Three in One: Superoleophilic, Chemically and Mechanically Resistant ZIF-7 and ZIF-11 Percolation Networks for Selective Permeation of Oils and Chlorinated Solvents.

Imbuing superwetting functions to organic-inorganic hybrid networks displaying chemical resistance, self-cleaning ability, and selective permeation of liquids has received increasing attention in recent years. Here we report superhydrophobic ZIF-7 and ZIF-11 on multilayer fluorinated graphene (FG) nanosheets with long-lasting water-repellent features. By exploring the solution processing of these chemically resistant dispersions, superoleophilic FG-ZIF-7 stainless steel mesh (FG-ZIF-7-SSM) and FG-ZIF-11 over cotton cloth (FG-ZIF-11-CC) possessing superior adhesion were fabricated. These permselective oil-liking prototypes were explored toward mesitylene and crude oil pickup from chemically harsh marine conditions such as seawater, acidic water, and alkaline water, with a separation efficiency of 96-94% up to 10 cycles. Furthermore, using an FG-ZIF-11-CC-wrapped glass pipet, upward diffusion of chloroform from sea, acidic, and alkaline water in 45 s was demonstrated with a separation efficacy of 94% up to 20 cycles. In addition to the chemical resistance and reusability, the mechanical stability of FG-ZIF-7-SSM and FG-ZIF-11-CC was investigated through folding, tape peeling, and dragging through sandpaper up to 250 cycles, showing no signs of changes in the hydrophobic responses. This research sheds light on the application of physiochemically resistant percolation coatings based on fluorinated graphene multilayers supporting ZIF-7 and ZIF-11 toward oil/water separation.

Application of lamellar nickel hydroxide membrane as a tunable platform for ionic thermoelectric studies.

The recent trend in thermoelectric literature suggests that ionic thermoelectric (i-TE) materials are ideal for directly converting low-grade waste heat into electricity. Here, we developed a unique platform for i-TE studies by stacking two-dimensional sheets of ß-Ni(OH)2 prepared by a bottom-up method. The lamellar membrane of ß-Ni(OH)2 (Ni-M) itself does not display significant thermovoltages, but when doped with mobile anion-generating species (like aminopropyl functionalized magnesium phyllosilicate or organic halide salts), it exhibits significant negative Seebeck coefficient (up to -13.7 ± 0.2 mV K-1). Similarly, upon doping with cation-generating species like poly(4-styrene sulfonic acid) (PSS), it displays positive Seebeck coefficient values (up to +12 ± 1.9 mV K-1). The positive and negative i-TE materials prepared by doping Ni-M are assembled into ionic thermopiles capable of generating thermovoltages up to 1 V, at ΔT = 12 K. The Ni-M-based nanofluidic systems demonstrated an additional path of electricity harvesting by connecting colder zones of the positive and negative i-TE materials with other ion conducting membranes. In contrast to organic polymer-based i-TE systems, the Ni-M based system exhibited consistent performance despite being exposed to high temperatures (∼200 °C, 5 minutes).

Porous Fluorinated Graphene and ZIF-67 Composites with Hydrophobic-Oleophilic Properties Towards Oil and Organic Solvent Sorption.

Designing hydrophobic-oleophilic sorbent materials have gained significant interest owing to its potential applications in self-cleaning technologies particularly oil-water separation. The crucial factors remain in the future research of designing materials with high performance hydrophobicoleophilic properties include facile synthesis, low-density, reusability and ecofriendly. Herein, we develop porous hydrophobic-oleophilic nanoarchitecture based on 2D fluorinated graphene (FG) supported cobalt based zeolite imidazole framework (ZIF-67) by solution assisted self-assembly. The key features of the work include in-situ growth and assembly of ZIF-67 over functionalized fluorinated graphene f-FG macrostructures, high surface area and solution processable and spray coated sponge. Methodical characterization of f-FG@ZIF-67 composites, followed by measuring water contact angles by contact angle goniometer. Furthermore, the assessment of sorption capacity of oils and organics followed by oil recovery from oil-water mixtures, excellent chemical and physical stabilities were displayed by these hydrophobic-oleophilic composites.

Facile synthesis and rheological characterization of nanocomposite hyaluronan-organoclay hydrogels.

We report a facile methodology for the synthesis of inorganic-organic hydrogels based on integrative assembly of aminopropyl magnesium phyllosilicate (aminoclay) and sodium salt of hyaluronic acid. The viscoelastic materials produced by electrostatic interactions and crosslinking of hyaluronan in the presence of exfoliated synthetic organoclay results in the formation of gel-like behavior retaining a high amount of water. This was confirmed by a rheological study revealing significant dominance of the elastic response over the entire deformation frequency range used. The mechanical strength of the aminoclay-hyaluronan hydrogels was found to be higher than that for related materials based on poly(vinylpyrrolidone)-aminoclay hydrogels.

NZVI modified magnetic filter paper with high redox and catalytic activities for advanced water treatment technologies.

The in situ synthesis of air-stable zero-valent iron nanoparticles (NZVI) embedded in cellulose fibers leads to the assembly of highly reactive magnetic filter papers. These engineered materials display a wide range of applications in the treatment of wastewater and drinking water, including chromium removal, phenol degradation, environmental bioremediation, and catalysis.

Quaternized carbon dot-modified graphene oxide for selective cell labelling--controlled nucleus and cytoplasm imaging.

Cationic quaternized carbon dots (QCDs) and anionic graphene oxide sheets (GO) are combined via non-covalent interactions following a self-assembly pathway to form highly biocompatible and fluorescent hybrid materials. These hybrids act as selective probes with controlled labelling of the cell nucleus or cytoplasm depending on the QCD loading.

Carbon spheres assisted synthesis of porous oxides with foam-like architecture.

Herein, we report a facile route for the synthesis of foam-like porous oxides using carbon spheres and polyvinylpyrrolidone (PVP) as sacrificial templates. The as-prepared porous structures were characterized by XRD, FESEM, TEM and BET methods. These foam-like macroporous oxides are formed through the fusion of oxide nanoparticles around the gas bubbles liberated during the combustion of composites and show good BET surface areas.

Aminoclay-supported copper nanoparticles for 1,3-dipolar cycloaddition of azides with alkynes via click chemistry.

Aminoclay supported copper nanoparticles are effective in promoting [3+2] cycloaddition of azides with terminal alkynes to produce the corresponding 1,2,3-triazoles in excellent yields. The copper nanoparticles are highly reactive in water and can be recycled for four cycles with consistent activity.

Amphiphilic aminoclay-RGO hybrids: a simple strategy to disperse a high concentration of RGO in water.

The aqueous dispersion of graphene or reduced graphene oxide (RGO) is very much important to realize the full potential of these materials in many fields. Herein we present a simple route to prepare highly water dispersible aminoclay-RGO (AC-RGO) hybrids by the in situ condensation of aminoclay over graphene oxide (GO) followed by reduction with hydrazine hydrate. The resultant hybrids are stable in aqueous media even at concentrations up to 7.5 mg RGO per mL. To the best of our knowledge this is the highest concentration of an aqueous dispersion of RGO. Significantly, the hybrids are amphiphilic in nature and show simultaneous adsorption of Cytochrome C through hydrophobic interaction and DNA through electrostatic interaction. This strategy opens up new possibilities for the prospect of RGO in catalysis and biomedical applications.

Highly pure solid-state white-light emission from solution-processable soft-hybrids.

Highly pure and solution processable white-light-emitting hybrids are presented. These soft-hybrids are designed by an organic-inorganic supramolecular co-assembly in water. White-light emission is achieved by partial energy transfer (ET) between donor and acceptor molecules anchored on the inorganic component. The unique and remarkable processability feature of these hybrids is demonstrated by painting/writing onto large glass and flexible plastic substrates.

Kinetics and mechanism of electrochemical oxygen reduction using platinum/clay/Nafion catalyst layer for polymer electrolyte membrane fuel cells.

This work demonstrates the use of amino functionalized Mg-phyllosilicate clay/Nafion nanocomposite film embedded with Pt nanoparticles (Pt/AC/N) for catalyzing oxygen reduction reaction (ORR) in sulphuric acid medium. Pt/AC/N nanocomposite films were surface characterized using transmission electron microscope. Cyclic and linear scan voltammetry studies were carried out under hydrodynamic conditions taking rotating-ring disc electrode (RRDE) as the working electrode. The effects of clay content, Pt mass loading, electrode rotation rate, and temperature on the ORR kinetics were studied. The Tafel slopes were found to vary between 118 and 126 mV dec(-1) indicating a good ORR kinetics. The exchange current density values calculated after mass transfer correction ranged from 5.8×10(-7) to 2.4×10(-6) A cm(-2). From the RRDE disc currents, Koutecky-Levich plots were constructed and the ORR mechanism was found to follow a four electron path with minimum H(2)O(2) formation of ∼1.6%. The effect of temperature on ORR kinetics was found at 25, 40, and 50°C. The energy of activation calculated to be 7.68 kJ mol(-1) and comparable to the standard Pt/C catalyzed ORR systems.

Pd-aminoclay nanocomposite as an efficient recyclable catalyst for hydrogenation and Suzuki cross coupling reactions.

A highly water dispersible Pd-aminoclay nanocomposite is found to be effective catalytic system for the hydrogenation of alpha,beta-unsaturated carbonyl compounds and Suzuki coupling reactions in aqueous media. The catalytic hydrogenation of alpha,beta-unsaturated carbonyl compounds proceeds at room temperature to afford the corresponding products in excellent yields with high chemoselectivity. The cross coupling of aryl bromides and iodides with aryl boronic acids proceeds efficiently under aqueous conditions at 90 degrees C to afford the corresponding biaryls in excellent yields with high selectivity. The Suzuki reaction proceeds smoothly even in the absence of external base due to the basic nature of the catalyst support. The catalyst could be easily recovered and recycled three times without a significant loss of activity in hydrogenation and Suzuki cross coupling reactions.

Improved oxygen reduction reaction catalyzed by Pt/Clay/Nafion nanocomposite for PEM fuel cells.

A novel Pt nanoparticle (Pt NP) embedded aminoclay/Nafion (Pt/AC/N) nanocomposite catalyst film was prepared for oxygen reduction reaction by sol-gel method. The prepared nanocomposite films were surface characterized using XRD and TEM and thermal stability was studied by TGA. The prepared film has firmly bound Pt NP and could exhibit an improved electro-reduction activity compared to vulcan carbon/Nafion supported Pt NP (Pt/VC/N). Moreover, the Pt/AC/N film possessed good stability in the acidic environment. The limiting current density of the Pt/AC/N film with 35.4 µg/cm(2) of Pt loading was found to be 4.2 mA/cm(2), which is 30% higher than that of the Pt/VC/N. The maximum H2O2 intermediate formation was found to be ∼1.6% and the reaction found to follow a four electron transfer mechanism. Accelerated durability test for 2000 potential cycles showed that ca. 78% of initial limiting current was retained. The results are encouraging for possible use of the Pt/AC/N as the free-standing electrocatalyst layer for polymer electrolyte membrane fuel cells.

Light-harvesting hybrid assemblies.

Light-harvesting hybrids have gained much importance as they are considered as potential mimics for photosynthetic systems. In this Concept article we introduce the design concepts involved in the building up of light-harvesting hybrids; these resemble the well-studied organic-based assemblies for energy transfer. We have structured this article into three parts based on the strategies adopted in the synthesis of hybrid assemblies, as covalent, semicovalent, and noncovalent procedures. Furthermore, the properties and structural features of the hybrids and analogous organic assemblies are compared. We also emphasize the challenges involved in the processability of these hybrid materials for device applications and present our views and results to address this issue through the design of soft-hybrids by a solution-state, noncovalent, self-assembly process.

Honey derivatized Au and Ag nanoparticles and evaluation of its antimicrobial activity.

Biomolecules hosting the synthesis of nanoparticles has achieved considerable attention in recent decades due to their abundant availability, excellent biocompatibility and low toxicity. The present study demonstrates a rapid, cost-effective and eco-friendly fabrication of gold and silver nanoparticles at room temperature using natural honey as a source of stabilizing and reducing agent. The nanoparticles obtained were unambiguously characterized by using various characterization techniques such as transmission electron microscopy (TEM), UV-Visible absorption spectroscopy, X-ray diffraction and energy dispersive (EDX) X-ray analysis. The average size of Au and Ag nanoparticles are 10 and 12 nm respectively. Ag nanoparticles capped by honey exhibited superior antimicrobial activity while Au nanoparticles revealed passable activity against pathogenic bacteria and Candida albicans, including multi-resistant strains for the first time.

Carbon nanocage: super-adsorber of intercalators for DNA protection.

In this research, we report the binding behaviors of two kinds of intercalators, methyl violet and 3,6-diaminoacridine hydrochloride, to various mesoporous materials, carbon nanocage, mesoporous carbon CMK-3, activated carbon, and mesoporous silica SBA-15. Due to its unique cage type structure, carbon nanocage shows greater adsorption capacity than the other adsorbents. In addition, competitive adsorption of methyl violet between DNA and mesoporous materials confirmed that carbon nanocage can very efficiently inhibit intercalation of methyl violet by DNA. Carbon nanocage might then be useful for entrapment of harmful aromatic molecules.

Base-selective adsorption of nucleosides to pore-engineered nanocarbon, carbon nanocage.

Selective molecular recognition is an important subject in supramolecular science as well as in practical applications such as sensing, drug delivery, and biomedical processes. In this research we have investigated adsorption behavior of nucleosides (adenosine, guanosine, and thymidine) onto various porous supports. When compared with mesoporous silica, porous carbons exhibit superior adsorptive performance. We serendipitously observed a pronounced selectivity between purine-base and pyrimidine-base nucleosides by carbon naonocage. These findings are useful for design of materials for applications in adsorption-based separations and as column stationary phases for separation of costly and important biomolecules.

Open-mouthed metallic microcapsules: exploring performance improvements at agglomeration-free interiors.

Although artificial capsule structures have been thoroughly investigated, functionality at the surfaces of their interiors has been surprisingly overlooked. In order to exploit this aspect of capsular structure, we here report the breakthrough fabrication of metallic (platinum) microcapsules with sufficient accessibility and electroactivity at both interior and exterior surfaces (open-mouthed platinum microcapsules), and also we demonstrate improvements in electrochemical and catalytic functions to emphasize the practical importance of our concept. The open-mouthed platinum microcapsules were prepared by template synthesis using polystyrene spheres, where surface-fused crystalline nanoparticles formed a capsule shell. Subsequent removal of the polystyrene spheres induced formation of mouth-like openings. The open-mouthed platinum microcapsules exhibit a substantial increase of their electrode capability for methanol oxidation and catalytic activities for carbon monoxide (CO) oxidation. Notably, activity loss during CO oxidation due to undesirable particle agglomeration can be drastically suppressed using the open-mouthed microcapsules.