Nano-SiO_2 with high activity and mesopores was prepared through sol-gel synthesis followed by low-temperatureheat treatment and ball milling firstly in our experiments. TEM was performed to measure particle sizes. Ni...Nano-SiO_2 with high activity and mesopores was prepared through sol-gel synthesis followed by low-temperatureheat treatment and ball milling firstly in our experiments. TEM was performed to measure particle sizes. Nitrogenadsorption experiments were carried out to estimate specific surface area, porous distribution and porous ratio by BETand BJH methods. The content of Si-OH in SiO_2 surface was calculated by analysis of the results of hydrogen-oxygencontent mensuration (HOCM). As a result, appropriate heat treatment system and ball milling time are important topreparation for nano-SiO_2 with high activity and mesopores, which are 5～50 nm particles, 5～6 nm average aperture,85%～93% porous ratio, and 51%～55% Si-OH content in surface. Nano-SiO_2 with that structure has high surfaceenergy and activity. This process, which has simple facilities and operation rules, is a new way of preparation fornano-SiO_2 with high activity and mesopores.展开更多
Nanosheets with mesopores on the surface have been prepared using molybdenum trioxide(α-MoO3).The effect of mesopores on the performance of the electrode remains elusive.The MoO3 nanosheets obtained in this study exh...Nanosheets with mesopores on the surface have been prepared using molybdenum trioxide(α-MoO3).The effect of mesopores on the performance of the electrode remains elusive.The MoO3 nanosheets obtained in this study exhibited great battery performance, including good capacity, prolonged recycling life cycles, and excellent rate performance;e.g., 780 mAh/g when charged under a super high current-density of 1000 m A/g.These nanosheets demonstrated excellent stability, maintaining a capacity of 1189 mAh/g after 20 cycles, and 1075 mAh/g after 50 cycles;thus preventing the capacity to decrease to values under the scanning rate of 100 mA/g.These high-purity MoO3 nanosheets are well-ordered and have dense mesopores on the surface;these micropores contribute to the excellent electrode performance of the host electrode materials;the performance parameters include prolonged battery life and capacity.Setting mesopores or active sites on the electrode surface can be an alternative way to obtain stable electrodes in the future.展开更多
The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur c...The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur cathodes,which have rarely been realized due to massive passivation and shuttling.Herein,microspheres of a carbon-carbon nitride composite(C@CN)with large mesopores are fabricated via molecular cooperative assembly.Using the C@CN-based electrodes,the effects of the large mesopores and N-functional groups on the electrochemical behavior of sulfur in LSB cells are thoroughly investigated under ultrahigh sulfur-loading conditions(>15 mgS cm^(-2)).Furthermore,for high-energy-density LSBs,the C@CN powders are pelletized into a thick free-standing electrode(thickness:500^m;diameter:11 mm)via a simple briquette process;here,the total amount of energy stored by the LSB cells is 39 mWh,corresponding to a volumetric energy density of 440 Wh L-1 with an areal capacity of 24.9 and 17.5 mAh cm^(-2) at 0.47 and 4.7 mA cm^(-2),respectively(at 24mgS cm^(-2)).These results have significantly surpassed most recent records due to the synergy among the large mesopores,(poly)sulfide-philic surfaces,and thick electrodes.The developed strategy with its potential for scale-up successfully fills the gap between laboratory-scale cells and practical cells without sacrificing the high areal capacity and high energy density,providing a solid foundation for the development of practical LSBs.展开更多
While hysteresis in the adsorption of fluids in porous material is known since about one century, the thermodynamic treatment of this phenomenon is still not settled. We propose to accept that thermodynamics is not de...While hysteresis in the adsorption of fluids in porous material is known since about one century, the thermodynamic treatment of this phenomenon is still not settled. We propose to accept that thermodynamics is not designed to deal with confined systems and we propose to introduce a new set of rules for describing the behavior of confined systems. This proposal is based on a large number of simulation calculations. The employed method of simulation has been shown to describe static and dynamic phenomena encountered in this field. The newly formulated theory incorporates the phenomenon of hysteresis without inconsistencies. Further, it will be shown that the theory allows simulating diffusional and convectional transport （nanofluidics） by a unified approach without the need to introduce capillary forces （surface or interface tensions） by phenomenological parameters. The second part of the paper is devoted to the potential for practical use. It turns out that the new concepts open the route to employing unusual states of matter found in porous systems which may lead to improved applications. In particular we will focus on the possibility to drive a fluid in a pore into states with negative pressure under static and under dynamic conditions. It turns out that states with negative pressure can be reproducibly controlled. Negative pressure states are in principal known since the time of Torricelli and they have been discussed in the literature as experimentally accessible situations. Still, they have not been turned into practical usefulness which is likely to be caused by the notion of their metastability in macroscopic systems. Possible applications refer to controlling chemical reactions as well as new routes to efficient separation processes that are difficult to handle by conventional techniques.展开更多
Pore size distribution（PSD） curves of synthesized hollow silica spheres with ultrmicropores and small mesopores were obtained from calculations based on the BJH,KJS,SF,MP,NLDFT models and Prof.Zhu＇s method.Comparis...Pore size distribution（PSD） curves of synthesized hollow silica spheres with ultrmicropores and small mesopores were obtained from calculations based on the BJH,KJS,SF,MP,NLDFT models and Prof.Zhu＇s method.Comparisons indicate that Zhu＇s method not only gives reasonable small mesopore size but also could be further extended to the ultramicropores region for the PSD evaluation.展开更多
When simulating the behavior of fluids in a stationary flow through mesopores we have observed a phenomenon that may prove useful in some cases as basis for separating fluid components. The scheme works at constant te...When simulating the behavior of fluids in a stationary flow through mesopores we have observed a phenomenon that may prove useful in some cases as basis for separating fluid components. The scheme works at constant temperature which makes it energy efficient as are other schemes like (molecular) sieves or chromatography. Sieves rely on differences in molecular size and chromatography on different affinity of components to the solid material of the ‘packing’. The scheme presented here may sometimes complement the established techniques in that it is based on a different mechanism. The fluids to be separated can have the same molecular size and the same affinity to solid material they are in contact with. The only requirement for the scheme to work is that the miscibility behavior varies somewhat with pressure or density. From literature it is known that virtually any mixture reacts on strong variations of pressure. Even a mixture that behaves almost ideally at ambient pressure will show slight deviations from ideal miscibility when exposed to extreme pressure. The strong differences in pressure are not created by external means but by exploiting the spontaneous behavior of fluids in mesopores. If the experiment is designed correctly, strong pressure gradients show up in mesopores that are far beyond any gradient that could be established by technical means. Our simulations are carried out for situations where pressure inside the pores varies between a few hundred bar positive pressure and a few hundred bar negative pressure while the pressure in the gas phase outside the pores amounts to ca.170 mbar.展开更多
An important feature of porous materials is the adsorption hysteresis: the amount of an atomic or molecular species adsorbed from the gas phase is not only dependent on the gas pressure, but may depend in certain rang...An important feature of porous materials is the adsorption hysteresis: the amount of an atomic or molecular species adsorbed from the gas phase is not only dependent on the gas pressure, but may depend in certain ranges of pressure on the history. Thus, the system may respond in different ways to identical experimental conditions which seems to contradict classical thermody-namics. While the phenomenon is known since about a century, it has not yet found a consistent theoretical description. In the pres-ent talk, we will-based on results of computer simulations-formulate rules that provide a consistent basis for the behavior of confined systems, or even for inhomogeneous systems in general. In other words, we present a new theory (confined thermodynamics) with its own definitions and rules. It will turn out, that hysteretic behavior does not impose a conceptual challenge any more, but follows in a natural way from these rules. The approach which is employed in the simulations is very akin to the density functional method. All quantities defined develop into the standard thermodynamic expressions when the density of amount becomes homogeneous.The second part of the talk is devoted to the potential for practical use. It turns out that the new theory does not only remove conceptual problems, but at the same time opens the route to a number of new states found in porous systems which may lead to im-proved applications. In particular we will focus on the possibility to drive a fluid in a pore into exotic states with negative pressure, provided one has full control over the phenomenon of adsorption hysteresis. Negative pressure states are in principal known since the time of Torricelli and they have been in the literature as experimentally accessible situations. Still, they have not been turned into practical usefulness which is likely to be caused by the notion of their metastability in macroscopic systems. However, fluids con-fined to nanopores have been proven to show reproducible behaviour. The present time appears to be suited for exploring the new ap-plications resting in fluid/pore systems: since about a decade material scientists have started to prepare pores with increasing accura-cy from an increasing variety of substances. On the other hand, the new theory presented in the first part of the talk provides the tool to drive a fluid/pore system reliably into any of the exotic states found within a hysteresis loop. Prospects of a few applications will be discussed.展开更多
Carbon deposition during methanol to hydrocarbons leads to the quick deactivation of ZSM-5 catalyst and it is one of the major problems for this technology. Decreasing the crystal size or introducing mesopores into ZS...Carbon deposition during methanol to hydrocarbons leads to the quick deactivation of ZSM-5 catalyst and it is one of the major problems for this technology. Decreasing the crystal size or introducing mesopores into ZSM-5 zeolites can improve its diffusion property and decrease the coke formation. In this paper, nano-sized ZSM-5 zeolite with intercrystalline mesopores combining the mesoporous and nano sized structure was fabricated. For comparison, the mesoporous ZSM-5 and nano-sized ZSM-5 were also prepared. These catalyst samples were characterized by XRD, BET, NH3-TPD, TEM, Py-IR and TG techniques and used on the conversion of methanol to gasoline in a fixed-bed reactor at T=405 degrees C, WHSV =4.74 h(-1) and P=1.0 MPa. It was found that the external surface area of the nano-sized ZSM-5 zeolite with intercrystalline mesopores reached 104 m(2)/g, larger than that of mesoporous ZSM-5 (66 m(2)/g) and nano sized ZSM-5 (76 m(2)/g). Catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores was 93 h, which was only longer than that of mesoporous ZSM-5 (86 h), but shorter than that of nano sized ZSM-5 (104 h). Strong acidity promoted the coke formation and thus decreased the catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores though it presented large external surface that could improve the diffusion property. The special zeolite catalyst was further dealuminated to decrease the strong acidity. After this, its coke formation rate was slowed and catalytic lifetime was prolonged to 106 h because of the large external surface area and decreased weak acidity. This special structural zeolite is a potential catalyst for methanol to gasoline reaction. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.展开更多
Bio-inspired hierarchical self-assembly provides elegant and powerful bottom-up strategies for the creation of complex materials.However,the current self-assembly approaches for natural bio-compounds often result in m...Bio-inspired hierarchical self-assembly provides elegant and powerful bottom-up strategies for the creation of complex materials.However,the current self-assembly approaches for natural bio-compounds often result in materials with limited diversity and complexity in architecture as well as microstructure.Here,we develop a novel coordination polymerization-driven hierarchical assembly of micelle strategy,using phytic acid-based natural compounds as an example,for the spatially controlled fabrication of metal coordination bio-derived polymers.The resultant ferric phytate polymer nanospheres feature hollow architecture,ordered meso-channels of^12 nm,high surface area of 401 m2 g−1,and large pore volume of 0.53 cm3 g−1.As an advanced anode material,this bio-derivative polymer delivers a remarkable reversible capacity of 540 mAh g−1 at 50 mA g−1,good rate capability,and cycling stability for sodium-ion batteries.This study holds great potential of the design of new complex bio-materials with supramolecular chemistry.展开更多
ZSM-48 zeolites with various Si/Al ratios were hydrothermally synthesized in the H;N（CH;）;NH;（HDA）-containing media. The obtained samples were highly crystallized with minor mixed phases as evidenced by X-ray powd...ZSM-48 zeolites with various Si/Al ratios were hydrothermally synthesized in the H;N（CH;）;NH;（HDA）-containing media. The obtained samples were highly crystallized with minor mixed phases as evidenced by X-ray powder diffraction（XRD）. The alkaline treated ZSM-48 zeolites maintained its structure under different concentrations of Na OH aqueous solution. Micropores remained unchanged while mesopores with wide pore size distribution formed after the alkaline treatment. The surface area increased from 228 to 288 m;/g. The Br?nsted acid sites had little alteration while an obvious increase of Lewis acid sites was observed. The hydroisomerization of hexadecane was performed as the model reaction to test the effects of the alkali treatment. The conversion of hexadecane had almost no change, which was attributed to the preservation of the Br?nsted acid sites. While high selectivity to iso-hexadecane with an improved iso to normal ratio of alkanes was due to the mesopore formation and improved diffusivity.展开更多
The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 w...The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.展开更多
ZSM-5 aggregates consisting of superfine and hierarchical nanocrystals(combined with micropores and intra-crystalline mesopores) with an average size of 30 nm were prepared through one-pot synthesis with the assistanc...ZSM-5 aggregates consisting of superfine and hierarchical nanocrystals(combined with micropores and intra-crystalline mesopores) with an average size of 30 nm were prepared through one-pot synthesis with the assistance of anionic polyacrylamide(APAM). The resultant zeolites(AHN-ZSM-5) were characterized by XRD, ICP-OES, SEM, TEM, BET, NH_3-TPD, Py-IR, and TG analyses and evaluated in the methanol to gasoline(MTG) reaction. Characterization results show that the hierarchical ZSM-5 aggregates possessed two kinds of mesopores, namely inter-and intra-crystalline mesopores. The amount of APAM considerably influenced the mesoporosity and textural properties of AHN-ZSM-5 zeolites. With the addition of APAM in the synthesis, the AHN-ZSM-5 zeolites exhibited large mesopore volume, large external surface area, and appropriate acidity. When applied in the MTG reaction, AHN-ZSM-5 demonstrated a catalytic lifetime that was 1.6 times longer than that of conventional ZSM-5 synthesized in the absence of APAM.展开更多
Designing Fischer-Tropsch synthesis(FTS)catalysts to selectively produce liquid hydrocarbon fuels is a crucial challenge.Herein,we selectively introduced Co nanoparticles(NPs)into the micropores and mesopores of an or...Designing Fischer-Tropsch synthesis(FTS)catalysts to selectively produce liquid hydrocarbon fuels is a crucial challenge.Herein,we selectively introduced Co nanoparticles(NPs)into the micropores and mesopores of an ordered mesoporous MFI zeolite(OMMZ)through impregnation,which controlled the carbon number distribution in the FTS products by tuning the position of catalytic active sites in differently sized pores.The Co precursors coordinated by acetate with a size of 9.4×4.2×2.5Åand by 2,2‘-bipyridine with a size of 9.5×8.7×7.9Å,smaller and larger than the micropores(ca.5.5Å)of MFI,made the Co species incorporated in OMMZ's micropores and mesopores,respectively.The carbon number products synthesized with the Co NPs confined in mesopores were larger than that in micropores.The high jet and diesel selectivities of 66.5%and 65.3%were achieved with Co NPs confined in micropores and mesopores of less acidic Na-type OMMZ,respectively.Gasoline and jet selectivities of 76.7%and 70.8%were achieved with Co NPs confined in micropores and mesopores of H-type OMMZ with Brönsted acid sites,respectively.A series of characterizations revealed that the selective production of diesel and jet fuels was due to the C-C cleavage suppressing of heavier hydrocarbons by the Co NPs located in mesopores.展开更多
The porous structure of alumina is influenced by various factors during the synthesis process.In this study,we proposed a gas-liquid interfacial deposition method,different from conventional liquid-phase reactions,whi...The porous structure of alumina is influenced by various factors during the synthesis process.In this study,we proposed a gas-liquid interfacial deposition method,different from conventional liquid-phase reactions,which effectively slows down the precipitation rate,facilitating the investigation of the pore structure and morphology changes of alumina during the synthesis process.Ammonia (NH3);carbon dioxide (CO_(2)) generated by the decomposition of inorganic ammonium salts constitute the gas phase,while the aqueous solution of the inorganic aluminum salt serves as the liquid phase.The gas diffuses,contacts,dissolves and reacts with the inorganic aluminum salt solution,constructing a platform for gas-liquid interfacial deposition at the gas-liquid interface.We precisely regulated the critical factors that affected the precipitation rate during the reaction process,such as gas-liquid reaction methods,precipitant types,aluminum salt types,and reaction temperatures,leading to systematic changes in the pore structures of the obtained alumina.After considering the influence of precipitation rate,pH value,and anion types,we found that the fundamental factor affecting pore structure lies in the water content of the precursors.By controlling the phase and crystallinity of the precursors,alumina with a large mesopore size distribution concentrated at 25.3 nm can be obtained.展开更多
To investigate the influence of mesopores towards the solidification of self-microemulsifying drug delivery system(SMEDDS), mesoporous silica nanospheres(MSNs) and Santa Barbara Amorphous-15(SBA-15) were compared. The...To investigate the influence of mesopores towards the solidification of self-microemulsifying drug delivery system(SMEDDS), mesoporous silica nanospheres(MSNs) and Santa Barbara Amorphous-15(SBA-15) were compared. The MSNs had hydrodynamic size of 195.35 ± 5.82 nm, and pore diameter of 2.70 nm. The SBA-15 had hydrodynamic size of 2312.19 ± 106.93 nm, and pore diameter of 10.91 nm. The MSNs and SBA-15 showed similar loading efficiency of SMEDDS containing sirolimus(SRL). However,MSNs had higher drug dissolution and in vivo absorption, with relative bioavailability of 174.62%. Thus,the length of mesopores played a more important role in solidification of SMEDDS as compared with the pore diameter. This study suggests that the SMEDDS-MSNs can be a potential candidate for oral administration of hydrophobic drugs.展开更多
Hierarchical ZSM-5 zeolite with radial mesopores is controllably synthesized using piperidine in a NaOH solution.The piperidine molecules enter the zeolite micropores and protect the zeolite framework from extensive d...Hierarchical ZSM-5 zeolite with radial mesopores is controllably synthesized using piperidine in a NaOH solution.The piperidine molecules enter the zeolite micropores and protect the zeolite framework from extensive desilication.The areas containing fewer aluminum atoms contain fewer piperidine protectant molecules and so they dissolve first.Small amounts of mesopores are then gradually generated in areas with more aluminum atoms and more piperidine protectant.In this manner,radial mesopores are formed in the ZSM-5 zeolite with a maximal preservation of the micropores and active sites.The optimal hierarchical ZSM-5 zeolite,prepared with a molar ratio of piperidine to zeolite of 0.03,had a mesopore surface area of 136 m·g and a solid yield of 80%.The incorporation of the radial mesopores results in micropores that are interconnected which shortened the average diffusion path length.Compared to the parent zeolite,the hierarchical ZSM-5 zeolite possesses more accessible acid sites and has a higher catalytic activity and a longer lifetime for the alkylation of benzene.展开更多
We prepare CdS/CdSe/ZnS thin films by successive ionic layer adsorption and reaction method. Results show a wider photoresponse range of TiO2 mesopores from the ultraviolet region to the visible light region. Sequenti...We prepare CdS/CdSe/ZnS thin films by successive ionic layer adsorption and reaction method. Results show a wider photoresponse range of TiO2 mesopores from the ultraviolet region to the visible light region. Sequentially assembled CdS/CdSe/ZnS quantum and photocurrent efficiency. A high efficiency of dots exhibit significantly improved light-harvesting ability 1.059354% is obtained.展开更多
CO_(2)-to-CO electrolyzer technology converts carbon dioxide into carbon monoxide using electrochemical methods,offering significant environmental and energy benefits by aiding in greenhouse gas mitigation and promoti...CO_(2)-to-CO electrolyzer technology converts carbon dioxide into carbon monoxide using electrochemical methods,offering significant environmental and energy benefits by aiding in greenhouse gas mitigation and promoting a carbon circular economy.Recent study by Strasser et al.in Nature Chemical Engineering presents a high-performance CO_(2)-to-CO electrolyzer utilizing a NiNC catalyst with nearly 100%faradaic efficiency,employing innovative diagnostic tools like the carbon crossover coefficient(CCC)to address transport-related failures and optimize overall efficiency.Strasser’s research demonstrates the potential of NiNC catalysts,particularly NiNC-IMI,for efficient CO production in CO_(2)-to-CO electrolyzers,highlighting their high selectivity and performance.However,challenges such as localized CO_(2)depletion and mass transport limitations underscore the need for further optimization and development of diagnostic tools like CCC.Strategies for optimizing catalyst structure and operational parameters offer avenues for enhancing the performance and reliability of electrochemical CO_(2)reduction catalysts.展开更多
Hollow metal-organic frameworks(MOFs)and their derivatives have attracted more and more attention due to their high specific surface area and perfect morphological structure,which determine their large potential appli...Hollow metal-organic frameworks(MOFs)and their derivatives have attracted more and more attention due to their high specific surface area and perfect morphological structure,which determine their large potential application in energy storage and catalysis fields.However,few researchers have carried out further modification on the outer shell of hollow MOFs,such as the perforation modification,which will endow hollow nanomaterials derived from MOFs with multifunctionality.In this paper,hollow MOFs of MIL-53(Fe)with perforated outer surface are successfully synthesized by using SiO2 nanospheres as the template via a self-assembly process induced by the coordination polymerization.The tightly packed mesopore structure makes the carbon outer shell of MOFs thinner,thus realizing the in-situ transformation from MOFs to hollow Fe3 O4/carbon,which exhibits perfect capacity approaching 1270 mA h g-1 even after 200 cycles at 0.1 A g-1,as an anode material in lithium ion batteries(LIBs)application.This research provides a new strategy for the design and preparation of MOFs and their derivatives with multifunctionality for the energy applications.展开更多
Carbon nanosheets with a tunable mesopore size, large pore volume, and good electronic conductivity are synthesized via a solution-chemistry approach. In this synthesis, diaminohexane and graphene oxide （GO） are use...Carbon nanosheets with a tunable mesopore size, large pore volume, and good electronic conductivity are synthesized via a solution-chemistry approach. In this synthesis, diaminohexane and graphene oxide （GO） are used as the structural directing agents, and a silica colloid is used as a mesopores template. Diaminohexane plays a crucial role in bridging silica colloid particles and GO, as well as initiating the polymerization of benzoxazine on the surfaces of both the GO and silica, resulting in the formation of a hybrid nanosheet polymer. The carbon nanosheets have graphene embedded in them and have several spherical mesopores with a pore volume up to 3.5 cm^3·g^-1 on their surfaces. These nuerous accessible mesopores in the carbon layers can act as reservoirs to host a high loading of active charge-storage materials with good dispersion and a uniform particle size. Compared with active materials with wide particle-size distributions, the unique proposed configuration with confined and uniform particles exhibits superior electrochemical performance during lithiation and delithiation, espedaUy during long cycles and at high rates.展开更多
文摘Nano-SiO_2 with high activity and mesopores was prepared through sol-gel synthesis followed by low-temperatureheat treatment and ball milling firstly in our experiments. TEM was performed to measure particle sizes. Nitrogenadsorption experiments were carried out to estimate specific surface area, porous distribution and porous ratio by BETand BJH methods. The content of Si-OH in SiO_2 surface was calculated by analysis of the results of hydrogen-oxygencontent mensuration (HOCM). As a result, appropriate heat treatment system and ball milling time are important topreparation for nano-SiO_2 with high activity and mesopores, which are 5～50 nm particles, 5～6 nm average aperture,85%～93% porous ratio, and 51%～55% Si-OH content in surface. Nano-SiO_2 with that structure has high surfaceenergy and activity. This process, which has simple facilities and operation rules, is a new way of preparation fornano-SiO_2 with high activity and mesopores.
基金financially supported by the National Natural Science Foundation of China (No.51771125)。
文摘Nanosheets with mesopores on the surface have been prepared using molybdenum trioxide(α-MoO3).The effect of mesopores on the performance of the electrode remains elusive.The MoO3 nanosheets obtained in this study exhibited great battery performance, including good capacity, prolonged recycling life cycles, and excellent rate performance;e.g., 780 mAh/g when charged under a super high current-density of 1000 m A/g.These nanosheets demonstrated excellent stability, maintaining a capacity of 1189 mAh/g after 20 cycles, and 1075 mAh/g after 50 cycles;thus preventing the capacity to decrease to values under the scanning rate of 100 mA/g.These high-purity MoO3 nanosheets are well-ordered and have dense mesopores on the surface;these micropores contribute to the excellent electrode performance of the host electrode materials;the performance parameters include prolonged battery life and capacity.Setting mesopores or active sites on the electrode surface can be an alternative way to obtain stable electrodes in the future.
基金the R&D Convergence Program of NST(National Research Council of Science&Technology)of the Republic of Korea(CAP-15-02-KBSI)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(MSIT)(No.2019R1C1C1007745)a National Research Foundation of Korea(NRF)grant funded by the Korean Government(Ministry of Science,ICT&Future Planning)(No.2019R1A4A2001527).
文摘The development of sulfur cathodes with high areal capacity and high energy density is crucial for the practical application of lithium-sulfur batteries(LSBs).LSBs can be built by employing(ultra)high-loading sulfur cathodes,which have rarely been realized due to massive passivation and shuttling.Herein,microspheres of a carbon-carbon nitride composite(C@CN)with large mesopores are fabricated via molecular cooperative assembly.Using the C@CN-based electrodes,the effects of the large mesopores and N-functional groups on the electrochemical behavior of sulfur in LSB cells are thoroughly investigated under ultrahigh sulfur-loading conditions(>15 mgS cm^(-2)).Furthermore,for high-energy-density LSBs,the C@CN powders are pelletized into a thick free-standing electrode(thickness:500^m;diameter:11 mm)via a simple briquette process;here,the total amount of energy stored by the LSB cells is 39 mWh,corresponding to a volumetric energy density of 440 Wh L-1 with an areal capacity of 24.9 and 17.5 mAh cm^(-2) at 0.47 and 4.7 mA cm^(-2),respectively(at 24mgS cm^(-2)).These results have significantly surpassed most recent records due to the synergy among the large mesopores,(poly)sulfide-philic surfaces,and thick electrodes.The developed strategy with its potential for scale-up successfully fills the gap between laboratory-scale cells and practical cells without sacrificing the high areal capacity and high energy density,providing a solid foundation for the development of practical LSBs.
基金The theoretical basis of this study has been developed with financial support by the German Science Foundation under grant Mo288/26 within the Priority program 1105 ＂Non equilibrium processes in Fluid/fluid systems＂. Dr. Yves-Gorat Stommel has contributed to the application part of the paper by motivating calculations on separation and by critical comments.
文摘While hysteresis in the adsorption of fluids in porous material is known since about one century, the thermodynamic treatment of this phenomenon is still not settled. We propose to accept that thermodynamics is not designed to deal with confined systems and we propose to introduce a new set of rules for describing the behavior of confined systems. This proposal is based on a large number of simulation calculations. The employed method of simulation has been shown to describe static and dynamic phenomena encountered in this field. The newly formulated theory incorporates the phenomenon of hysteresis without inconsistencies. Further, it will be shown that the theory allows simulating diffusional and convectional transport （nanofluidics） by a unified approach without the need to introduce capillary forces （surface or interface tensions） by phenomenological parameters. The second part of the paper is devoted to the potential for practical use. It turns out that the new concepts open the route to employing unusual states of matter found in porous systems which may lead to improved applications. In particular we will focus on the possibility to drive a fluid in a pore into states with negative pressure under static and under dynamic conditions. It turns out that states with negative pressure can be reproducibly controlled. Negative pressure states are in principal known since the time of Torricelli and they have been discussed in the literature as experimentally accessible situations. Still, they have not been turned into practical usefulness which is likely to be caused by the notion of their metastability in macroscopic systems. Possible applications refer to controlling chemical reactions as well as new routes to efficient separation processes that are difficult to handle by conventional techniques.
基金Sponsored by Scientific Research Foundation for Returned Overseas Chinese Scholars,State Education Ministrysupported by the NFSC(No. 50672052)
文摘Pore size distribution（PSD） curves of synthesized hollow silica spheres with ultrmicropores and small mesopores were obtained from calculations based on the BJH,KJS,SF,MP,NLDFT models and Prof.Zhu＇s method.Comparisons indicate that Zhu＇s method not only gives reasonable small mesopore size but also could be further extended to the ultramicropores region for the PSD evaluation.
文摘When simulating the behavior of fluids in a stationary flow through mesopores we have observed a phenomenon that may prove useful in some cases as basis for separating fluid components. The scheme works at constant temperature which makes it energy efficient as are other schemes like (molecular) sieves or chromatography. Sieves rely on differences in molecular size and chromatography on different affinity of components to the solid material of the ‘packing’. The scheme presented here may sometimes complement the established techniques in that it is based on a different mechanism. The fluids to be separated can have the same molecular size and the same affinity to solid material they are in contact with. The only requirement for the scheme to work is that the miscibility behavior varies somewhat with pressure or density. From literature it is known that virtually any mixture reacts on strong variations of pressure. Even a mixture that behaves almost ideally at ambient pressure will show slight deviations from ideal miscibility when exposed to extreme pressure. The strong differences in pressure are not created by external means but by exploiting the spontaneous behavior of fluids in mesopores. If the experiment is designed correctly, strong pressure gradients show up in mesopores that are far beyond any gradient that could be established by technical means. Our simulations are carried out for situations where pressure inside the pores varies between a few hundred bar positive pressure and a few hundred bar negative pressure while the pressure in the gas phase outside the pores amounts to ca.170 mbar.
文摘An important feature of porous materials is the adsorption hysteresis: the amount of an atomic or molecular species adsorbed from the gas phase is not only dependent on the gas pressure, but may depend in certain ranges of pressure on the history. Thus, the system may respond in different ways to identical experimental conditions which seems to contradict classical thermody-namics. While the phenomenon is known since about a century, it has not yet found a consistent theoretical description. In the pres-ent talk, we will-based on results of computer simulations-formulate rules that provide a consistent basis for the behavior of confined systems, or even for inhomogeneous systems in general. In other words, we present a new theory (confined thermodynamics) with its own definitions and rules. It will turn out, that hysteretic behavior does not impose a conceptual challenge any more, but follows in a natural way from these rules. The approach which is employed in the simulations is very akin to the density functional method. All quantities defined develop into the standard thermodynamic expressions when the density of amount becomes homogeneous.The second part of the talk is devoted to the potential for practical use. It turns out that the new theory does not only remove conceptual problems, but at the same time opens the route to a number of new states found in porous systems which may lead to im-proved applications. In particular we will focus on the possibility to drive a fluid in a pore into exotic states with negative pressure, provided one has full control over the phenomenon of adsorption hysteresis. Negative pressure states are in principal known since the time of Torricelli and they have been in the literature as experimentally accessible situations. Still, they have not been turned into practical usefulness which is likely to be caused by the notion of their metastability in macroscopic systems. However, fluids con-fined to nanopores have been proven to show reproducible behaviour. The present time appears to be suited for exploring the new ap-plications resting in fluid/pore systems: since about a decade material scientists have started to prepare pores with increasing accura-cy from an increasing variety of substances. On the other hand, the new theory presented in the first part of the talk provides the tool to drive a fluid/pore system reliably into any of the exotic states found within a hysteresis loop. Prospects of a few applications will be discussed.
基金the Science and Technology Foundation Platform Construction Project of Shanxi Province(No.2015091009)the National Science Foundation for Young Scientists of China(No.21606160)+1 种基金the Qualified Personnel Foundation of Taiyuan University of Technology(No.tyut-rc201454a)School Fund of Taiyuan University of Technology(Nos.1205-04020202 and 1205-04020102)
文摘Carbon deposition during methanol to hydrocarbons leads to the quick deactivation of ZSM-5 catalyst and it is one of the major problems for this technology. Decreasing the crystal size or introducing mesopores into ZSM-5 zeolites can improve its diffusion property and decrease the coke formation. In this paper, nano-sized ZSM-5 zeolite with intercrystalline mesopores combining the mesoporous and nano sized structure was fabricated. For comparison, the mesoporous ZSM-5 and nano-sized ZSM-5 were also prepared. These catalyst samples were characterized by XRD, BET, NH3-TPD, TEM, Py-IR and TG techniques and used on the conversion of methanol to gasoline in a fixed-bed reactor at T=405 degrees C, WHSV =4.74 h(-1) and P=1.0 MPa. It was found that the external surface area of the nano-sized ZSM-5 zeolite with intercrystalline mesopores reached 104 m(2)/g, larger than that of mesoporous ZSM-5 (66 m(2)/g) and nano sized ZSM-5 (76 m(2)/g). Catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores was 93 h, which was only longer than that of mesoporous ZSM-5 (86 h), but shorter than that of nano sized ZSM-5 (104 h). Strong acidity promoted the coke formation and thus decreased the catalytic lifetime of the nano-sized ZSM-5 zeolite with intercrystalline mesopores though it presented large external surface that could improve the diffusion property. The special zeolite catalyst was further dealuminated to decrease the strong acidity. After this, its coke formation rate was slowed and catalytic lifetime was prolonged to 106 h because of the large external surface area and decreased weak acidity. This special structural zeolite is a potential catalyst for methanol to gasoline reaction. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.
基金financially supported by the Natural Science Foundation of China (Grant Nos.51773062 and 61831021)
文摘Bio-inspired hierarchical self-assembly provides elegant and powerful bottom-up strategies for the creation of complex materials.However,the current self-assembly approaches for natural bio-compounds often result in materials with limited diversity and complexity in architecture as well as microstructure.Here,we develop a novel coordination polymerization-driven hierarchical assembly of micelle strategy,using phytic acid-based natural compounds as an example,for the spatially controlled fabrication of metal coordination bio-derived polymers.The resultant ferric phytate polymer nanospheres feature hollow architecture,ordered meso-channels of^12 nm,high surface area of 401 m2 g−1,and large pore volume of 0.53 cm3 g−1.As an advanced anode material,this bio-derivative polymer delivers a remarkable reversible capacity of 540 mAh g−1 at 50 mA g−1,good rate capability,and cycling stability for sodium-ion batteries.This study holds great potential of the design of new complex bio-materials with supramolecular chemistry.
基金supported by the National Natural Science Foundation of China(21073023)
文摘ZSM-48 zeolites with various Si/Al ratios were hydrothermally synthesized in the H;N（CH;）;NH;（HDA）-containing media. The obtained samples were highly crystallized with minor mixed phases as evidenced by X-ray powder diffraction（XRD）. The alkaline treated ZSM-48 zeolites maintained its structure under different concentrations of Na OH aqueous solution. Micropores remained unchanged while mesopores with wide pore size distribution formed after the alkaline treatment. The surface area increased from 228 to 288 m;/g. The Br?nsted acid sites had little alteration while an obvious increase of Lewis acid sites was observed. The hydroisomerization of hexadecane was performed as the model reaction to test the effects of the alkali treatment. The conversion of hexadecane had almost no change, which was attributed to the preservation of the Br?nsted acid sites. While high selectivity to iso-hexadecane with an improved iso to normal ratio of alkanes was due to the mesopore formation and improved diffusivity.
文摘The simultaneous removal of up to 92% of the surfactant template and chemical implantation of transition metal complexes into mesopores has been successfully achieved by treating as-synthesized pure siliceous MCM-41 with supercritical CO2 modified with CH2Cl2/MeOH mixture, resulting in the formation of functionalized material with uniform pore structure.
基金supported by the National Natural Science Foundation of China (No. 21276183)
文摘ZSM-5 aggregates consisting of superfine and hierarchical nanocrystals(combined with micropores and intra-crystalline mesopores) with an average size of 30 nm were prepared through one-pot synthesis with the assistance of anionic polyacrylamide(APAM). The resultant zeolites(AHN-ZSM-5) were characterized by XRD, ICP-OES, SEM, TEM, BET, NH_3-TPD, Py-IR, and TG analyses and evaluated in the methanol to gasoline(MTG) reaction. Characterization results show that the hierarchical ZSM-5 aggregates possessed two kinds of mesopores, namely inter-and intra-crystalline mesopores. The amount of APAM considerably influenced the mesoporosity and textural properties of AHN-ZSM-5 zeolites. With the addition of APAM in the synthesis, the AHN-ZSM-5 zeolites exhibited large mesopore volume, large external surface area, and appropriate acidity. When applied in the MTG reaction, AHN-ZSM-5 demonstrated a catalytic lifetime that was 1.6 times longer than that of conventional ZSM-5 synthesized in the absence of APAM.
文摘Designing Fischer-Tropsch synthesis(FTS)catalysts to selectively produce liquid hydrocarbon fuels is a crucial challenge.Herein,we selectively introduced Co nanoparticles(NPs)into the micropores and mesopores of an ordered mesoporous MFI zeolite(OMMZ)through impregnation,which controlled the carbon number distribution in the FTS products by tuning the position of catalytic active sites in differently sized pores.The Co precursors coordinated by acetate with a size of 9.4×4.2×2.5Åand by 2,2‘-bipyridine with a size of 9.5×8.7×7.9Å,smaller and larger than the micropores(ca.5.5Å)of MFI,made the Co species incorporated in OMMZ's micropores and mesopores,respectively.The carbon number products synthesized with the Co NPs confined in mesopores were larger than that in micropores.The high jet and diesel selectivities of 66.5%and 65.3%were achieved with Co NPs confined in micropores and mesopores of less acidic Na-type OMMZ,respectively.Gasoline and jet selectivities of 76.7%and 70.8%were achieved with Co NPs confined in micropores and mesopores of H-type OMMZ with Brönsted acid sites,respectively.A series of characterizations revealed that the selective production of diesel and jet fuels was due to the C-C cleavage suppressing of heavier hydrocarbons by the Co NPs located in mesopores.
基金supported by the National Key Research and Development Project of China(Nos.2021YFA1500301,2018YFA0209404).
文摘The porous structure of alumina is influenced by various factors during the synthesis process.In this study,we proposed a gas-liquid interfacial deposition method,different from conventional liquid-phase reactions,which effectively slows down the precipitation rate,facilitating the investigation of the pore structure and morphology changes of alumina during the synthesis process.Ammonia (NH3);carbon dioxide (CO_(2)) generated by the decomposition of inorganic ammonium salts constitute the gas phase,while the aqueous solution of the inorganic aluminum salt serves as the liquid phase.The gas diffuses,contacts,dissolves and reacts with the inorganic aluminum salt solution,constructing a platform for gas-liquid interfacial deposition at the gas-liquid interface.We precisely regulated the critical factors that affected the precipitation rate during the reaction process,such as gas-liquid reaction methods,precipitant types,aluminum salt types,and reaction temperatures,leading to systematic changes in the pore structures of the obtained alumina.After considering the influence of precipitation rate,pH value,and anion types,we found that the fundamental factor affecting pore structure lies in the water content of the precursors.By controlling the phase and crystallinity of the precursors,alumina with a large mesopore size distribution concentrated at 25.3 nm can be obtained.
基金supported by the Natural Science Foundation of Fujian Province(Nos.2017J01822 and 2018J01347)Fujian Medical University(No.2017XQ1202)Fuzhou General Hospital(No.2017Q06)
文摘To investigate the influence of mesopores towards the solidification of self-microemulsifying drug delivery system(SMEDDS), mesoporous silica nanospheres(MSNs) and Santa Barbara Amorphous-15(SBA-15) were compared. The MSNs had hydrodynamic size of 195.35 ± 5.82 nm, and pore diameter of 2.70 nm. The SBA-15 had hydrodynamic size of 2312.19 ± 106.93 nm, and pore diameter of 10.91 nm. The MSNs and SBA-15 showed similar loading efficiency of SMEDDS containing sirolimus(SRL). However,MSNs had higher drug dissolution and in vivo absorption, with relative bioavailability of 174.62%. Thus,the length of mesopores played a more important role in solidification of SMEDDS as compared with the pore diameter. This study suggests that the SMEDDS-MSNs can be a potential candidate for oral administration of hydrophobic drugs.
基金the National Key Research and Development Program of China(Grant No.2017YFB0702800)China Postdoctoral Science Foundation(2016M600347).
文摘Hierarchical ZSM-5 zeolite with radial mesopores is controllably synthesized using piperidine in a NaOH solution.The piperidine molecules enter the zeolite micropores and protect the zeolite framework from extensive desilication.The areas containing fewer aluminum atoms contain fewer piperidine protectant molecules and so they dissolve first.Small amounts of mesopores are then gradually generated in areas with more aluminum atoms and more piperidine protectant.In this manner,radial mesopores are formed in the ZSM-5 zeolite with a maximal preservation of the micropores and active sites.The optimal hierarchical ZSM-5 zeolite,prepared with a molar ratio of piperidine to zeolite of 0.03,had a mesopore surface area of 136 m·g and a solid yield of 80%.The incorporation of the radial mesopores results in micropores that are interconnected which shortened the average diffusion path length.Compared to the parent zeolite,the hierarchical ZSM-5 zeolite possesses more accessible acid sites and has a higher catalytic activity and a longer lifetime for the alkylation of benzene.
基金supported by the University of Science of Ho Chi Munh City and Dongthap University
文摘We prepare CdS/CdSe/ZnS thin films by successive ionic layer adsorption and reaction method. Results show a wider photoresponse range of TiO2 mesopores from the ultraviolet region to the visible light region. Sequentially assembled CdS/CdSe/ZnS quantum and photocurrent efficiency. A high efficiency of dots exhibit significantly improved light-harvesting ability 1.059354% is obtained.
基金the University of Oxford for the Mathematical, Physical and Life Sciences Division (MPLS) Enterprise and Innovation Fellowshipthe support of Massachusetts Institute of Technology+1 种基金the support of the National Key R&D Program of China (2021YFB3801600)the National Natural Science Foundation of China (22325204)。
文摘CO_(2)-to-CO electrolyzer technology converts carbon dioxide into carbon monoxide using electrochemical methods,offering significant environmental and energy benefits by aiding in greenhouse gas mitigation and promoting a carbon circular economy.Recent study by Strasser et al.in Nature Chemical Engineering presents a high-performance CO_(2)-to-CO electrolyzer utilizing a NiNC catalyst with nearly 100%faradaic efficiency,employing innovative diagnostic tools like the carbon crossover coefficient(CCC)to address transport-related failures and optimize overall efficiency.Strasser’s research demonstrates the potential of NiNC catalysts,particularly NiNC-IMI,for efficient CO production in CO_(2)-to-CO electrolyzers,highlighting their high selectivity and performance.However,challenges such as localized CO_(2)depletion and mass transport limitations underscore the need for further optimization and development of diagnostic tools like CCC.Strategies for optimizing catalyst structure and operational parameters offer avenues for enhancing the performance and reliability of electrochemical CO_(2)reduction catalysts.
基金supported by the State Key Research Development Program of China(2016YFA0204200)The National Natural Science Foundation of China(21822603,21811540394,5171101651,21677048,21773062,and 21577036)+1 种基金Shanghai Pujiang Program(17PJD011)the Fundamental Research Funds for the Central Universities(22A201514021).
文摘Hollow metal-organic frameworks(MOFs)and their derivatives have attracted more and more attention due to their high specific surface area and perfect morphological structure,which determine their large potential application in energy storage and catalysis fields.However,few researchers have carried out further modification on the outer shell of hollow MOFs,such as the perforation modification,which will endow hollow nanomaterials derived from MOFs with multifunctionality.In this paper,hollow MOFs of MIL-53(Fe)with perforated outer surface are successfully synthesized by using SiO2 nanospheres as the template via a self-assembly process induced by the coordination polymerization.The tightly packed mesopore structure makes the carbon outer shell of MOFs thinner,thus realizing the in-situ transformation from MOFs to hollow Fe3 O4/carbon,which exhibits perfect capacity approaching 1270 mA h g-1 even after 200 cycles at 0.1 A g-1,as an anode material in lithium ion batteries(LIBs)application.This research provides a new strategy for the design and preparation of MOFs and their derivatives with multifunctionality for the energy applications.
文摘Carbon nanosheets with a tunable mesopore size, large pore volume, and good electronic conductivity are synthesized via a solution-chemistry approach. In this synthesis, diaminohexane and graphene oxide （GO） are used as the structural directing agents, and a silica colloid is used as a mesopores template. Diaminohexane plays a crucial role in bridging silica colloid particles and GO, as well as initiating the polymerization of benzoxazine on the surfaces of both the GO and silica, resulting in the formation of a hybrid nanosheet polymer. The carbon nanosheets have graphene embedded in them and have several spherical mesopores with a pore volume up to 3.5 cm^3·g^-1 on their surfaces. These nuerous accessible mesopores in the carbon layers can act as reservoirs to host a high loading of active charge-storage materials with good dispersion and a uniform particle size. Compared with active materials with wide particle-size distributions, the unique proposed configuration with confined and uniform particles exhibits superior electrochemical performance during lithiation and delithiation, espedaUy during long cycles and at high rates.
