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Mietek Jaroniec - One of the best experts on this subject based on the ideXlab platform.

  • Soft Templating synthesis of n doped mesoporous carbon nanospheres for enhanced oxygen reduction reaction
    Chemistry-an Asian Journal, 2015
    Co-Authors: Bita Bayatsarmadi, Mietek Jaroniec, Yao Zheng, Shizhang Qiao
    Abstract:

    The development of ordered mesoporous carbon materials with controllable structures and improved physicochemical properties by doping heteroatoms such as nitrogen into the carbon framework has attracted a lot of attention, especially in relation to energy storage and conversion. Herein, a series of nitrogen-doped mesoporous carbon spheres (NMCs) was synthesized via a facile dual Soft-Templating procedure by tuning the nitrogen content and carbonization temperature. Various physical and (electro)chemical properties of the NMCs have been comprehensively investigated to pave the way for a feasible design of nitrogen-containing porous carbon materials. The optimized sample showed a favorable electrocatalytic activity as evidenced by a high kinetic current and positive onset potential for oxygen reduction reaction (ORR) due to its large surface area, high pore volume, good conductivity, and high nitrogen content, which make it a highly efficient ORR metal-free catalyst in alkaline solutions.

  • organic acid assisted Soft Templating synthesis of ordered mesoporous carbons
    Adsorption-journal of The International Adsorption Society, 2013
    Co-Authors: J Choma, Katarzyna Jedynak, Michal Marszewski, Mietek Jaroniec
    Abstract:

    A series of Soft-templated ordered mesoporous carbons (OMCs) was synthesized by using resorcinol and formaldehyde as carbon precursors, triblock copolymer Pluronic F127 as a Soft-template, and an organic acid (acetic, benzoic, citric, oxalic, or succinic) as a polymerization reaction catalyst. The aforementioned organic acids were strong enough to facilitate the formation of ordered mesophases by the block copolymer template used and to catalyze the polymerization reaction of resorcinol and formaldehyde in this template. The use of weak organic acids instead of strong inorganic acids such as HCl eliminated inorganic anions from the reaction environment and resulted in high surface area OMCs. Basically, the resulting carbons showed the surface areas and pore volumes comparable to those reported for the carbons prepared under similar conditions but in the presence of strong inorganic acids. Electron microscopy analysis proved the presence of ordered mesopores, whereas thermogravimetric analysis showed a good thermal stability of these carbons.

  • Soft Templating synthesis of ordered mesoporous carbons in the presence of tetraethyl orthosilicate and silver salt
    Microporous and Mesoporous Materials, 2012
    Co-Authors: Laura Sterk, Joanna Gorka, Ajayan Vinu, Mietek Jaroniec
    Abstract:

    Soft-Templating synthesis of ordered mesoporous carbons (OMCs) in the presence of tetraethyl orthosilicate (TEOS) and silver nitrate was carried out in order to introduce silver nanoparticles and to create additional microporosity in these materials. This strategy was employed to obtain the phenolic resin-based OMCs with two different loadings of silver. Also, this approach was used to obtain silver-containing mesoporous carbon–silica hybrids, which after dissolving silica with NaOH solution gave microporous–mesoporous carbons with Ag particles. Nitrogen adsorption, small and wide angle X-ray diffraction, transmission electron microscopy and thermogravimetric analysis showed good adsorption and structural properties of the aforementioned OMC materials.

  • Soft Templating synthesis and adsorption properties of mesoporous carbons with embedded silver nanoparticles
    Adsorption-journal of The International Adsorption Society, 2011
    Co-Authors: J Choma, Joanna Gorka, Katarzyna Jedynak, Mietek Jaroniec
    Abstract:

    Mesoporous carbons containing silver nanoparticles have been successfully synthesized under acidic conditions by employing resorcinol and formaldehyde as carbon precursors and triblock copolymer EO101PO56EO101 (Lutrol F127) as a Soft template. Silver nanoparticles of ∼90 nm were added to the synthesis mixture to achieve 10 wt% and 20 wt% of Ag loading in the carbon. Also, tetraethyl orthosilicate (TEOS) was introduced to the system in order to improve adsorption properties of the silver-carbon composites and to reinforce its structure. The resulting carbons with incorporated silver nanoparticles featured high surface areas, large total pore volumes and primary mesopores in the range between ∼6–7 nm.

  • tailoring adsorption and framework properties of mesoporous polymeric composites and carbons by addition of organosilanes during Soft Templating synthesis
    Journal of Physical Chemistry C, 2010
    Co-Authors: Joanna Gorka, Mietek Jaroniec
    Abstract:

    A series of Soft-templated mesoporous polymeric composites and carbons was synthesized under acidic conditions by using resorcinol and formaldehyde in the presence of organosilanes such as tetraethyl orthosilicate and tris(3-trimethoxysilylpropyl)isocyanurate. Poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide) triblock copolymer, Pluronic F127, was employed as a Soft template. While the self-assembly of resorcinol, formaldehyde, and block copolymer combined with polymerization and proper thermal treatment affords mesoporous polymers and carbons with high surface area, large pore volume, and well-developed mesoporosity, the addition of organosilanes into this process opens new possibilities for tailoring adsorption, surface, and framework properties of these materials and for expanding their porosity. It is shown that the use of heterocyclic organosilanes in the aforementioned Soft-Templating synthesis affords heteroatom-doped mesoporous carbons, the properties of which can be further modified...

Yusuke Yamauchi - One of the best experts on this subject based on the ideXlab platform.

  • Mesoporous gold nanospheres: Via thiolate-Au(I) intermediates
    Chemical Science, 2019
    Co-Authors: Hao Lv, Aaron Lopes, Dongdong Xu, Joel Henzie, Ji Feng, Yusuke Yamauchi
    Abstract:

    Mesoporous gold (mesoAu) nanospheres support enhanced (electro)catalytic performance owing to their three-dimensional (3D) interior mesochannels that expose abundant active sites and facilitate electron/mass transfers. Although various porous Nanostructured Au has been fabricated by electrochemical reduction, alloying–dealloying and hard/Soft Templating methods, successful synthesis of mesoAu nanospheres with tailorable sizes and porosities remains a big challenge. Here we describe a novel surfactant-directed synthetic route to fabricate mesoAu nanospheres with 3D interconnected mesochannels by using the amphiphilic surfactant of C22H45N+(CH3)2–C3H6–SH (Cl−) (C22N–SH) as the mesopore directing agent. C22N–SH can not only self-reduce trivalent Au(III)Cl4− to monovalent Au(I), but also form polymeric C22N–S–Au(I) intermediates via covalent bonds. These C22N–S–Au(I) intermediates facilitate the self-assembly into spherical micelles and inhibit the mobility of Au precursors, enabling the crystallization nucleation and growth of the mesoAu nanospheres via in situ chemical reduction. The synthetic strategy can be further extended to tailor the sizes/porosities and surface optical properties of the mesoAu nanospheres. The mesoAu nanospheres exhibit remarkably enhanced mass/specific activity and improved stability in methanol electrooxidation, demonstrating far better performance than non-porous Au nanoparticles and previously reported Au nanocatalysts. The synthetic route differs markedly from other long-established Soft-Templating approaches, providing a new avenue to grow metal nanocrystals with desirable nanostructures and functions.

  • fabrication of nanoporous carbon materials with hard and Soft Templating approaches a review
    Journal of Nanoscience and Nanotechnology, 2019
    Co-Authors: Victor Malgras, Katsuhiko Ariga, Jing Tang, Jie Wang, Jeonghun Kim, Nagy L Torad, Saikat Dutta, Shahriar A Hossain, Yusuke Yamauchi
    Abstract:

    Hard- and Soft-Templating approaches are one of potential strategies for the fabrication of functional nanoporous carbon materials with desired morphologies and properties. Enormous efforts have been paid for understanding the synthetic mechanisms that strongly influence the materials design and applications. All of these investigations are crucial to encourage the application of hard- and Soft-Templating approaches for the precise synthesis of nanoporous carbon materials. In this review, we mainly summarize significant works employing different synthetic methods for making carbon materials with various pore sizes and functionalities. The content of the review article contains: (i) Hard-Templating synthesis of microporous carbon from zeolites; (ii) Hard-Templating synthesis of mesoporous carbon from mesoporous silica; (iii) Hard-Templating synthesis of macroporous carbon; and (iv) Soft-Templating synthesis of mesoporous carbon. This review aims to provide a detailed glimpse of hard- and Soft-Templating approaches for future development of functional nanoporous carbon materials.

  • mesoporous bimetallic rhcu alloy nanospheres using a sophisticated Soft Templating strategy
    Chemistry of Materials, 2018
    Co-Authors: Bo Jiang, Joel Henzie, Kenya Kani, Muhammad Iqbal, Hideki Abe, Tatsuo Kimura, Md Shahriar A Hossain, Oruganti Anjaneyulu, Yusuke Yamauchi
    Abstract:

    Mesoporous metals are useful for heterogeneous catalysis because their ultrapermeable architecture promotes mass transport to abundant active sites. Our group recently developed a method to manipulate the interior space of nanocrystals by synthesizing mesoporous Rh nanospheres that serve as high performance catalysts for methanol oxidation and nitric oxide (NO) remediation (Jiang, B.; et al. Nat. Commun. 2017, 8, 15581). Here, we extend this concept and propose a sophisticated Soft-Templating strategy to synthesize three-dimensional mesoporous bimetallic RhCu nanospheres. The nanospheres are alloys of Rh and Cu, and their compositions can be continuously tuned by varying the amount of metal precursors. The mesoporous RhCu nanospheres were examined for catalytic remediation of NO and show good catalytic performance considering the reduced economic cost of the alloyed material. This method offers a general approach for the precise design of high surface area Rh-based metal catalysts.

  • first synthesis of continuous mesoporous copper films with uniformly sized pores by electrochemical Soft Templating
    Angewandte Chemie, 2016
    Co-Authors: Bo Jiang, Joel Henzie, Md Shahriar A Hossain, Zhongli Wang, Jung Ho Kim, Toshiaki Takei, Omer Dag, Yoshio Bando, Yusuke Yamauchi
    Abstract:

    Although mesoporous metals have been synthesized by electrochemical methods, the possible compositions have been limited to noble metals (e.g., palladium, platinum, gold) and their alloys. Herein we describe the first fabrication of continuously mesoporous Cu films using polymeric micelles as Soft templates to control the growth of Cu under sophisticated electrochemical conditions. Uniformly sized mesopores are evenly distributed over the entire film, and the pore walls are composed of highly crystalized Cu.

  • smart Soft Templating synthesis of hollow mesoporous bioactive glass spheres
    Chemistry: A European Journal, 2015
    Co-Authors: Bishnu Prasad Bastakoti, Yusuke Yamauchi
    Abstract:

    Hollow bioactive glass spheres with mesoporous shells were prepared by using dual Soft templates, a diblock co-polymer poly(styrene-b-acrylic acid) (PS-b-PAA) and a cationic surfactant cetyltrimethylammonium bromide (CTAB). Hollow mesoporous bioactive glass (HMBG) spheres comprise the large hollow interior with vertical mesochannels in shell, which realize large uptake of drugs and their sustained release. The formation of hydroxyapatite layer on the surface of HMBG particles shows the clear evidence for promising application in bone regeneration.

Tatsumi Ishihara - One of the best experts on this subject based on the ideXlab platform.

  • direct Soft Templating route to crystalline mesoporous transition metal oxides
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014
    Co-Authors: Limin Guo, Shintaro Ida, Hidehisa Hagiwara, Takeshi Daio, Tatsumi Ishihara
    Abstract:

    A direct and general Soft-Templating method has been developed to prepare crystalline mesoporous transition metal oxides. The method was versatile and simple. Several crystalline mesoporous transition metal oxides have been successfully synthesized, such as Nb2O5, Ta2O5 and α-Fe2O3. The porous structure, and crystallinity of as-synthesized metal oxides were characterized by XRD, TG-DTA, SEM, TEM and N2 sorption techniques. The crystallization of amorphous metal oxides resulted in the decrease of specific surface area due to the condensation of related amorphous metal oxide species and crystallite growth. At the same time, the pore volume was well maintained, which means the limited volume shrinkage. The pore size increased with the increasing of calcination temperature due to the growth of grain size and small pores emerged into larger ones. The as-synthesized metal oxides not only had clear mesostructure but also high crystallinity. Notably, all the reagents were commercial available and used without any treatment. It can be easily reproduced by researchers even without any experience in sol–gel related synthesis.

  • Soft Templating method to synthesize crystalline mesoporous α fe2o3 films
    New Journal of Chemistry, 2014
    Co-Authors: Limin Guo, Shintaro Ida, Takeshi Daio, Akihide Takashiba, Norio Teramae, Tatsumi Ishihara
    Abstract:

    Crystalline mesoporous α-Fe2O3 films were successfully synthesized using lab-synthesized di-block amphiphilic polymer poly(ethylene oxide)-b-poly(butyl acrylate) (PEO-b-PtBA) as a mesoporous structure directing agent and the film thickness can be adjusted by repeated spin-coatings.

Steven L Suib - One of the best experts on this subject based on the ideXlab platform.

  • magnetic studies of mesoporous nanostructured iron oxide materials synthesized by one step Soft Templating
    Dalton Transactions, 2015
    Co-Authors: Jing Jin, W A Hines, Chunghao Kuo, David M Perry, Altug S Poyraz, Yan Xia, Taha Zaidi, Muping Nieh, Steven L Suib
    Abstract:

    A combined magnetization and 57Fe spin-echo nuclear magnetic resonance (NMR) study has been carried out on mesoporous nanostructured materials consisting of the magnetite (Fe3O4) and maghemite (γ-Fe2O3) phases. Two series of samples were synthesized using a recently developed one-step Soft-Templating approach with systematic variations in calcination temperature and reaction atmosphere. Nuclear magnetic resonance has been shown to be a valuable tool for distinguishing between the two magnetic iron oxide spinel phases, Fe3O4 and γ-Fe2O3, on the nanoscale as well as monitoring phase transformation resulting from oxidation. For the Fe3O4 and γ-Fe2O3 phases, peaks in the NMR spectra are attributed to Fe in the tetrahedral (A) sites and octahedral (B) sites. The magnetic field dependence of the peaks was observed and confirmed the site assignments. Fe3O4 on a nanoscale readily oxidizes to form γ-Fe2O3 and this was clearly evident in the NMR spectra. As evidenced by transmission electron microscope (TEM) images, the porous mesostructure for the iron oxide materials is formed by a random close-packed aggregation of nanoparticles; correspondingly, superparamagnetic behavior was observed in the magnetic measurements. Although X-ray diffraction (XRD) shows the spinel structure for the Fe3O4 and γ-Fe2O3 phases, unlike NMR, it is difficult to distinguish between the two phases with XRD. Nitrogen sorption isotherms characterize the mesoporous structures of the materials, and yield BET surface area values and limited BJH pore size distribution curves.

  • mesoporous co3o4 nanostructured material synthesized by one step Soft Templating a magnetic study
    Journal of Applied Physics, 2014
    Co-Authors: Altug S Poyraz, W A Hines, Chunghao Kuo, David M Perry, Steven L Suib
    Abstract:

    A combined magnetization and zero-field 59Co spin-echo nuclear magnetic resonance (NMR) study has been carried out on one member of a recently developed class of highly ordered mesoporous nanostructured materials, mesoporous Co3O4 (designated UCT-8, University of Connecticut, mesoporous materials). The material was synthesized using one-step Soft-Templating by an inverse micelles packing approach. Characterization of UCT-8 by powder x-ray diffraction and electron microscopy reveals that the mesostructure consists of random close-packed Co3O4 nanoparticles ≈ 12 nm in diameter. The N2 sorption isotherm for UCT-8, which is type IV with a type H1 hysteresis loop, yields a 134 m2/g BET surface area and a 7.7 nm BJH desorption pore diameter. The effect of heat treatment on the structure is discussed. The antiferromagnetic Co3O4 nanoparticles have a Neel temperature TN = 27 K, somewhat lower than the bulk. A fit to the Curie-Weiss law over the temperature range 75 K ≤ T ≤ 300 K yields an effective magnetic moment of μeff = 4.36 μB for the Co2+ ions, indicative of some orbital contribution, and a Curie-Weiss temperature Θ = −93.5 K, consistent with antiferromagnetic ordering. The inter-sublattice and intra-sublattice exchange constants for the Co2+ ions are J1/kB = (−)4.75 K and J2/kB = (−)0.87 K, respectively, both corresponding to antiferromagnetic coupling. The presence of uncompensated surface spins is observed below TN with shifts in the hysteresis loops, i.e., an exchange-bias effect. The 59Co NMR spectrum for UCT-8, which is attributed to Co2+ ions at the tetrahedral A sites, is asymmetrically broadened with a peak at ≈55 MHz (T = 4.2 K). Since there is cubic symmetry at the A-sites, the broadening is indicative of a magnetic field distribution due to the uncompensated surface spins. The spectrum is consistent with antiferromagnetically ordered particles that are nanometer in size and single domain.

Joanna Gorka - One of the best experts on this subject based on the ideXlab platform.

  • Soft Templating synthesis of ordered mesoporous carbons in the presence of tetraethyl orthosilicate and silver salt
    Microporous and Mesoporous Materials, 2012
    Co-Authors: Laura Sterk, Joanna Gorka, Ajayan Vinu, Mietek Jaroniec
    Abstract:

    Soft-Templating synthesis of ordered mesoporous carbons (OMCs) in the presence of tetraethyl orthosilicate (TEOS) and silver nitrate was carried out in order to introduce silver nanoparticles and to create additional microporosity in these materials. This strategy was employed to obtain the phenolic resin-based OMCs with two different loadings of silver. Also, this approach was used to obtain silver-containing mesoporous carbon–silica hybrids, which after dissolving silica with NaOH solution gave microporous–mesoporous carbons with Ag particles. Nitrogen adsorption, small and wide angle X-ray diffraction, transmission electron microscopy and thermogravimetric analysis showed good adsorption and structural properties of the aforementioned OMC materials.

  • Soft Templating synthesis and adsorption properties of mesoporous carbons with embedded silver nanoparticles
    Adsorption-journal of The International Adsorption Society, 2011
    Co-Authors: J Choma, Joanna Gorka, Katarzyna Jedynak, Mietek Jaroniec
    Abstract:

    Mesoporous carbons containing silver nanoparticles have been successfully synthesized under acidic conditions by employing resorcinol and formaldehyde as carbon precursors and triblock copolymer EO101PO56EO101 (Lutrol F127) as a Soft template. Silver nanoparticles of ∼90 nm were added to the synthesis mixture to achieve 10 wt% and 20 wt% of Ag loading in the carbon. Also, tetraethyl orthosilicate (TEOS) was introduced to the system in order to improve adsorption properties of the silver-carbon composites and to reinforce its structure. The resulting carbons with incorporated silver nanoparticles featured high surface areas, large total pore volumes and primary mesopores in the range between ∼6–7 nm.

  • tailoring adsorption and framework properties of mesoporous polymeric composites and carbons by addition of organosilanes during Soft Templating synthesis
    Journal of Physical Chemistry C, 2010
    Co-Authors: Joanna Gorka, Mietek Jaroniec
    Abstract:

    A series of Soft-templated mesoporous polymeric composites and carbons was synthesized under acidic conditions by using resorcinol and formaldehyde in the presence of organosilanes such as tetraethyl orthosilicate and tris(3-trimethoxysilylpropyl)isocyanurate. Poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide) triblock copolymer, Pluronic F127, was employed as a Soft template. While the self-assembly of resorcinol, formaldehyde, and block copolymer combined with polymerization and proper thermal treatment affords mesoporous polymers and carbons with high surface area, large pore volume, and well-developed mesoporosity, the addition of organosilanes into this process opens new possibilities for tailoring adsorption, surface, and framework properties of these materials and for expanding their porosity. It is shown that the use of heterocyclic organosilanes in the aforementioned Soft-Templating synthesis affords heteroatom-doped mesoporous carbons, the properties of which can be further modified...

  • Soft Templating synthesis of nanoporous carbons with incorporated alumina nanoparticles
    Annales Umcs Chemistry, 2009
    Co-Authors: J Choma, Joanna Gorka, A żubrowska, Mietek Jaroniec
    Abstract:

    Soft-templated microporous-mesoporous carbons with embedded alumina nanoparticles were synthesized using resorcinol and formaldehyde as carbon precursors, different inorganic acids as a catalyst and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer as a Soft template. The carbons studied have very good adsorption properties such as high specific surface area, uniform pore size distribution and a large total pore volume. The choice of catalyst seems to play an important role for the incorporation of aluminum species to the carbon framework, which after thermal treatment form aluminum oxide nanoparticles. This simple approach seems to be very promising for the design of carbon-based materials for a broad range of applications.

  • incorporation of inorganic nanoparticles into mesoporous carbons synthesized by Soft Templating
    Journal of Physical Chemistry C, 2008
    Co-Authors: Joanna Gorka, Mietek Jaroniec
    Abstract:

    Mesoporous carbon monoliths with embedded alumina and silica nanoparticles were synthesized using phloroglucinol and formaldehyde as carbon precursors and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer as a Soft template. While the carbon mesostructure was not significantly affected by embedding silica nanoparticles (∼20 nm), this was not the case for the incorporation of alumina nanoparticles (∼50 nm). In the latter case a gradual reduction in the carbon mesoporosity was observed with increasing loading of alumina nanoparticles. Since various inorganic nanoparticles of different sizes and shapes are available commercially, the Soft-Templating synthesis route is a very promising way for the design of carbon-based materials with embedded nanoparticles of desired properties.