Formation and Applications of Hierarchically Porous Carbon, Metals and Metal Oxides Formed by Nanocasting

2012 ◽  
Vol 1389 ◽  
Author(s):  
Franchessa M. Sayler ◽  
Amy J. Grano ◽  
William Scogin ◽  
Pasha Sanders ◽  
Jan-Henrik Smått ◽  
...  
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Porous Carbon ◽  
Porous Silica ◽  
Ionic Conductors ◽  
Hierarchically Porous ◽  
Surface Areas ◽  
Wide Range ◽  
Hierarchically Porous Materials ◽  
Silica Template

ABSTRACTHierarchically porous materials are of interest in a wide range of applications. If the materials are electronic or ionic conductors such materials are of interest as electrodes for use in fuel cells, flow batteries, electrocatalysis, and pseudo/supercapacitors. We have demonstrated the synthesis of hierarchically porous carbon, metal and metal oxide monoliths. Hierarchically porous silica with porosity at three length scales: 0.5-30 micrometer, 200-500 nm, and 3-8 nm, is used as a template to form these materials. The porosity of the silica template is produced by spinodal decomposition (0.5-30 micrometer), particle agglomeration (200-500 nm) and addition of surfactant or block copolymer (3-8 nm). Nanocasting: replication of all or part of the structure via one of a number of chemical replication techniques has been used to produce the carbon, metal oxide and metal replicas. The final surface areas of the materials can be as high as 1200 m2/g for carbon replicas, and >300 m2/g for metals and metal oxides. The use of the nanocasting technique allows for formation of materials that are compositionally or spatially heterogeneous.We report here results on the synthesis and characterization of hierarchically porous monoliths of carbon and, nickel and the use of some of these monoliths in catalysis and electrochemical capacitors.

X-ray and FIB Tomography of Extremely High Surface Area Nanostructured Hollow Fiber Membranes

2012 ◽  
Vol 1421 ◽  
Author(s):  
Amy J. Grano ◽  
Franchessa M. Sayler ◽  
Amber Genau ◽  
Keana L. Graves ◽  
Brian M. Patterson ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Porous Silica ◽  
Porous Metal ◽  
Sample Volume ◽  
Ionic Conductors ◽  
Hierarchically Porous ◽  
X Ray ◽  
Synthesis Conditions ◽  
Wide Range

ABSTRACTHierarchically porous materials are of interest in a wide range of applications. If the materials are electronic, or ionic conductors, such materials are of interest as electrodes for use in fuel cells. Using hierarchically porous silica as templates, we have demonstrated the formation of hierarchically porous metal and metal oxide structures. Through the control of the synthesis conditions, we have produced partial replicas ca. 1 cubic centimeter in volume, in which two macroporous networks are separated by a nanoporous membrane. The macroporous network in the silica template is known to be bicontinuous. Our underlying model predicts that the second, induced, macroporous network should be similarly bicontinuous.Micrometer resolution X-ray tomography of the whole sample confirms that the synthesis produces one bicontinuous macroporous network, and is consistent with the existence of a second set of macropores. Preliminary experiments were carried out using FIB/SEM serial tomography to image the second macropore network, however, the length scale of the structures is such that this approach it is unable to firmly establish that the second macropore network is bicontinuous throughout the entire sample volume.

From Graphite to Porous Carbon Containing Nanoparticles through Chemical Reactions

1996 ◽  
Vol 431 ◽  
Author(s):  
C. C. Hung ◽  
J. Corbin
Keyword(s):  
Metal Oxides ◽  
Surface Area ◽  
Porous Carbon ◽  
Chemical Properties ◽  
Atomic Ratio ◽  
Synthesis Process ◽  
Metal Chlorides ◽  
Graphite Fluoride ◽  
Surface Areas ◽  
Individual Nanoparticles

AbstractPorous carbon containing large quantities of separated individual nanoparticles (2–100 nm) was produced. The chemical process includes fluorination or oxygenation of graphite, and then exposing the product (graphite fluoride or graphite oxide) to metal chlorides. The nanoparticles were metal halides or metal oxides, which could contain dopants if they were added during the synthesis process. The metal to carbon atomic ratio was in the range of 1 (3–6). The chlorides used in this research include those of Pd, Zn, Al and Li. Depending on the synthesis process, the carbon pores could be either filled with the nanoparticles, resulting in near-zero surface area and high metal concentration, or partially filled with nanoparticles, resulting in large surface areas. In this report, near zero surface areas were observed for a product of LiCl in carbon, and a surface area of 75 m2/g was observed for the product of γ- Al2O3 in carbon. Heating these products in 1 atm air allowed the nanoparticles to become fuse together in the form of metal oxide while the carbon was oxidized, producing metal oxides which have the same shape as the carbon precursors (fibers, fabrics, or powder) and large surface areas. These products are potentially useful in the area of batteries, high temperature gas sensors, and catalysts. Also, these products could be used to examine individual nanopartidles, whose electrical, optical, and chemical properties differ from those of their single crystal or amorphous counterparts

scholarly journals Efficient Removal of Cr(VI) with Fe/Mn Mixed Metal Oxide Nanocomposites Synthesized by a Grinding Method

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Wang Weilong ◽  
Fu Xiaobo
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Adsorption Capacity ◽  
Mixed Metal Oxide ◽  
Mixed Metal Oxides ◽  
Mixed Metal ◽  
Surface Areas ◽  
Grinding Method ◽  
Xps Characterization ◽  
Enhanced Adsorption

Fe/Mn mixed metal oxides were synthesized facilely by a grinding method and were characterized by TEM, XRD, XPS, and BET. The characterization results revealed that mixed metal oxides were mainly composed of not highly crystallized Fe2O3and Mn3O4nanoparticles with a diameter about 3–5 nm. The specific BET surface areas of the composite were affected by the amounts of KCl diluent in the preparation process and about 268 m2/g of the composite can be achieved. Compared with metal oxide adsorbents existent, the composites showed good adsorption capacity, stability, and regeneration activity for Cr(VI) removal. The enhanced adsorption capacity was speculated to be ascribed to the synergistic effect of the mixed metal oxides. By monitoring the valence change in the adsorption process using XPS characterization, the mechanism for Cr(VI) removal on the composites was found to be a combination of electrostatic attraction and ion exchange. The above results demonstrated that the synthesized metal oxides nanocomposite is of great potential for Cr(VI) removal in the fields of remediation of environmental problems.

scholarly journals Synthesis and Dissolution of Metal Oxides in Ionic Liquids and Deep Eutectic Solvents

Molecules ◽  
2019 ◽  
Vol 25 (1) ◽  
pp. 78 ◽  
Author(s):  
Janine Richter ◽  
Michael Ruck
Keyword(s):  
Ionic Liquids ◽  
Low Temperature ◽  
Metal Oxide ◽  
Metal Oxides ◽  
High Temperatures ◽  
Deep Eutectic Solvents ◽  
Wide Range ◽  
Oxide Phases

Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. This review gives an overview about the scientific approaches of the synthesis as well as the dissolution of metal oxides in ILs and DESs. A wide range of metal oxides along with numerous ILs and DESs are covered by this research. With ILs and DESs being involved, many metal oxide phases as well as different particle morphologies were obtained by means of relatively simple reactions paths. By the development of acidic task-specific ILs and DESs, even difficultly soluble metal oxides were dissolved and, hence, made accessible for downstream chemistry. Especially the role of ILs in these reactions is in the focus of discussion.

scholarly journals Tris(2-Aminoethyl)Amine/Metal Oxides Hybrid Materials—Preparation, Characterization and Catalytic Application

Molecules ◽  
2020 ◽  
Vol 25 (20) ◽  
pp. 4689
Author(s):  
Katarzyna Stawicka ◽  
Maria Ziolek
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Hybrid Materials ◽  
Knoevenagel Condensation ◽  
Catalyst Activity ◽  
Textural Properties ◽  
Nitrogen Adsorption ◽  
Surface Areas ◽  
Strength Of Interaction ◽  
Adsorption Desorption

Three different metal oxides (basic MgO, basic-acidic Al2O3 and acidic-basic Nb2O5) characterized by comparable surface areas (MgO—130 m2/g; Al2O3—172 m2/g and Nb2O5—123 m2/g) and pore systems (domination of mesopores with narrow pore size distribution) were modified with tris(2-aminoethyl)amine (TAEA) via two methods: (i) direct anchoring of amine on metal oxide and (ii) anchoring of amine on metal oxide functionalized with (3-chloropropyl)trimethoxysilane. The obtained hybrid materials were characterized in terms of effectiveness of modifier anchoring (elemental analysis), their structural/textural properties (nitrogen adsorption/desorption, XRD), acidity/basicity of support (2-propanol dehydration and dehydrogenation, dehydration and cyclization of 2,5-hexanedione), states of modifier deposited on supports (XPS, FTIR, UV–VIS) and the strength of interaction between the modifier and the support (TG/DTG). It was evidenced that acidic-basic properties of metal oxides as well as the procedure of modification with TAEA determined the ways of amine anchoring and the strength of its interaction with the support. The obtained hybrid materials were tested in Knoevenagel condensation between furfural and malononitrile. The catalysts based on MgO showed superior activity in this reaction. It was correlated with the way of TAEA anchoring on basic MgO and the strength of modifier anchoring on the support. To the best of our knowledge tris(2-aminoethyl)amine has not been used as a modifier of solid supports for enhancement of the catalyst activity in Knoevenagel condensation.

scholarly journals Construction and Transition Metal Oxide Loading of Hierarchically Porous Carbon Aerogels

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2066
Author(s):  
Jintian Wang ◽  
Xinyang Ruan ◽  
Jiahao Qiu ◽  
Hao Liang ◽  
Xingzhong Guo ◽  
...  
Keyword(s):  
Hydrochloric Acid ◽  
Transition Metal ◽  
Metal Oxide ◽  
Porous Carbon ◽  
Metal Oxide Nanoparticles ◽  
Transition Metal Oxide ◽  
Bet Surface Area ◽  
Carbon Aerogels ◽  
Oxide Nanoparticles ◽  
Hierarchically Porous

Hierarchically porous carbon aerogels (CAs) were prepared by organic condensation gelation method combined with atmospheric drying and pore-formation technology, followed by a carbonization process. With as-prepared CAs as substrate, the transition metal oxide nanoparticles loaded CAs composites (MnO2/Mn2O3@CA and Ni/NiO@CA) were achieved by means of liquid etching method combined with heat treatment, respectively. The catalyst, pore-forming agent and etching have important roles on the apparent density and pore structure of CAs. The hydrochloric acid (catalyst) significantly accelerates the gelation process and influences the size and distribution of macropores, whereas the addition of PEG2000 (pore-forming agent) and the etching of liquid solution leads to the formation of mesopore structure in CAs. Appropriate amounts of hydrochloric acid and PEG2000 allow the formation of hierarchically porous CAs with a BET surface area of 482.9 m2·g−1 and a macropore size of 11.3 μm. After etching and loading, the framework of CAs is etched to become a mesoporous structure, and the transition metal oxide nanoparticles can be uniformly loaded in CAs. These resultant composites have promising application in super capacitor, electrocatalysis, batteries and other fields.

Synthesis of Hierarchically Porous Silica and Metal Oxide Beads Using Emulsion-Templated Polymer Scaffolds

2004 ◽  
Vol 16 (22) ◽  
pp. 4245-4256 ◽  
Author(s):  
H. Zhang ◽  
G. C. Hardy ◽  
Y. Z. Khimyak ◽  
M. J. Rosseinsky ◽  
A. I. Cooper
Keyword(s):  
Metal Oxide ◽  
Porous Silica ◽  
Polymer Scaffolds ◽  
Hierarchically Porous

Metal-oxide based ammonia gas sensors: A review

2020 ◽  
Vol 10 ◽  
Author(s):  
Priya Gupta ◽  
Savita Maurya ◽  
Narendra Kumar Pandey ◽  
Vernica Verma
Keyword(s):  
Metal Oxide ◽  
Metal Oxides ◽  
Gas Sensor ◽  
Gas Sensors ◽  
Review Paper ◽  
Gas Sensing ◽  
Gas Sensitivity ◽  
Ammonia Gas ◽  
Ammonia Sensing ◽  
Ammonia Gas Sensors

: This review paper encompasses a study of metal-oxide and their composite based gas sensors used for the detection of ammonia (NH3) gas. Metal-oxide has come into view as an encouraging choice in the gas sensor industry. This review paper focuses on the ammonia sensing principle of the metal oxides. It also includes various approaches adopted for increasing the gas sensitivity of metal-oxide sensors. Increasing the sensitivity of the ammonia gas sensor includes size effects and doping by metal or other metal oxides which will change the microstructure and morphology of the metal oxides. Different parameters that affect the performances like sensitivity, stability, and selectivity of gas sensors are discussed in this paper. Performances of the most operated metal oxides with strengths and limitations in ammonia gas sensing application are reviewed. The challenges for the development of high sensitive and selective ammonia gas sensor are also discussed.

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