Showing papers on "Mesoporous material published in 2014"
TL;DR: In-situ transmission electron microscopy and continuum media mechanical calculations are combined to demonstrate that large (>20 μm) mesoporous silicon sponge prepared by the anodization method can limit the particle volume expansion at full lithiation to ~30% and prevent pulverization in bulk silicon particles.
Abstract: Silicon is a promising anode material for lithium ion batteries, but suffers from poor cyclability especially at high mass loading. Here, Li et al. synthesize mesoporous silicon sponge-like structures, which show promising performance at the deep lithiation and high loading conditions required for practical applications.
1,145 citations
TL;DR: This work reports the preparation of 6 nm-sized nanoparticles of this type by a simple and fast method based on the use of an ammonium bromide with a medium-sized chain that keeps the nanoparticles dispersed in a wide range of organic solvents.
Abstract: To date, there is no example in the literature of free, nanometer-sized, organolead halide CH3NH3PbBr3 perovskites. We report here the preparation of 6 nm-sized nanoparticles of this type by a simple and fast method based on the use of an ammonium bromide with a medium-sized chain that keeps the nanoparticles dispersed in a wide range of organic solvents. These nanoparticles can be maintained stable in the solid state as well as in concentrated solutions for more than three months, without requiring a mesoporous material. This makes it possible to prepare homogeneous thin films of these nanoparticles by spin-coating on a quartz substrate. Both the colloidal solution and the thin film emit light within a narrow bandwidth of the visible spectrum and with a high quantum yield (ca. 20%); this could be advantageous in the design of optoelectronic devices.
1,090 citations
TL;DR: The facile synthesis of ordered mesoporous black TiO2 (OMBT) materials, which exhibit excellent photocatalytic hydrogen evolution performances and can extend the photoresponse from ultraviolet to visible and infrared light regions and exhibit a high solar-driven hydrogen production rate.
Abstract: Mesoporous TiO2 has gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. Herein, we report the facile synthesis of ordered mesoporous black TiO2 (OMBT) materials, which exhibit excellent photocatalytic hydrogen evolution performances. In this case, the employment of a thermally stable and high-surface-area mesoporous TiO2 as the hydrogenation precursor is the key for fabricating the OMBT materials, which not only facilitate H2 gas diffusion into TiO2 and interaction with their structures but also maintain the ordered mesoporous structures as well as inhibit the phase transformation (from anatase to rutile) and crystal growth during hydrogenation at 500 °C. The resultant OMBT materials possess a relatively high surface area of ∼124 m2 g–1 and a large pore size and pore volume of ∼9.6 nm and 0.24 cm3 g–1, respectively. More importantly, the OMBT materials can extend the photoresponse from ultraviolet to visible and infrared light regions and ...
828 citations
TL;DR: A simple one-step hydrothermal method toward in situ growth of ultradispersed mesoporous TiO2 nanocrystals with (001) facets on GAs results in highly active photocatalysis, a high rate capability, and stable cycling.
Abstract: TiO2/graphene composites have been well studied as a solar light photocatalysts and electrode materials for lithium-ion batteries (LIBs). Recent reports have shown that ultralight 3D-graphene aerogels (GAs) can better adsorb organic pollutants and can provide multidimensional electron transport pathways, implying a significant potential application for photocatalysis and LIBs. Here, we report a simple one-step hydrothermal method toward in situ growth of ultradispersed mesoporous TiO2 nanocrystals with (001) facets on GAs. This method uses glucose as the dispersant and linker owing to its hierarchically porous structure and a high surface area. The TiO2/GAs reported here exhibit a highly recyclable photocatalytic activity for methyl orange pollutant and a high specific capacity in LIBs. The strong interaction between TiO2 and GAs, the facet characteristics, the high electrical conductivity, and the three-dimensional hierarchically porous structure of these composites results in highly active photocatalysi...
746 citations
TL;DR: In this paper, the mesoporous NiCo2O4 nanowire arrays (NWAs) are successfully fabricated by a simple surfactant-assisted hydrothermal method combined with a short post annealing treatment, which can be directly applied as self-supported electrodes for energy storage devices.
Abstract: Binary metal oxides has been regarded as a promising class of electrode materials for high-performance energy storage devices since it offers higher electrochemical activity and higher capacity than mono-metal oxide. Besides, rational design of electrode architectures is an effective solution to further enhance electrochemical performance of energy storage devices. Here, the advanced electrode architectures consisting of carbon textiles uniformally covered by mesoporous NiCo2O4 nanowire arrays (NWAs) are successfully fabricated by a simple surfactant-assisted hydrothermal method combined with a short post annealing treatment, which can be directly applied as self-supported electrodes for energy storage devices, such as Li-ion batteries, supercapacitors. The as-prepared mesoporous NiCo2O4 nanowires consist of numerous highly crystalline nanoparticles, leaving a large number of mesopores to alleviate the volume change during the charge/discharge process. Electrode architectures presented here promise fast electron transport by direct connection to the growth substrate and facile ion diffusion path provided by both the abundant mesoporous structure in nanowires and large open spaces between neighboring nanowires, which ensures every nanowire participates in the ultrafast electrochemical reaction. Benefiting from the intrinsic materials and architectures features, the unique binder-free NiCo2O4/carbon textiles exhibit high specific capacity/capacitance, excellent rate capability, and cycling stability.
709 citations
TL;DR: Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell.
Abstract: Hollow-structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft-templating and hard-templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented.
645 citations
TL;DR: The 3D-dendritic MSNSs show their unique advantage for protein loading and releasing due to their tunable large pore sizes and smart hierarchical mesostructures, and the releasing rates are partly dependent on the hierarchical biodegradation.
Abstract: A kind of novel uniform monodispersed three-dimensional dendritic mesoporous silica nanospheres (3D-dendritic MSNSs) has been successfully synthesized for the first time. The 3D-dendritic MSNSs can have hierarchical mesostructure with multigenerational, tunable center-radial, and dendritic mesopore channels. The synthesis was carried out in the heterogeneous oil–water biphase stratification reaction system, which allowed the self-assembly of reactants taking place in the oil–water interface for one-pot continuous interfacial growth. The average pore size of each generation for the 3D-dendritic MSNSs can be adjusted from 2.8 to 13 nm independently, which can be controlled by the varied hydrophobic solvents and concentration of silica source in the upper oil phase. The thickness of each generation can be tuned from ∼5 to 180 nm as desired, which can be controlled by the reaction time and amount of silica source. The biphase stratification approach can also be used to prepare other core–shell and functional ...
585 citations
TL;DR: The mechanical degradation on cycling can be deliberately controlled to finely tune mesoporous structure of the metal oxide sphere and optimize stable solid-electrolyte interface by high-rate lithiation-induced reactivation, which offers a new perspective in designing high-performance electrodes for long-lived lithium-ion batteries.
Abstract: Hollow structured materials are promising electrodes for energy storage, but still suffer from mechanical and chemical degradations in operation. Here, the authors show that upon high-rate lithiation reactivation, hierarchically mesoporous structures can be created to mitigate the degradations.
574 citations
TL;DR: The unique planar mesoporous shells of the NDCN provide exposed highly electroactive and stable catalytic sites, which boost the electrocatalytic activity of metal-free N DCN catalyst.
Abstract: Nitrogen-doped carbon nanosheets (NDCN) with size-defined mesopores are reported as highly efficient metal-free catalyst for the oxygen reduction reaction (ORR). A uniform and tunable mesoporous structure of NDCN is prepared using a templating approach. Such controlled mesoporous structure in the NDCN exerts an essential influence on the electrocatalytic performance in both alkaline and acidic media for the ORR. The NDCN catalyst with a pore diameter of 22 nm exhibits a more positive ORR onset potential than that of Pt/C (−0.01 V vs. −0.02 V) and a high diffusion-limited current approaching that of Pt/C (5.45 vs. 5.78 mA cm−2) in alkaline medium. Moreover, the catalyst shows pronounced electrocatalytic activity and long-term stability towards the ORR under acidic conditions. The unique planar mesoporous shells of the NDCN provide exposed highly electroactive and stable catalytic sites, which boost the electrocatalytic activity of metal-free NDCN catalyst.
544 citations
TL;DR: An ordered meso-microporous core-shell carbon (MMCS) as a sulfur container, which combines the advantages of both mesoporous and microporous carbon, is presented, demonstrating that the diffusion of the polysulfides into the bulk electrolyte can be greatly reduced.
Abstract: For lithium–sulfur batteries, commercial application is hindered by the insulating nature of sulfur and the dissolution of the reaction intermediates of polysulfides. Here, we present an ordered meso-microporous core–shell carbon (MMCS) as a sulfur container, which combines the advantages of both mesoporous and microporous carbon. With large pore volume and highly ordered porous structure, the “core” promises a sufficient sulfur loading and a high utilization of the active material, while the “shell” containing microporous carbon and smaller sulfur acts as a physical barrier and stabilizes the cycle capability of the entire S/C composite. Such a S/MMCS composite exhibits a capacity as high as 837 mAh g–1 at 0.5 C after 200 cycles with a capacity retention of 80% vs the second cycle (a decay of only 0.1% per cycle), demonstrating that the diffusion of the polysulfides into the bulk electrolyte can be greatly reduced. We believe that the tailored highly ordered meso-microporous core–shell structured carbon ...
534 citations
TL;DR: The large pores and small dimensions of the N-heteroatom-doped carbon spheres contribute to the mass transportation by reducing and smoothing the diffusion pathways, leading to high electrocatalytic activity.
Abstract: The synthesis of highly nitrogen-doped mesoporous carbon spheres (NMCS) is reported. The large pores of the NMCS were obtained through self-polymerization of dopamine (DA) and spontaneous co-assembly of diblock copolymer micelles. The resultant narrowly dispersed NMCS possess large mesopores (ca. 16 nm) and small particle sizes (ca. 200 nm). The large pores and small dimensions of the N-heteroatom-doped carbon spheres contribute to the mass transportation by reducing and smoothing the diffusion pathways, leading to high electrocatalytic activity.
TL;DR: The addition of alkali ions (sodium or potassium) to gold on KLTL-zeolite and mesoporous MCM-41 silica stabilizes mononuclear gold in Au-O(OH)x-(Na or K) ensembles and paves the way for using earth-abundant supports to disperse and stabilize precious metal atoms with alkali additives for the WGS and potentially other fuel-processing reactions.
Abstract: We report that the addition of alkali ions (sodium or potassium) to gold on KLTL-zeolite and mesoporous MCM-41 silica stabilizes mononuclear gold in Au-O(OH)x-(Na or K) ensembles. This single-site gold species is active for the low-temperature (<200°C) water-gas shift (WGS) reaction. Unexpectedly, gold is thus similar to platinum in creating -O linkages with more than eight alkali ions and establishing an active site on various supports. The intrinsic activity of the single-site gold species is the same on irreducible supports as on reducible ceria, iron oxide, and titania supports, apparently all sharing a common, similarly structured gold active site. This finding paves the way for using earth-abundant supports to disperse and stabilize precious metal atoms with alkali additives for the WGS and potentially other fuel-processing reactions.
TL;DR: This research has demonstrated that utilization of sustainable biopolymers as the raw materials for high performance supercapacitor electrode materials is an effective way to fabricate low-cost energy storage devices.
Abstract: Renewable, cost-effective and eco-friendly electrode materials have attracted much attention in the energy conversion and storage fields. Bagasse, the waste product from sugarcane that mainly contains cellulose derivatives, can be a promising candidate to manufacture supercapacitor electrode materials. This study demonstrates the fabrication and characterization of highly porous carbon aerogels by using bagasse as a raw material. Macro and mesoporous carbon was first prepared by carbonizing the freeze-dried bagasse aerogel; consequently, microporous structure was created on the walls of the mesoporous carbon by chemical activation. Interestingly, it was observed that the specific surface area, the pore size and distribution of the hierarchical porous carbon were affected by the activation temperature. In order to evaluate the ability of the hierarchical porous carbon towards the supercapacitor electrode performance, solid state symmetric supercapacitors were assembled, and a comparable high specific capacitance of 142.1 F g−1 at a discharge current density of 0.5 A g−1 was demonstrated. The fabricated solid state supercapacitor displayed excellent capacitance retention of 93.9% over 5000 cycles. The high energy storage ability of the hierarchical porous carbon was attributed to the specially designed pore structures, i.e., co-existence of the micropores and mesopores. This research has demonstrated that utilization of sustainable biopolymers as the raw materials for high performance supercapacitor electrode materials is an effective way to fabricate low-cost energy storage devices.
TL;DR: Non-siliceous mesoporous oxides are comprehensively described, including a discussion of constituting elements, synthesis, and structures, and general aspects concerning pore size control, atomic scale crystallinity, and phase control are reviewed.
Abstract: Mesoporous non-siliceous oxides have attracted great interest due to their unique properties and potential applications. Since the discovery of mesoporous silicates in 1990s, organic–inorganic assembly processes by using surfactants or block copolymers as soft templates have been considered as a feasible path for creating mesopores in metal oxides. However, the harsh sol–gel conditions and low thermal stabilities have limited the expansion of this method to various metal oxide species. Nanocasting, using ordered mesoporous silica or carbon as a hard template, has provided possibilities for preparing novel mesoporous materials with new structures, compositions and high thermal stabilities. This review concerns the synthesis, composition, and parameter control of mesoporous non-siliceous oxides. Four synthesis routes, i.e. soft-templating (surfactants or block copolymers as templates), hard-templating (mesoporous silicas or carbons as sacrificial templates), colloidal crystal templating (3-D ordered colloidal particles as a template), and super lattice routes, are summarized in this review. Mesoporous metal oxides with different compositions have different properties. Non-siliceous mesoporous oxides are comprehensively described, including a discussion of constituting elements, synthesis, and structures. General aspects concerning pore size control, atomic scale crystallinity, and phase control are also reviewed.
TL;DR: Graphene nanosheet-supported ultrafine metal nanoparticles encapsulated by thin mesoporous SiO2 layers were prepared and used as robust catalysts with high catalytic activity and excellent high-temperature stability, which can be recycled and reused in many gas- and solution-phase reactions.
Abstract: Graphene nanosheet-supported ultrafine metal nanoparticles encapsulated by thin mesoporous SiO2 layers were prepared and used as robust catalysts with high catalytic activity and excellent high-temperature stability. The catalysts can be recycled and reused in many gas- and solution-phase reactions, and their high catalytic activity can be fully recovered by high-temperature regeneration, should they be deactivated by feedstock poisoning. In addition to the large surface area provided by the graphene support, the enhanced catalytic performance is also attributed to the mesoporous SiO2 layers, which not only stabilize the ultrafine metal nanoparticles, but also prevent the aggregation of the graphene nanosheets. The synthetic strategy can be extended to other metals, such as Pd and Ru, for preparing robust catalysts for various reactions.
TL;DR: A cobalt-nitrogen-doped porous carbon that exhibits a ribbon-shape morphology, high surface area, mesoporous structure, and high nitrogen and cobalt content is fabricated for high-performance self-supported oxygen reduction electrocatalytsts through template-free pyrolysis of cobalt porphyrin-based conjugated mesoporus polymer frameworks.
Abstract: A cobalt-nitrogen-doped porous carbon that exhibits a ribbon-shape morphology, high surface area, mesoporous structure, and high nitrogen and cobalt content is fabricated for high-performance self-supported oxygen reduction electrocatalytsts through template-free pyrolysis of cobalt porphyrin-based conjugated mesoporous polymer frameworks.
TL;DR: In this article, the authors summarize the significant advances on the synthesis of mesoporous TiO2 in terms of rationally controlling the hydrolysis and condensation rates of titanium precursors to enable the cooperative assembly and/or successful infiltration via the templating methods.
Abstract: Mesoporous TiO2 has gained increasing interest because of its outstanding properties and promising applications in a wide range of fields. In this Perspective, we summarize the significant advances on the synthesis of mesoporous TiO2 in terms of rationally controlling the hydrolysis and condensation rates of titanium precursors to enable the cooperative assembly and/or successful infiltration via the templating methods. The rational designs and fundamentals for preparing mesoporous TiO2 are presented in the context of improving the conversion efficiencies of solar energy (e.g., maximizing the UV and/or visible light adsorption, minimizing the recombination of photogenerated electron–hole pairs, and optimizing the mass and charge transport) and enhancing the performances of lithium-ion batteries. New trends and ongoing challenges in this field are also highlighted and proposed.
TL;DR: The addition of Br in the perovskite structure was demonstrated to improve slightly the lifetime of the devices and the efficiencies of all devices tested remained at least at the 80% of the initial value 1 month after their preparation.
Abstract: We report on the preparation of a series of solution-processed perovskite solar cells based on methylammonium (MA) lead halide derivatives, MAPbX3, which show tunable optical properties depending on the nature and ratio of the halides employed (X = Cl, Br, and I). Devices have been prepared with different cell architecture, thin film, and mesoporous scaffold (TiO2 and Al2O3). We have analyzed different sample sets focusing on the characterization of the charge recombination by means of impedance spectroscopy (IS). On the one hand, our study discloses that the insertion of both Cl and Br in the perovskite lattice reduces the charge recombination rates in the light absorber film, thus determining the open circuit voltage (Voc) of the device. The samples prepared on a mesoporous Al2O3 electrode present lower charge recombination rates than those devices prepared on mesoporous TiO2. Furthermore, the addition of Br in the perovskite structure was demonstrated to improve slightly the lifetime of the devices; in fact, the efficiencies of all devices tested remained at least at the 80% of the initial value 1 month after their preparation. These results highlight the crucial role of the charge-recombination processes on the performance of the perovskite solar cells and pave the way for further progress on this field.
TL;DR: The meso-CuFe2O4 presented excellent catalytic activity for the degradation of imidacloprid, achieving almost complete removal of 10mg−L−1 imidcloprid after 5h at the reaction conditions of 0.3g−L −1 catalyst and 40mM H2O2.
Abstract: Highly ordered mesoporous copper ferrite (meso-CuFe2O4) with high surface area and large pore size was successfully fabricated and firstly proposed as a heterogeneous Fenton catalyst. It was synthesized through the nanocasting strategy by using KIT-6 as hard template. The morphology and physicochemical properties of meso-CuFe2O4 were characterized by SEM, TEM, XRD, XPS, FT-IR, Raman spectra, etc. The obtained results showed that the surface area and the pore size of meso-CuFe2O4 were 122 m2 g−1 and 9.2 nm, respectively. The meso-CuFe2O4 presented excellent catalytic activity for the degradation of imidacloprid, achieving almost complete removal of 10 mg L−1 imidacloprid after 5 h at the reaction conditions of 0.3 g L−1 catalyst and 40 mM H2O2. Kinetic analysis showed that the degradation of imidacloprid follows the pseudo-first order. The apparent rate constant for meso-CuFe2O4 was 1.0445 h−1, which was 1.5, 2 and 2.5 times than those of meso-CoFe2O4, con-CuFe2O4 and nano-Fe3O4, respectively. The amount of hydroxyl radical (OH) generated was directly proportional to the degradation efficiency of imidacloprid, suggesting the involvement of OH in oxidizing imidacloprid. The obtained results indicated that meso-CuFe2O4 presented the highest activity, which was not only due to its ordered mesoporous structure with high surface area and large pore size, but also assigned to the redox recycle of Fe2+/Fe3+ and Cu+/Cu2+ in meso-CuFe2O4. The special effect of Cu was discussed in terms of the thermodynamically favorable Fe3+ reduction by Cu+, regenerating the active species Fe2+. The meso-CuFe2O4 presented very low iron leaching (<1 ppm) even in acidic condition and retained almost its high catalytic activity after 5 consecutive runs. Besides, meso-CuFe2O4 possessed medium saturation magnetization, which had provided a potential advantage for the recovery and reuse of catalyst.
TL;DR: In this paper, a mesoporous ZnS shell is grown on a CdS core through a one-pot surfactant-free hydrothermal route, and the shell exhibits excellent photocatalytic stability over 60 h.
Abstract: A mesoporous ZnS shell is in situ grown on a CdS core through a one-pot surfactant-free hydrothermal route. Due to the mesoporous ZnS shell and the unique spatial distribution of the photoexcited charge carriers in the CdS–ZnS core–shell particles, the hydrogen evolution rate over CdS–ZnS is 169 and 56 times higher than that of ZnS and CdS under visible light, respectively. Moreover, the core–shell particles show excellent photocatalytic stability over 60 h.
TL;DR: In this article, a hierarchical mesoporous NiCo2O4@MnO2 core-shell nanowire arrays on nickel foam via a facile hydrothermal and electrodeposition process for supercapacitor applications were demonstrated.
Abstract: We demonstrate the design and fabrication of hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam via a facile hydrothermal and electrodeposition process for supercapacitor applications. In order to increase the energy density and voltage window, a high-voltage asymmetric supercapacitor based on hierarchical mesoporous NiCo2O4@MnO2 core–shell nanowire arrays on nickel foam as the positive electrode and activated carbon (AC) as the negative electrode was successfully fabricated. The as-fabricated asymmetric supercapacitor device achieved a specific capacitance of 112 F g−1 at a current density of 1 mA cm−2 with a stable operational voltage of 1.5 V and a maximum energy density of 35 W h kg−1. The present NiCo2O4@MnO2 core–shell nanowire arrays with remarkable electrochemical properties could be considered as potential electrode materials for next generation supercapacitors in high energy density storage systems.
TL;DR: In this paper, the authors reported non-templated synthesis of interconnected microporous carbon (IMPC) sheets having beehive morphology by direct pyrolysis of poly(acrylamide-co-acrylic acid) potassium salt in inert atmosphere without any activation.
Abstract: We report non-templated synthesis of interconnected microporous carbon (IMPC) sheets having beehive morphology by direct pyrolysis of poly(acrylamide-co-acrylic acid) potassium salt in inert atmosphere without any activation. The presence of the alkali metal in the selected polymer precursor results in a high specific surface area of 1327 m2 g−1. Importantly, 80% of the pore volume is contributed by micropores with pore size ranging from 1–2 nm which is ideal for use as an electrode for supercapacitors. Whereas the rest of the surface area was contributed by a small fraction of mesopores and macropores due to the interconnected structure. The presence of three different types of pores make the material ideal for supercapacitor electrodes. IMPC was tested as an electrode in both aqueous and non-aqueous supercapacitors. All the aqueous measurements were done in 1 M H2SO4 solution with a potential window 1 V. A specific capacitance of 258 F g−1 was realized at a constant charge–discharge current of 0.5 A g−1 and it maintained at a value of 150 F g−1 at 30 A g−1. A long cycle stability of 90% capacitance retention was observed after 5000 charge–discharge cycles at a current density of 2 A g−1. At the highest power density 13 600 W kg−1 the energy density was found to be 3.1 W h kg−1. Non aqueous performance was tested in the presence of 1 M LiPF6 in ethylene carbonate–di-methyl carbonate with 5 mg active material loading. A specific capacitance of 138 F g−1 was obtained at a current density of 0.25 A g−1 and it retained at a value of 100 F g−1 at 10 A g−1. The material can deliver an energy density of 31 W h kg−1 at its highest power density of 11 000 W kg−1 in a two electrode system based on active material loading.
TL;DR: The dual-compartment Janus mesoporous silica nanocomposites can be further applied into nanobiomedicine for heat and NIR light bimodal-triggered dual-drugs controllable release and realizes significantly higher efficiency for cancer cell killing compared to that of the single- Triggered drugs delivery system.
Abstract: Multifunctional dual-compartment Janus mesoporous silica nanocomposites of UCNP@SiO2@mSiO2&PMO (UCNP = upconversion nanoparticle, PMO = periodic mesoporous organosilica) containing core@shell@shell structured UCNP@SiO2@mSiO2 nanospheres and PMO single-crystal nanocubes have been successfully synthesized via a novel anisotropic island nucleation and growth approach with the ordered mesostructure. The asymmetric Janus nanocomposites show a very uniform size of ~300 nm and high surface area of ~1290 m(2)/g. Most importantly, the Janus nanocomposites possess the unique dual independent mesopores with different pore sizes (2.1 nm and 3.5-5.5 nm) and hydrophobicity/hydrophilicity for loading of multiple guests. The distinct chemical properties of the silica sources and the different mesostructures of the dual-compartments are the necessary prerequisites for the formation of the Janus nanostructure. With the assistance of the near-infrared (NIR) to ultraviolet/visible (UV-vis) optical properties of UCNPs and heat-sensitive phase change materials, the dual-compartment Janus mesoporous silica nanocomposites can be further applied into nanobiomedicine for heat and NIR light bimodal-triggered dual-drugs controllable release. It realizes significantly higher efficiency for cancer cell killing (more than 50%) compared to that of the single-triggered drugs delivery system (~25%).
TL;DR: This work synthesized mesoporous carbon from pre-cross-linked lignin gel impregnated with a surfactant as the pore-forming agent and activated the carbon through physical and chemical methods to obtain activated mesoporus carbon.
Abstract: We synthesized mesoporous carbon from pre-cross-linked lignin gel impregnated with a surfactant as the pore-forming agent and then activated the carbon through physical and chemical methods to obtain activated mesoporous carbon. The activated mesoporous carbons exhibited 1.5- to 6-fold increases in porosity with a maximum Brunauer–Emmett–Teller (BET) specific surface area of 1148 m2/g and a pore volume of 1.0 cm3/g. Both physical and chemical activation enhanced the mesoporosity along with significant microporosity. Plots of cyclic voltammetric data with the capacitor electrode made from these carbons showed an almost rectangular curve depicting the behavior of ideal double-layer capacitance. Although the pristine mesoporous carbon exhibited a range of surface-area-based capacitance similar to that of other known carbon-based supercapacitors, activation decreased the surface-area-based specific capacitance and enhanced the gravimetric specific capacitance of the mesoporous carbons. A vertical tail in the ...
TL;DR: A novel COF, which bears two different kinds of ordered pores with controllable sizes: one within microporous range and the other in mesoporous range, has been constructed via one-step synthesis.
Abstract: Covalent organic frameworks (COFs) are crystalline porous materials bearing microporous or mesoporous pores. The type and size of pores play crucial roles in regulating the properties of COFs. In this work, a novel COF, which bears two different kinds of ordered pores with controllable sizes: one within microporous range (7.1 A) and the other in mesoporous range (26.9 A), has been constructed via one-step synthesis. The structure of the dual-pore COF was confirmed by PXRD investigation, nitrogen adsorption–desorption study, and theoretical calculations.
TL;DR: This work presents the synthesis of a shape-persistent cage compound by the reversible formation of 24 boronic ester units of 12 triptycene tetraol molecules and 8 triboronic acid molecules, which is a mesoporous material with a very high specific surface area.
Abstract: Recently, porous organic cage crystals have become a real alternative to extended framework materials with high specific surface areas in the desolvated state. Although major progress in this area has been made, the resulting porous compounds are restricted to the microporous regime, owing to the relatively small molecular sizes of the cages, or the collapse of larger structures upon desolvation. Herein, we present the synthesis of a shape-persistent cage compound by the reversible formation of 24 boronic ester units of 12 triptycene tetraol molecules and 8 triboronic acid molecules. The cage compound bears a cavity of a minimum inner diameter of 2.6 nm and a maximum inner diameter of 3.1 nm, as determined by single-crystal X-ray analysis. The porous molecular crystals could be activated for gas sorption by removing enclathrated solvent molecules, resulting in a mesoporous material with a very high specific surface area of 3758 m2 g−1 and a pore diameter of 2.3 nm, as measured by nitrogen gas sorption.
TL;DR: In this article, the mesoporous adsorbent was successfully prepared by 6-((2-hydroxy-1-naphthoyl)hydrazono)methyl)benzoic acid (HMBA) embedded onto mesophorous silica monoliths.
TL;DR: In this article, a mesoporous nitrogen-doped carbon prepared from (1-methyl-1H-pyrrole-2-yl)methanol in the presence of a meso-SiO2 template (KIT-6) is presented.
Abstract: Electrochemical reduction of oxygen molecules can produce H2O2, which is an important chemical for a green and sustainable society; therefore, the development of catalysts for this reaction is necessary. We propose mesoporous nitrogen-doped carbon prepared from (1-methyl-1H-pyrrole-2-yl)methanol in the presence of a mesoporous SiO2 template (KIT-6). The nitrogen content of the resulting carbon can be controlled in the range of 0–10 at. % and all prepared samples have well-ordered mesopores with diameters of 3.4–4.0 nm. Electrochemical studies indicate the present materials have high catalytic activities with high selectivity toward H2O2 over 90%. Such high selectivity toward H2O2 is probably due to good mass transport in the catalyst layer, which is enhanced by the mesoporous structure.
TL;DR: PCN-600(Fe) has been demonstrated as an effective peroxidase mimic to catalyze the co-oxidation reaction and is to the authors' knowledge the only mesoporous porphyrinic MOF stable under basic aqueous conditions.
Abstract: A series of mesoporous metalloporphyrin Fe-MOFs, namely PCN-600(M) (M = Mn, Fe, Co, Ni, Cu), have been synthesized using the preassembled [Fe3O(OOCCH3)6] building block. PCN-600 exhibits a one-dimensional channel as large as 3.1 nm and the highest experimental pore volume of 1.80 cm3g–1 among all the reported porphyrinic MOFs. It also shows very high stability in aqueous solutions with pH values ranging from 2–11 and is to our knowledge the only mesoporous porphyrinic MOF stable under basic aqueous conditions. PCN-600(Fe) has been demonstrated as an effective peroxidase mimic to catalyze the co-oxidation reaction.
TL;DR: In this article, a 3D ordered mesoporous Ag/Co3O4 and K-Ag/Co 3O4 catalysts were successfully prepared on the basis of 3D-Co3 O4.
Abstract: Three-dimensional (3D) ordered mesoporous Ag/Co3O4 and K–Ag/Co3O4 catalysts were successfully prepared on the basis of 3D-Co3O4. All catalysts possess 3D mesoporous structures, which are not affected due to Ag and K addition. Ag nanoparticles, uniformly dispersed and supported on the polycrystalline wall of K–Ag/Co3O4, provide sufficient active sites for HCHO oxidation reaction. 1.7% K–Ag/Co3O4 has turnover frequencies (TOFs) of 0.22 s–1 at 60 °C and 2.62 s–1 at 100 °C, and its HCHO conversion at room temperature is 55% (HCHO 100 ppm and GHSV 30000 h–1). The addition of K+ ions obviously promotes the catalytic performance for HCHO oxidation due to surface OH– species provided by K+ ions and more abundant Ag(111) active faces, Co3+ cations and surface lattice oxygen (O2–) species generated by stronger interaction between Ag and Co and anion lattice defects. Ag(111) faces, Co3+ ions, and O2– are active species. Combined with TOFs, at low temperature (<80 °C), the HCHO catalytic activity on K–Ag/Co3O4 cataly...