scholarly journals Hierarchical Structures from Inorganic Nanocrystal Self-Assembly for Photoenergy Utilization

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Yun-Pei Zhu ◽  
Tie-Zhen Ren ◽  
Tian-Yi Ma ◽  
Zhong-Yong Yuan
Keyword(s):  
Self Assembly ◽  
Architectural Design ◽  
High Surface ◽  
Hierarchical Structures ◽  
Research Progress ◽  
Structural Hierarchy ◽  
Surface Areas ◽  
Nanobuilding Blocks ◽  
And Performance ◽  
Nanocrystal Assembly

Self-assembly has emerged as a powerful strategy for controlling the structure and physicochemical properties of ensembles of inorganic nanocrystals. Hierarchical structures from nanocrystal assembly show collective properties that differ from individual nanocrystals and bulk samples. Incorporation of structural hierarchy into nanostructures is of great importance as a result of enhancing mass transportation, reducing resistance to diffusion, and high surface areas for adsorption and reaction, and thus much effort has been devoted to the exploration of various novel organizing schemes through which inorganic porous structure with architectural design can be created. In this paper, the recent research progress in this field is reviewed. The general strategies for the synthesis of hierarchical structures assembled from nanobuilding blocks are elaborated. The well-defined hierarchical structures provide new opportunities for optimizing, tuning, and/or enhancing the properties and performance of these materials and have found applications in photoenergy utilization including photodegradation, photocatalytic H2production, photocatalytic CO2conversion, and sensitized solar cells, and these are discussed illustratively.

scholarly journals Surfactant Templated Mesoporous Hybrid Thin Films

2000 ◽  
Vol 628 ◽  
Author(s):  
Hongyou Fan ◽  
Yunfeng Lu ◽  
Roger A. Assink ◽  
Gabriel P. Lopez ◽  
C. Jeffrey Brinker
Keyword(s):  
Thin Film ◽  
Self Assembly ◽  
High Surface ◽  
Homogeneous Solution ◽  
Dip Coating ◽  
Inorganic Hybrid ◽  
Surface Areas ◽  
Hybrid Silica ◽  
Hybrid Thin Films ◽  
Coating Procedure

ABSTRACTOrganic/inorganic hybrid mesoporous films exhibiting ordered mesophases were prepared by a simple dip-coating procedure. Beginning with a homogeneous solution of tetraethoxysilane, organoalkoxysilane ((R'Si(OR)3, R' is a non-hydrolyzable functional ligand) surfactant, we relied on solvent evaporation to induce micellization and continuous self-assembly into hybrid silica-surfactant thin film mesophases. Surface acoustic wave (SAW)-based nitrogen sorption measurements indicate that the films have high surface areas and unimodal pore diameters after removal of surfactants.

scholarly journals Structure and Performance of Carbon Aerogel Electrodes

1994 ◽  
Vol 349 ◽  
Author(s):  
R.W. Pekala ◽  
S.T. Mayer ◽  
J.F. Poco ◽  
J.L. Kaschmitier
Keyword(s):  
Large Fraction ◽  
High Surface ◽  
Carbon Aerogel ◽  
High Energy ◽  
Structural Features ◽  
Carbon Aerogels ◽  
Cluster Assembly ◽  
Surface Areas ◽  
And Performance ◽  
Small Clusters

ABSTRACTThe chemistry and physics of small clusters of atoms (1-100 nm) has received considerable attention in recent years because these assemblies often have properties between the molecular and bulk solid-state limits. The different properties can be explained in terms of the large fraction of atoms that are at the surface of a cluster as compared to the interior. Although the synthesis and properties of metal and semiconductor clusters, metallocarbohedrenes, fullerenes, and nanotubes are the subject of extensive investigations, little attention has been paid to cluster-assembled porous materials. This oversight is of particular interest to us since we believe that aerogels are one of the few monolithic materials presently available where the benefits of cluster assembly can be demonstrated. In particular, the unique optical, thermal, acoustic, mechanical, and electrical properties of aerogels are directly related to their nanostructure, which is composed of interconnected particles (3-30 nrm) with small interstitial pores (< 50 nm). This structure leads to extremely high surface areas (400-1100 m2/g) with a large fraction of the atoms covering the surface of the interconnected particles. As a result of these structural features, carbon aerogels are finding applications as electrodes in supercapacitors with high energy and power densities.

Wood and Paper as Materials for the 21st Century

2009 ◽  
Vol 1187 ◽  
Author(s):  
Philip Jones ◽  
Theodore H Wegner
Keyword(s):  
Self Assembly ◽  
Hierarchical Structures ◽  
High Strength ◽  
Forest Products ◽  
Building Blocks ◽  
Forest Products Industry ◽  
Strength Performance ◽  
New Science ◽  
And Performance ◽  
Long Fibers

AbstractWood and paper are ubiquitous in societies around the world and are largely taken for granted as part of traditional industries with no new science to learn. Many of the technologies used in the forest products industry have been gained empirically through experience. The complexities of wood are now yielding to newer tools and we are beginning to see how the mechanical, optical and other physical properties of wood are related to hierarchical structures based on 2 to 10 nm diameter several hundred nm long fibers of nanocrystalline cellulose (NCC). The liberation of these NCC’s is allowing their re-assembly into remarkably strong structures. Examples will be given of the nature of these building blocks and structures assembled from them. Examples will include nanocomposites as well as very high strength “paper”. Paper is another example of a process whereby nanofibrils are released and then re-assembled with the use of “retention, drainage and formation aides” to make substrates we call paper with remarkable strength to weight performance. Other disciplines call this process “self-assembly” and the “aids” as necessary surfactants and additives to control structure and performance. Glossy magazine papers, for example, have approximately 10 micron thick coatings of white minerals and latex binders which are increasingly of nano dimensions. The coatings are assembled in structures to provide optical barrier performance (opacity) as well as controlled ink interaction with the necessary strength to survive printing and handling. These coatings are frequently similar in structure to seashells and, from this knowledge, progress has been made in understanding the mechanisms at play in achieving higher strength coatings. More recently kaolin clays have been introduced with mean crystal thicknesses in the range 20 to 40 nm instead of the usual 100 to 140 nm. These clays show useful strength performance and represent what may be called pragmatic nanoclays. Novel chemistries based on biomimetic learnings are emerging to displace the conventional starch or latex binders. Examples will be given of protocols for moving toward higher strength systems.

scholarly journals Enzymes@ZIF-8 Nanocomposites with Protection Nanocoating: Stability and Acid-Resistant Evaluation

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 27 ◽  
Author(s):  
Yuxiao Feng ◽  
Le Zhong ◽  
Muhammad Bilal ◽  
Zhilei Tan ◽  
Ying Hou ◽  
...  
Keyword(s):  
Self Assembly ◽  
High Surface ◽  
Phosphate Buffer Solution ◽  
Acid Resistance ◽  
Initial Activity ◽  
Buffer Solution ◽  
Solution Ph ◽  
Practical Applications ◽  
Surface Areas ◽  
And Storage

Zeolitic imidazole framework-8 (ZIF-8) with tunable pore sizes and high surface areas have recently emerged as a promising support for immobilizing enzymes. However, the instability in the aqueous acidic environment and difficulty of recovery has limited their practical applications in some cases. In this study, catalase/ZIF-8 composites with a protective nanocoating were prepared by the controlled self-assembly of silanes or coordination complexes (tannic acid (TA) and Fe3+). The properties of the catalase (CAT)/ZIF-8 composites with a protective nanocoating were also determined. The recovered activity of CAT/ZIF-8 and CAT/ZIF-8 with protective nanocoating was 70% and 65%, respectively. Compared with the conventional CAT/ZIF-8 composites, CAT/ZIF-8 with protective nanocoating exhibited excellent acid resistance. For example, after treatment for 60 min in phosphate buffer solution (pH 3.0), CAT/ZIF-8 composites only maintained 20% of their initial activity (about 12 U/mg). However, CAT/ZIF-8 with a protective nanocoating could still retain about 50% of its initial activity (about 10 U/mg). Meanwhile, the thermostability and storage stability of the CAT/ZIF-8 composites was enhanced significantly due to the presence of nanocoating compared with conventional CAT/ZIF-8. More importantly, the CAT/ZIF-8 with a protective nanocoating retained 40% of its initial activity after 7 cycles, whereas CAT/ZIF-8 only retained 8% of the initial activity. The approach in this study could be an efficient strategy to prepare enzyme/ZIF-8 composites with both high acid resistance and excellent recyclability.

High temperature and water-based evaporation-induced self-assembly approach for facile and rapid synthesis of nanocrystalline mesoporous TiO2

2014 ◽  
Vol 2 (38) ◽  
pp. 15912-15920 ◽  
Author(s):  
Wei Wang ◽  
Dongthanh Nguyen ◽  
Haibo Long ◽  
Guoqiang Liu ◽  
Song Li ◽  
...  
Keyword(s):  
High Temperature ◽  
Self Assembly ◽  
High Surface ◽  
Mesoporous Tio2 ◽  
Rapid Synthesis ◽  
Surface Areas ◽  
Water Based ◽  
Evaporation Induced Self Assembly ◽  
Large Mesopores

Through a high-temperature and water-based EISA (HW-EISA) approach, mesoporous TiO2 with high surface areas, ultra-large mesopores/pore volumes and tuneable bi-crystallinity (anatase plus rutile) can be facilely prepared in a ternary templating system (peroxotitanic acid/P123/H2O).

Biomimetic materials: An introduction

1992 ◽  
Vol 50 (2) ◽  
pp. 1020-1021 ◽  
Author(s):  
M. Sarikaya ◽  
J. T. Staley ◽  
I. A. Aksay
Keyword(s):  
Self Assembly ◽  
Structural Control ◽  
Hierarchical Structures ◽  
Ceramic Composites ◽  
Advanced Materials ◽  
Length Scale ◽  
Spider Webs ◽  
Biomimetic Materials ◽  
Synthetic Materials ◽  
All Ceramic

Biomimetics is an area of research in which the analysis of structures and functions of natural materials provide a source of inspiration for design and processing concepts for novel synthetic materials. Through biomimetics, it may be possible to establish structural control on a continuous length scale, resulting in superior structures able to withstand the requirements placed upon advanced materials. It is well recognized that biological systems efficiently produce complex and hierarchical structures on the molecular, micrometer, and macro scales with unique properties, and with greater structural control than is possible with synthetic materials. The dynamism of these systems allows the collection and transport of constituents; the nucleation, configuration, and growth of new structures by self-assembly; and the repair and replacement of old and damaged components. These materials include all-organic components such as spider webs and insect cuticles (Fig. 1); inorganic-organic composites, such as seashells (Fig. 2) and bones; all-ceramic composites, such as sea urchin teeth, spines, and other skeletal units (Fig. 3); and inorganic ultrafine magnetic and semiconducting particles produced by bacteria and algae, respectively (Fig. 4).

A Highly Crystalline Anthracene-Based MOF-74 Series Featuring Electrical Conductivity and Luminescence

2019 ◽  
Author(s):  
Patricia Scheurle ◽  
Andre Mähringer ◽  
Andreas Jakowetz ◽  
Pouya Hosseini ◽  
Alexander Richter ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Metal Ions ◽  
Light Emission ◽  
Block Design ◽  
High Surface ◽  
Visible Spectrum ◽  
Building Blocks ◽  
Divalent Metal Ions ◽  
Conductivity Enhancement ◽  
Surface Areas

Recently, a small group of metal-organic frameworks (MOFs) has been discovered featuring substantial charge transport properties and electrical conductivity, hence promising to broaden the scope of potential MOF applications in fields such as batteries, fuel cells and supercapacitors. In combination with light emission, electroactive MOFs are intriguing candidates for chemical sensing and optoelectronic applications. Here, we incorporated anthracene-based building blocks into the MOF-74 topology with five different divalent metal ions, that is, Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, resulting in a series of highly crystalline MOFs, coined ANMOF-74(M). This series of MOFs features substantial photoluminescence, with ANMOF-74(Zn) emitting across the whole visible spectrum. The materials moreover combine this photoluminescence with high surface areas and electrical conductivity. Compared to the original MOF-74 materials constructed from 2,5-dihydroxy terephthalic acid and the same metal ions Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, we observed a conductivity enhancement of up to six orders of magnitude. Our results point towards the importance of building block design and the careful choice of the embedded MOF topology for obtaining materials with desired properties such as photoluminescence and electrical conductivity.

Kinetic Control of Interpenetration in Fe-Biphenyl-4,4′-dicarboxylate MOFs by Coordination and Oxidation Modulation

2018 ◽  
Author(s):  
Dominic Bara ◽  
Claire Wilson ◽  
Max Mörtel ◽  
Marat M. Khusniyarov ◽  
ben slater ◽  
...  
Keyword(s):  
Self Assembly ◽  
Surface Areas ◽  
Metal Precursors ◽  
Additional Coordination ◽  
Fine Control ◽  
Multiple Alternative ◽  
Metal Organic ◽  
Dft Simulations ◽  
High Valent ◽  
And Control

Phase control in the self-assembly of metal-organic frameworks (MOFs) – materials wherein organic ligands connect metal ions or clusters into network solids with potential porosity – is often a case of trial and error. Judicious control over a number of synthetic variables is required to select for the desired topology and control features such as interpenetration and defectivity, which have significant impact on physical properties and application. Herein, we present a comprehensive investigation of self-assembly in the Fe-biphenyl-4,4'-dicarboxylate system, demonstrating that coordination modulation, the addition of competing ligands into solvothermal syntheses, can reliably tune between the kinetic product, non-interpenetrated MIL-88D(Fe), and the thermodynamic product, two-fold interpenetrated MIL-126(Fe). DFT simulations reveal that correlated disorder of the terminal anions on the metal clusters in the interpentrated phase results in H-bonding between adjacent nets and is the thermodynamic driving force for its formation. Coordination modulation slows self-assembly and therefore selects the thermodynamic product MIL-126(Fe), while offering fine control over defectivity, inducing mesoporosity, but electron microscopy shows the MIL-88D(Fe) phase persists in many samples despite not being evident in diffraction experiments, suggesting its presence accounts for the lower than predicted surface areas reported for samples to date. Interpenetration control is also demonstrated by utilizing the 2,2'-bipyridine-5,5'-dicarboxylate linker; DFT simulations show that it is energetically prohibitive for it to adopt the twisted conformation required to form the interpenetrated phase, and are confirmed by experimental data, although multiple alternative phases are identified due to additional coordination of the Fe cations to the N-donors of the ligand. Finally, we introduce oxidation modulation – the concept of using metal precursors in a different oxidation state to that found in the final MOF – as a further protocol to kinetically control self-assembly. Combining coordination and oxidation modulation allows the synthesis of pristine MIL-126(Fe) with BET surface areas close to the predicted maximum capacity for the first time, suggesting that combining the two may be a powerful methodology for the controlled self-assembly of high-valent MOFs.<br><br>

scholarly journals Rugae-like FeP nanocrystal assembly on a carbon cloth: an exceptionally efficient and stable cathode for hydrogen evolution

Nanoscale ◽  
2015 ◽  
Vol 7 (25) ◽  
pp. 10974-10981 ◽  
Author(s):  
Xiulin Yang ◽  
Ang-Yu Lu ◽  
Yihan Zhu ◽  
Shixiong Min ◽  
Mohamed Nejib Hedhili ◽  
...  
Keyword(s):  
Gas Phase ◽  
Surface Area ◽  
Hydrogen Evolution ◽  
Hydrogen Generation ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Efficiency ◽  
Carbon Cloth ◽  
Nanocrystal Assembly

High surface area FeP nanosheets on a carbon cloth were prepared by gas phase phosphidation of electroplated FeOOH, which exhibit exceptionally high catalytic efficiency and stability for hydrogen generation.

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