A possible formation mechanism of hollow spheres was proposed.展开更多
Development of efficient and stable metal catalysts for the selective aqueous phase hydrodeoxygenation(HDO)of biomass-derived oxygenates to value-added biofuels is highly desired.An innovative surface microenvironment...Development of efficient and stable metal catalysts for the selective aqueous phase hydrodeoxygenation(HDO)of biomass-derived oxygenates to value-added biofuels is highly desired.An innovative surface microenvironment modulation strategy was used to construct the nitrogen-doped hollow carbon sphere encapsulated with Pd(Pd@NHCS-X,X:600–800)nanoreactors for catalytic HDO of biomass-derived vanillin in water.The specific surface microenvironments of Pd@NHCS catalysts including the electronic property of active Pd centers and the surface wettability and porous structure of NHCS supports could be well-controlled by the calcination temperature of catalysts.Intrinsic kinetic evaluations demonstrated that the Pd@NHCS-600 catalyst presented a high turnover frequency of 337.77 h^(–1)and a low apparent activation energy of 18.63 kJ/mol.The excellent catalytic HDO performance was attributed to the unique surface microenvironment of Pd@NHCS catalyst based on structure-performance relationship analysis and DFT calculations.It revealed that pyridinic N species dominated the electronic property regulation of Pd sites through electronic metal-support interaction(EMSI)and produced numerous electron-rich active Pd centers,which not only intensified the dissociation and activation of H2 molecules,but also substantially improved the activation capability of vanillin via the enhanced adsorption of–C=O group.The fine hydrophilicity and abundant porous structure promoted the uniform dispersion of catalyst and ensured the effective access of reactants to catalytic active centers in water.Additionally,the Pd@NHCS-600 catalyst exhibited excellent catalytic stability and broad substrate applicability for the selective aqueous phase HDO of various biomass-derived carbonyl compounds.The proposed surface microenvironment modulation strategy will provide a new consideration for the rational design of high-performance nitrogen-doped carbon-supported metal catalysts for catalytic biomass transformation.展开更多
Ceramic hollow spheres have great potential for deep-sea applications.However,the irregularity of the conventional molding process,among other reasons,results in low wall thickness uniformity of hollow spheres.To solv...Ceramic hollow spheres have great potential for deep-sea applications.However,the irregularity of the conventional molding process,among other reasons,results in low wall thickness uniformity of hollow spheres.To solve this problem,in this work,we developed a biaxial rotation grouting process for deep-sea ceramic hollow buoyancy spheres,which improves the drawbacks of the traditional rotary grouting method that results in poor wall thickness uniformity of the hollow spheres due to its irregular rotational processing.In this paper,an experimental study was carried out to investigate the effects of different rotational methods,rotational speeds,rotational time,solid phase content,etc.on the wall thickness uniformity of ceramic hollow spheres.The results show that the hollow floating balls prepared by the biaxial rotation method have the lowest wall thickness standard deviation(0.04)when the rotation speed is 60 rpm,the molding time is 8 min,and the solid phase content is 70 wt%.After the hydrostatic pressure test of 120 MPa,the hydrostatic compressive strength of hollow spheres prepared by the biaxial rotation method was increased by 31.67%compared with that of the traditional process.展开更多
This study presents a novel Li metal host material with a unique hollow nano-spherical structure that incorporates Ag nano-seeds into a graphitic carbon nitride(g-C_(3)N_(4))shell layer,referred to as g-C_(3)N_(4)@Ag ...This study presents a novel Li metal host material with a unique hollow nano-spherical structure that incorporates Ag nano-seeds into a graphitic carbon nitride(g-C_(3)N_(4))shell layer,referred to as g-C_(3)N_(4)@Ag hollow spheres.The g-C_(3)N_(4)@Ag spheres provide a managed internal site for Li metal encapsulation and promote stable Li plating.The g-C_(3)N_(4) spheres are uniformly coated using polydopamine,which has an adhesive nature,to enhance lithium plating/stripping stability.The strategic presence of Ag nano-seeds eliminates the nucleation barrier,properly directing Li growth within the hollow spheres.This design facilitates highly reversible and consistent lithium deposition,offering a promising direction for the production of high-performance lithium metal anodes.These well-designed g-C_(3)N_(4)@Ag hollow spheres ensure stable Li plating/stripping kinetics over more than 500 cycles with a high coulombic efficiency of over 97%.Furthermore,a full cell made using LiNi_(0.90)Co_(0.07)Mn_(0.03)O_(2) and Li-g-C_(3)N_(4)@Ag host electrodes demonstrated highly competitive performance over 200 cycles,providing a guide for the implementation of this technology in advanced lithium metal batteries.展开更多
Spherical objects are widely used in target localization applications,and the existing sphere localization methods with cameras or total stations both have some limitations.A new high-precision sphere localization met...Spherical objects are widely used in target localization applications,and the existing sphere localization methods with cameras or total stations both have some limitations.A new high-precision sphere localization method with a theodolite is proposed in this paper.From the view point of the theodolite,the contour points of a sphere with a known radius are measured as latitude-longitude coordinates.It is observed that the center of the target sphere is located on a cylindrical surface constructed with the latitude-longitude coordinates,and therefore the latitude-longitude coordinates of at least three contour points can be used to construct a set of ternary quadratic equations.The Gröbner basis method is used to compute at most four real solutions of the sphere center coordinates.To distinguish the only meaningful solution from the other possible real solutions,a pre-processing of the measured longitude values is also proposed.The factors affecting the positioning accuracy of the sphere center are evaluated in simulation experiments,which are used to obtain an empirical estimation model of the positioning error.Real data experiments are also performed and the results show that the proposed method can achieve high localization precision.展开更多
It is rather essential to design glorious system with high CO_(2) adsorption capacity and electron migration efficiency for improving selective and effective CO_(2) reduction into solar fuels.Here,as-synthesized pheno...It is rather essential to design glorious system with high CO_(2) adsorption capacity and electron migration efficiency for improving selective and effective CO_(2) reduction into solar fuels.Here,as-synthesized phenolic resin spheres via suspension polymerization were carbonized and activated by water vapor to obtain activated carbon spheres(ACSs).Subsequently,Bi_(2)MoO_(6)/ACSs were prepared via hydrothermal-impregnated method.The systematical characterizations of samples,including XRD,XPS,SEM,EDX,DRS,BET,PL,CO_(2) adsorption isotherm,EIS and transient photocurrent,were analyzed.The results clearly demonstrated that Bi_(2)MoO_(6) with suitable oxidation reduction potentials and bandgap and ACSs with admirable CO_(2) adsorption and electrical conductivity not only enhanced separation efficiency of photoindued electron-hole pair,but also displayed as 1.8 times CO_(2) reduction activity to CO as single Bi_(2)MoO_(6) sample under Xe-lamp irradiation.Finally,a concerned photocatalytic CO_(2) reduction mechanism was proposed and investigated.Our findings should provide innovative guidance for designing a series of photocatalytic CO_(2) reduction materials with highly efficient and selective ability.展开更多
Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis d...Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis diffusion reflectance spectroscopy.The results indicate that all the prepared samples have the same hexagonal wurtzite phase and exhibit good size uniformity and regularity.Degradation of rhodamine-B（RhB） was used to evaluate the photocatalytic activities of ZnxCd1-xS samples.Zn0.4Cd0.6S possessed the best photocatalytic activity and exhibited high stability during the reaction.展开更多
Different-sized hollow SiO2 spheres of 249–1348 nm in diameter were successfully prepared by using Na2SiO3 as the precursor and using polystyrene and polystyrene-methyl acrylic acid latexes as the templates. The diam...Different-sized hollow SiO2 spheres of 249–1348 nm in diameter were successfully prepared by using Na2SiO3 as the precursor and using polystyrene and polystyrene-methyl acrylic acid latexes as the templates. The diameter and shell thickness of the hollow SiO2 spheres increase with increasing the latex template diameter at a given mass ratio of SiO2 to latex template. The diameter and shell thickness of the hollow SiO2 spheres also increase with increasing the mass ratios of SiO2 to latex template. The presence of carboxylic acid groups on the surfaces of polystyrene-methyl acrylic acid latex templates favors the formation of dense and uniform SiO2 shells. The hollow SiO2 sphere is constructed by mesoporous shell with large specific surface area. When glyphosate is used as a release model chemical, glyphosate release rate is tuned by varying the shell thickness.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))has emerged as a remarkably promising photocatalyst for addressing environmental and energy issues;however,it exhibits only moderate photocatalytic activity because of its low spe...Graphitic carbon nitride(g-C_(3)N_(4))has emerged as a remarkably promising photocatalyst for addressing environmental and energy issues;however,it exhibits only moderate photocatalytic activity because of its low specific surface area and high recombination of carriers.Preparation of crystalline g-C_(3)N_(4) by the molten salt method has proven to be an effective method to improve the photocatalytic activity.However,crystalline g-C_(3)N_(4) prepared by the conventional molten salt method exhibits a less regular morphology.Herein,highly crystalline g-C_(3)N_(4) hollow spheres(CCNHS)were successfully prepared by the molten salt method using cyanuric acid-melamine as a precursor.The higher crystallization of the CCNHS samples not only repaired the structural defects at the surface of the CCNHS samples but also established a built-in electric field between heptazine-based g-C_(3)N_(4) and triazine-based g-C_(3)N_(4).The hollow structure improved the level of light energy utilization and increased the number of active sites for photocatalytic reactions.Because of the above characteristics,the as-prepared CCNHS samples simultaneously realized photocatalytic hydrogen evolution with the degradation of the plasticizer bisphenol A.This research offers a new perspective on the structural optimization of supramolecular self-assembly.展开更多
Micrometer-sized MoO2 hollow spheres were synthesized hydrothermally with ammonium heptamolybdate tetrahydrate as molybdenum source, Cetyltrimethylammonium bromide as structure-directing agent and C2H5OH as reducing a...Micrometer-sized MoO2 hollow spheres were synthesized hydrothermally with ammonium heptamolybdate tetrahydrate as molybdenum source, Cetyltrimethylammonium bromide as structure-directing agent and C2H5OH as reducing agent, respectively. The products were investigated by X-ray diffraction, thermo gravimetry and differential thermal analysis, scanning electron microscopy, transmission electron micraseopy and X-ray photoelectron spectroscopy. A morphology transition of ＂blocks-solid spheres-hollow spheres＂ during the growth procfess was observed and the possible mechanism for the formation of MoO2 samples was proposed to be through a microscale Kirkendall effcct.展开更多
When a shock wave interacts with a group of solid spheres,non-linear aerodynamic behaviors come into effect.The complicated wave reflections such as the Mach reflection occur in the wave propagation process.The wave i...When a shock wave interacts with a group of solid spheres,non-linear aerodynamic behaviors come into effect.The complicated wave reflections such as the Mach reflection occur in the wave propagation process.The wave interactions with vortices behind each sphere's wake cause fluctuation in the pressure profiles of shock waves.This paper reports an experimental study for the aerodynamic processes involved in the interaction between shock waves and solid spheres.A schlieren photography was applied to visualize the various shock waves passing through solid spheres.Pressure measurements were performed along different downstream positions.The experiments were conducted in both rectangular and circular shock tubes.The data with respect to the effect of the sphere array, size,interval distance,incident Mach number,etc.,on the shock wave attenuation were obtained.展开更多
Recently, researchers have focused on designing and fabricating highly efficient catalysts for photocatalytic organic pollutant removal. Herein, CeO_(2) hollow spheres were prepared through a simple template method fo...Recently, researchers have focused on designing and fabricating highly efficient catalysts for photocatalytic organic pollutant removal. Herein, CeO_(2) hollow spheres were prepared through a simple template method followed by calcination at different temperatures for the tetracycline(TC) degradation under simulated solar light illumination. With a calcination temperature ranging from400 to 800 ℃, the as-prepared CeO_(2) hollow structure annealed at 600 ℃(C_(600)) exhibited the best degradation performance with a degradation rate constant of0.066 min-1, which was about six and five times higher than those of the uncalcined sample(C_(0)) and the sample calcined at 800 ℃(C_(800)), respectively. Moreover, sample C_(600)was also superior to the CeO_(2) solid particle photocatalyst. The characterisation results showed that the improved photocatalytic performance was mainly ascribed to the synergistic effect of large specific surface areas, high crystallisation and excellent light scattering ability. Furthermore, the results of active species trapping experiments demonstrated that the superoxide anion(·O_(2)^(-)) radical and hole(h^(+)) played dominant roles in TC degradation. Subsequently, the possible TC degradation pathways and photocatalytic mechanism of CeO_(2) hollow spheres were proposed on the basis of high-performance liquid chromatography–mass spectrometry analysis, main active species and band edge positions of CeO_(2). The results of this study provide a basis for designing and exploring hollow structure catalysts for energy conversion and environmental remediation.展开更多
CeO_2 hollow spheres were synthesized by polystryrene sphere（PS） templates and CeO_2 nanoparticles were prepared by a facile method. The as-obtained products were characterized by scanning electron microscopy（SEM）...CeO_2 hollow spheres were synthesized by polystryrene sphere（PS） templates and CeO_2 nanoparticles were prepared by a facile method. The as-obtained products were characterized by scanning electron microscopy（SEM）, N_2 adsorption-desorption, X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR） and UV-vis diffuse reflectance spectra. The results showed that the structure of the obtained CeO_2 hollow spheres was hollow microsphere with a diameter of 380 nm and the average particle size of CeO_2 nanoparticles was about 1700 nm. The two samples＇ Brunauer-Emmett-Teller（BET） surface area was 67.1 and 37.2 m^2/g. The CeO_2 hollow spheres had a better performance than nanoparticles at UV-shielding because of higher surface area and the structure of hollow sphere.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21771060 and 61271126)the International Science&Technology Cooperation Program of China(No.2016YFE0115100)+2 种基金Heilongjiang Provincial Natural Science Foundation of China(No.LH_(2)023B021)Reform and Development Fund Project of Local University supported by the Central Government,Heilongjiang Touyan Innovation Team Program,New Era Excellent Master’s and Doctoral Dissertations of Heilongjiang Province(No.LJYXL2023-020)Basic Scientific Research Project for Heilongjiang Provincial Colleges and Universities(No.2023-KYYWF-1482).
文摘Acetone is a common volatile organic compound that can cause harm to human health when inhaled in small amounts.Therefore,the development of fast response and low detection limit acetone sensors becomes crucial.In this study,a core-shell spherical TiO_(2) sensor with a rich pore structure was designed.This sensor exhibited excellent sensing properties,including higher responsiveness(100 ppm acetone,R_(a)/R_(g)=80),lower detection limit(10 ppb)and short response time(8 s).The problem is that the sensing mechanism between TiO_(2) and acetone is not thoroughly analyzed.To gain further insight,the interaction process of TiO_(2) core-shell spheres and acetone under varying oxygen content environments was investigated by dynamic testing,X-ray photoelectron spectroscopy,in-situ Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry.The research results show that acetone not only adsorbs on the surface of the material and reacts with adsorbed oxygen,but also undergoes catalytic oxidation reaction with TiO_(2) core-shell spheres.Significantly,in high oxygen content environments,acetone undergoes oxidation to form intermediates such as acids and anhydrides that are difficult to desorpt on the surface of the material,thus prolonging the recovery time of the sensor.The discovery of this sensing process will provide some guidance for the design of acetone sensing materials in the future.Meanwhile,this also imparts valuable references and insights for the investigation of the mechanism and application of other sensitive metal oxide materials.
基金supported by the National Natural Science Foundation of China(Youth Fund,52200168).
文摘Carbon residue is a waste by-product produced during the rapid pyrolysis of biomass into bio-oil,and the fragile nature and poor pore processability making it difficult to dispose.In this study,carbon residues obtained from various biomasses waste are selfassembled into macroscopic porous carbon spheres(CSs),through interactions with cellulose nanofibrils(CNF)and in situ treatment by KOH to remove their high ash content.The micro-and meso-pore structure of CSs can be influenced by the type of raw biomasses,pyrolysis heating rate and structure-directing agent,through KOH removal of multiscale ashes and morphology controlling of CSs.Compared to fast pyrolyzed woody biomass,the resulting CSs derived from silicon-rich biomass residue shows superior mesopore volume ranging from 0.3 cm^(3)/g to 0.5 cm^(3)/g,owing to the ash self-templates(nonmetallic oxides).The optimized CS from fast pyrolyzed bamboo residue demonstrates the best shape factor(0.78),highest carbon oxide(CO_(2))gravimetric adsorption capacity(1.8 mmol/g),and low regeneration energy(32 kJ/mol).The life cycle assessment shows the carbon reduction potential of fast pyrolysis residue derived CSs was most contributed by the global warming potential of produced fixed carbon and bio-oil,which is−557.85 kg CO_(2) eq/t wastes.This study highlights a cost-effective and sustainable strategy for CO_(2) capture by carbon residue.
基金supported by Selective Excellence Research Initiative-2023,SRM Institute of Science and Technology(SRMIST/R/AR(A)/SERI2023/174/26-3944)。
文摘In this work,Dy_(2)O_(3)rods and layered Dy_(2)WO_(6)heterostructure were effectively interconnected by carbon spheres named Dy_(2)O_(3)/Dy_(2)WO_(6)/C-sph nanocomposite with a confined interface and it was fabricated using a simple solvothermal approach.These ternary nanocomposites were investigated by X-ray diffraction(XRD),UV-visible diffuse-reflectance spectroscopy(UV-DRS),Fourier transform-infrared spectroscopy(FT-IR),Raman,field emission scanning electron microscopy(FESEM)with energy disperse spectroscopy(EDS),high-resolution transmission electron microscopy(HRTEM),and X-ray photoelectron spectroscopy(XPS)analyses systematically.The XRD data expose that the synthesized materials are formed with a virtuous crystalline state.The charge storage properties and electrochemical performances of the as-synthesized nanocomposites and pure components were assessed with the help of cyclic voltammogram(CV),galvanostatic charge-discharge studies(GCD),and electrochemical impedance studies(EIS),respectively.The rare-earth-based novel Dy_(2)O_(3)/Dy_(2)WO_(6)/C-sph nanocomposite as wo rking electrodes established commendable electrochemical perfo rmances with a maximum specific capacitance value of 123 F/g at a current density of 0.4 A/g in 2.0 mol/L aqueous KOH solution.According to the stability measurements,it was observed that the initial capacitance was maintained at~93%even after 2500 cycles,indicating that good electrochemical stability with the lowest internal resistance values was obtained from EIS analysis.The electrochemical measurements suggest that the Dy_(2)O_(3)/Dy_(2)WO_(6)/C-sph nanocomposite enables great competence and can be used as alternative electrode material in supercapacitor devices to avail high energy efficiency in a sustainable approach.
基金financially supported by the National Natural Science Foundation of China(No.22279047)the Instrumental Analysis Center of Jiangsu University of Science and Technology。
文摘Exploring efficient and nonprecious metal electrocatalysts of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)is crucial for developing rechargeable zinc-air batteries(ZABs).Herein,an alloying-degree control strategy was employed to fabricate nitrogen-doped carbon sphere(NCS)decorated with dual-phase Co/Co_(7)Fe_(3)heterojunctions(CoFe@NCS).The phase composition of materials has been adjusted by controlling the alloying degree.The optimal CoFe_(0.08)@NCS electrocatalyst displays a half-wave potential of 0.80 V for ORR and an overpotential of 283 mV at 10 mA·cm^(-2)for OER in an alkaline electrolyte.The intriguing bifunctional electrocatalytic activity and durability is attributed to the hierarchically porous structure and interfacial electron coupling of highly-active Co_(7)Fe_(3)alloy and metallic Co species.When the CoFe_(0.08)@NCS material is used as air-cathode catalyst of rechargeable liquid-state zinc-air battery(ZAB),the device shows a high peak power-density(157 mW·cm^(-2))and maintains a stable voltage gap over 150 h,outperforming those of the benchmark(Pt/C+RuO_(2))-based device.In particular,the as-fabricated solid-state flexible ZAB delivers a reliable compatibility under different bending conditions.Our work provides a promising strategy to develop metal/alloy-based electrocatalysts for the application in renewable energy conversion technologies.
文摘Monoclinic BiVO4 hollow nanospheres were successfully prepared via template-free method using citric acid （C6H8O7） as chelating agent and characterized by X-ray diffraction patterns, transmission electron microscope, UV-Vis DRS, and TG-DTA technique. C6H8O7 played an important role in the formation of hollow spheres. Morphology observations revealed that when appropriate amount of C6H8O7 was introduced, the cavity with the diameter of 40 nm was obtained in BiVO4 nanospheres. UV-Vis diffuse reflectance spectra indicated that the samples had absorption in both UV and visible light region. The photocatalytic activities were evaluated by the degradation of methylene blue under Xe lamp irradiation. Hollow spheres endow BiVO4 samples with greatly improved photocatalytic activity. A possible formation mechanism of hollow spheres was proposed.
文摘Development of efficient and stable metal catalysts for the selective aqueous phase hydrodeoxygenation(HDO)of biomass-derived oxygenates to value-added biofuels is highly desired.An innovative surface microenvironment modulation strategy was used to construct the nitrogen-doped hollow carbon sphere encapsulated with Pd(Pd@NHCS-X,X:600–800)nanoreactors for catalytic HDO of biomass-derived vanillin in water.The specific surface microenvironments of Pd@NHCS catalysts including the electronic property of active Pd centers and the surface wettability and porous structure of NHCS supports could be well-controlled by the calcination temperature of catalysts.Intrinsic kinetic evaluations demonstrated that the Pd@NHCS-600 catalyst presented a high turnover frequency of 337.77 h^(–1)and a low apparent activation energy of 18.63 kJ/mol.The excellent catalytic HDO performance was attributed to the unique surface microenvironment of Pd@NHCS catalyst based on structure-performance relationship analysis and DFT calculations.It revealed that pyridinic N species dominated the electronic property regulation of Pd sites through electronic metal-support interaction(EMSI)and produced numerous electron-rich active Pd centers,which not only intensified the dissociation and activation of H2 molecules,but also substantially improved the activation capability of vanillin via the enhanced adsorption of–C=O group.The fine hydrophilicity and abundant porous structure promoted the uniform dispersion of catalyst and ensured the effective access of reactants to catalytic active centers in water.Additionally,the Pd@NHCS-600 catalyst exhibited excellent catalytic stability and broad substrate applicability for the selective aqueous phase HDO of various biomass-derived carbonyl compounds.The proposed surface microenvironment modulation strategy will provide a new consideration for the rational design of high-performance nitrogen-doped carbon-supported metal catalysts for catalytic biomass transformation.
基金Funded by the Key Research and Development Program of Shandong Province(No.2020JMRH0101)。
文摘Ceramic hollow spheres have great potential for deep-sea applications.However,the irregularity of the conventional molding process,among other reasons,results in low wall thickness uniformity of hollow spheres.To solve this problem,in this work,we developed a biaxial rotation grouting process for deep-sea ceramic hollow buoyancy spheres,which improves the drawbacks of the traditional rotary grouting method that results in poor wall thickness uniformity of the hollow spheres due to its irregular rotational processing.In this paper,an experimental study was carried out to investigate the effects of different rotational methods,rotational speeds,rotational time,solid phase content,etc.on the wall thickness uniformity of ceramic hollow spheres.The results show that the hollow floating balls prepared by the biaxial rotation method have the lowest wall thickness standard deviation(0.04)when the rotation speed is 60 rpm,the molding time is 8 min,and the solid phase content is 70 wt%.After the hydrostatic pressure test of 120 MPa,the hydrostatic compressive strength of hollow spheres prepared by the biaxial rotation method was increased by 31.67%compared with that of the traditional process.
基金supported by the National Research Council of Science&Technology(NST)grant by the Korea government(MSIT)(No.GTL24011-000)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.RS-2023-00272863)supported by Korea Institute for Advancement of Technology(KIAT)grant funded by the Korea Government(MOTIE)(P0012748,HRD Program for Industrial Innovation)。
文摘This study presents a novel Li metal host material with a unique hollow nano-spherical structure that incorporates Ag nano-seeds into a graphitic carbon nitride(g-C_(3)N_(4))shell layer,referred to as g-C_(3)N_(4)@Ag hollow spheres.The g-C_(3)N_(4)@Ag spheres provide a managed internal site for Li metal encapsulation and promote stable Li plating.The g-C_(3)N_(4) spheres are uniformly coated using polydopamine,which has an adhesive nature,to enhance lithium plating/stripping stability.The strategic presence of Ag nano-seeds eliminates the nucleation barrier,properly directing Li growth within the hollow spheres.This design facilitates highly reversible and consistent lithium deposition,offering a promising direction for the production of high-performance lithium metal anodes.These well-designed g-C_(3)N_(4)@Ag hollow spheres ensure stable Li plating/stripping kinetics over more than 500 cycles with a high coulombic efficiency of over 97%.Furthermore,a full cell made using LiNi_(0.90)Co_(0.07)Mn_(0.03)O_(2) and Li-g-C_(3)N_(4)@Ag host electrodes demonstrated highly competitive performance over 200 cycles,providing a guide for the implementation of this technology in advanced lithium metal batteries.
基金supported in part by the National Natural Science Foundation of China under Grants 61703373,61873246,U1504604in part by the Key research project of Henan Province Universities under Grant 19A413014.
文摘Spherical objects are widely used in target localization applications,and the existing sphere localization methods with cameras or total stations both have some limitations.A new high-precision sphere localization method with a theodolite is proposed in this paper.From the view point of the theodolite,the contour points of a sphere with a known radius are measured as latitude-longitude coordinates.It is observed that the center of the target sphere is located on a cylindrical surface constructed with the latitude-longitude coordinates,and therefore the latitude-longitude coordinates of at least three contour points can be used to construct a set of ternary quadratic equations.The Gröbner basis method is used to compute at most four real solutions of the sphere center coordinates.To distinguish the only meaningful solution from the other possible real solutions,a pre-processing of the measured longitude values is also proposed.The factors affecting the positioning accuracy of the sphere center are evaluated in simulation experiments,which are used to obtain an empirical estimation model of the positioning error.Real data experiments are also performed and the results show that the proposed method can achieve high localization precision.
基金The authors are thankful to the National Natural Science Foundation of China(No.21978196,21676178,21706179)Shanxi Province Science Foundation for Youths(201801D211008).
文摘It is rather essential to design glorious system with high CO_(2) adsorption capacity and electron migration efficiency for improving selective and effective CO_(2) reduction into solar fuels.Here,as-synthesized phenolic resin spheres via suspension polymerization were carbonized and activated by water vapor to obtain activated carbon spheres(ACSs).Subsequently,Bi_(2)MoO_(6)/ACSs were prepared via hydrothermal-impregnated method.The systematical characterizations of samples,including XRD,XPS,SEM,EDX,DRS,BET,PL,CO_(2) adsorption isotherm,EIS and transient photocurrent,were analyzed.The results clearly demonstrated that Bi_(2)MoO_(6) with suitable oxidation reduction potentials and bandgap and ACSs with admirable CO_(2) adsorption and electrical conductivity not only enhanced separation efficiency of photoindued electron-hole pair,but also displayed as 1.8 times CO_(2) reduction activity to CO as single Bi_(2)MoO_(6) sample under Xe-lamp irradiation.Finally,a concerned photocatalytic CO_(2) reduction mechanism was proposed and investigated.Our findings should provide innovative guidance for designing a series of photocatalytic CO_(2) reduction materials with highly efficient and selective ability.
基金Project (20776016) supported by the National Natural Science Foundation of ChinaProject (20876109) supported by Program for New Century Excellent Talents in University of China
文摘Monodisperse ZnxCd1-xS spheres were successfully fabricated with a high yield by a facile hydrothermal route.The as-prepared samples were characterized by X-ray diffractometry,scanning electron microscopy and UV-vis diffusion reflectance spectroscopy.The results indicate that all the prepared samples have the same hexagonal wurtzite phase and exhibit good size uniformity and regularity.Degradation of rhodamine-B（RhB） was used to evaluate the photocatalytic activities of ZnxCd1-xS samples.Zn0.4Cd0.6S possessed the best photocatalytic activity and exhibited high stability during the reaction.
基金Projects (11KJB530002, CX10B-259Z) supported by Research Funds from Jiangsu Provincial Department of Education, ChinaProject (10zxfk35) supported by Sichuan Province Nonmetallic Composites and Functional Materials Key Laboratory Project, China
文摘Different-sized hollow SiO2 spheres of 249–1348 nm in diameter were successfully prepared by using Na2SiO3 as the precursor and using polystyrene and polystyrene-methyl acrylic acid latexes as the templates. The diameter and shell thickness of the hollow SiO2 spheres increase with increasing the latex template diameter at a given mass ratio of SiO2 to latex template. The diameter and shell thickness of the hollow SiO2 spheres also increase with increasing the mass ratios of SiO2 to latex template. The presence of carboxylic acid groups on the surfaces of polystyrene-methyl acrylic acid latex templates favors the formation of dense and uniform SiO2 shells. The hollow SiO2 sphere is constructed by mesoporous shell with large specific surface area. When glyphosate is used as a release model chemical, glyphosate release rate is tuned by varying the shell thickness.
文摘Graphitic carbon nitride(g-C_(3)N_(4))has emerged as a remarkably promising photocatalyst for addressing environmental and energy issues;however,it exhibits only moderate photocatalytic activity because of its low specific surface area and high recombination of carriers.Preparation of crystalline g-C_(3)N_(4) by the molten salt method has proven to be an effective method to improve the photocatalytic activity.However,crystalline g-C_(3)N_(4) prepared by the conventional molten salt method exhibits a less regular morphology.Herein,highly crystalline g-C_(3)N_(4) hollow spheres(CCNHS)were successfully prepared by the molten salt method using cyanuric acid-melamine as a precursor.The higher crystallization of the CCNHS samples not only repaired the structural defects at the surface of the CCNHS samples but also established a built-in electric field between heptazine-based g-C_(3)N_(4) and triazine-based g-C_(3)N_(4).The hollow structure improved the level of light energy utilization and increased the number of active sites for photocatalytic reactions.Because of the above characteristics,the as-prepared CCNHS samples simultaneously realized photocatalytic hydrogen evolution with the degradation of the plasticizer bisphenol A.This research offers a new perspective on the structural optimization of supramolecular self-assembly.
文摘Micrometer-sized MoO2 hollow spheres were synthesized hydrothermally with ammonium heptamolybdate tetrahydrate as molybdenum source, Cetyltrimethylammonium bromide as structure-directing agent and C2H5OH as reducing agent, respectively. The products were investigated by X-ray diffraction, thermo gravimetry and differential thermal analysis, scanning electron microscopy, transmission electron micraseopy and X-ray photoelectron spectroscopy. A morphology transition of ＂blocks-solid spheres-hollow spheres＂ during the growth procfess was observed and the possible mechanism for the formation of MoO2 samples was proposed to be through a microscale Kirkendall effcct.
基金The project supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China,and the "BaiRen" Plan of Chinese Academy of Sciences
文摘When a shock wave interacts with a group of solid spheres,non-linear aerodynamic behaviors come into effect.The complicated wave reflections such as the Mach reflection occur in the wave propagation process.The wave interactions with vortices behind each sphere's wake cause fluctuation in the pressure profiles of shock waves.This paper reports an experimental study for the aerodynamic processes involved in the interaction between shock waves and solid spheres.A schlieren photography was applied to visualize the various shock waves passing through solid spheres.Pressure measurements were performed along different downstream positions.The experiments were conducted in both rectangular and circular shock tubes.The data with respect to the effect of the sphere array, size,interval distance,incident Mach number,etc.,on the shock wave attenuation were obtained.
基金financially supported by the National Natural Science Foundation of China(Nos.51961135303,51932007,21871217,U1905215 and U1705251)the Innovative Research Funds of Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory(No.XHD2020-001)+2 种基金the National Postdoctoral Program for Innovative Talents(No.BX20200261)China Postdoctoral Science Foundation(No.2020M682501)Dean Research Fund(Nos.04530 and 04554)。
文摘Recently, researchers have focused on designing and fabricating highly efficient catalysts for photocatalytic organic pollutant removal. Herein, CeO_(2) hollow spheres were prepared through a simple template method followed by calcination at different temperatures for the tetracycline(TC) degradation under simulated solar light illumination. With a calcination temperature ranging from400 to 800 ℃, the as-prepared CeO_(2) hollow structure annealed at 600 ℃(C_(600)) exhibited the best degradation performance with a degradation rate constant of0.066 min-1, which was about six and five times higher than those of the uncalcined sample(C_(0)) and the sample calcined at 800 ℃(C_(800)), respectively. Moreover, sample C_(600)was also superior to the CeO_(2) solid particle photocatalyst. The characterisation results showed that the improved photocatalytic performance was mainly ascribed to the synergistic effect of large specific surface areas, high crystallisation and excellent light scattering ability. Furthermore, the results of active species trapping experiments demonstrated that the superoxide anion(·O_(2)^(-)) radical and hole(h^(+)) played dominant roles in TC degradation. Subsequently, the possible TC degradation pathways and photocatalytic mechanism of CeO_(2) hollow spheres were proposed on the basis of high-performance liquid chromatography–mass spectrometry analysis, main active species and band edge positions of CeO_(2). The results of this study provide a basis for designing and exploring hollow structure catalysts for energy conversion and environmental remediation.
基金supported by the Capacity Building Program of Shanghai Local Universities(12160503600)
文摘CeO_2 hollow spheres were synthesized by polystryrene sphere（PS） templates and CeO_2 nanoparticles were prepared by a facile method. The as-obtained products were characterized by scanning electron microscopy（SEM）, N_2 adsorption-desorption, X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FTIR） and UV-vis diffuse reflectance spectra. The results showed that the structure of the obtained CeO_2 hollow spheres was hollow microsphere with a diameter of 380 nm and the average particle size of CeO_2 nanoparticles was about 1700 nm. The two samples＇ Brunauer-Emmett-Teller（BET） surface area was 67.1 and 37.2 m^2/g. The CeO_2 hollow spheres had a better performance than nanoparticles at UV-shielding because of higher surface area and the structure of hollow sphere.
