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Synthesis and Luminescent Properties of Europium Complexes Covalently Bonded to Hybrid Materials Based on MCM-41 and Poly(Ionic Liquids)

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Xiaolong Zheng

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Meiyu Wang

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Qiuping Li

Materials 2018, 11(5), 677; https://doi.org/10.3390/ma11050677 - 26 Apr 2018

Cited by 18 | Viewed by 3552

Abstract

Due to the wide potential application in the fields of sensing, lighting materials, and optical–electrical multifunctional devices, rare earth complex hybrid materials have been studied extensively over the past decades. A poly(ionic liquid)/mesoporous-based hybrid system which has been functionalized by the covalently linked [...] Read more.

Due to the wide potential application in the fields of sensing, lighting materials, and optical–electrical multifunctional devices, rare earth complex hybrid materials have been studied extensively over the past decades. A poly(ionic liquid)/mesoporous-based hybrid system which has been functionalized by the covalently linked europium complexes was reported here. Through surface modification with a coupling agent bearing an vinyl group, MCM-41 was chosen as the carrier matrix for poly(ionic liquids) (PILs) and europium compounds, and based on that, novel luminescent hybrid materials were prepared by confining the ionic liquid and europium complexes into the inorganic Si–O frameworks. The resulting organic/inorganic materials are chemically bonded hybrids which show good photoluminescent properties such as broad excitation spectra, line-like emission spectra, and long luminescence lifetimes. The PILs/MCM-41/Eu³⁺ hybrid reported here is a rare earth multifunctional material which is believed to have potential applications in the field of optical–electrical materials. Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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Open AccessArticle

Core Level Spectra of Organic Molecules Adsorbed on Graphene

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Abhilash Ravikumar

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Gian Paolo Brivio

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Guido Fratesi

Materials 2018, 11(4), 518; https://doi.org/10.3390/ma11040518 - 29 Mar 2018

Cited by 2 | Viewed by 3650

Abstract

We perform first principle calculations based on density functional theory to investigate the effect of the adsorption of core-excited organic molecules on graphene. We simulate Near Edge X-ray absorption Fine Structure (NEXAFS) and X-ray Photoemission Spectroscopy (XPS) at the N and C edges [...] Read more.

We perform first principle calculations based on density functional theory to investigate the effect of the adsorption of core-excited organic molecules on graphene. We simulate Near Edge X-ray absorption Fine Structure (NEXAFS) and X-ray Photoemission Spectroscopy (XPS) at the N and C edges for two moieties: pyridine and the pyridine radical on graphene, which exemplify two different adsorption characters. The modifications of molecular and graphene energy levels due to their interplay with the core-level excitation are discussed. We find that upon physisorption of pyridine, the binding energies of graphene close to the adsorption site reduce mildly, and the NEXAFS spectra of the molecule and graphene resemble those of gas phase pyridine and pristine graphene, respectively. However, the chemisorption of the pyridine radical is found to significantly alter these core excited spectra. The C 1s binding energy of the C atom of graphene participating in chemisorption increases by ∼1 eV, and the C atoms of graphene alternate to the adsorption site show a reduction in the binding energy. Analogously, these C atoms also show strong modifications in the NEXAFS spectra. The NEXAFS spectrum of the chemisorbed molecule is also modified as a result of hybridization with and screening by graphene. We eventually explore the electronic properties and magnetism of the system as a core-level excitation is adiabatically switched on. Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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Open AccessFeature PaperArticle

TiO₂@PEI-Grafted-MWCNTs Hybrids Nanocomposites Catalysts for CO₂ Photoreduction

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Materials 2018, 11(2), 307; https://doi.org/10.3390/ma11020307 - 20 Feb 2018

Cited by 12 | Viewed by 4719

Abstract

Anatase (TiO₂) and multiwalled carbon nanotubes bearing polyethylenimine (PEI) anchored on their surface were hybridized in different proportions according to a sol-gel method. The resulting nanocomposites (TiO₂@PEI-MWCNTs), characterized by BET, XRD, XPS, SEM, and UV techniques, were found efficient [...] Read more.

Anatase (TiO₂) and multiwalled carbon nanotubes bearing polyethylenimine (PEI) anchored on their surface were hybridized in different proportions according to a sol-gel method. The resulting nanocomposites (TiO₂@PEI-MWCNTs), characterized by BET, XRD, XPS, SEM, and UV techniques, were found efficient catalysts for CO₂ photoreduction into formic and acetic acids in water suspension and under visible light irradiation. PEI-grafted nanotubes co-catalysts are believed to act as CO₂ activators by forming a carbamate intermediate allowing to accomplish the first example in the literature of polyamines/nanotubes/TiO₂ mediated CO₂ photoreduction to carboxylic acids. Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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Open AccessFeature PaperArticle

Improved Photo-Ignition of Carbon Nanotubes/Ferrocene Using a Lipophilic Porphyrin under White Power LED Irradiation

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Selma Elaine Mazzetto

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Giuseppe Mele

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Antonio Paolo Carlucci

Materials 2018, 11(1), 127; https://doi.org/10.3390/ma11010127 - 13 Jan 2018

Cited by 5 | Viewed by 3597

Abstract

The aim of this work is to investigate and characterize the photo-ignition process of dry multi-walled carbon nanotubes (MWCNTs) mixed with ferrocene (FeCp₂) powder, using an LED (light-emitting diode) as the light source, a combination that has never been used, to [...] Read more.

The aim of this work is to investigate and characterize the photo-ignition process of dry multi-walled carbon nanotubes (MWCNTs) mixed with ferrocene (FeCp₂) powder, using an LED (light-emitting diode) as the light source, a combination that has never been used, to the best of our knowledge. The ignition process was improved by adding a lipophilic porphyrin (H₂Pp) in powder to the MWCNTs/FeCp₂ mixtures—thus, a lower ignition threshold was obtained. The ignition tests were carried out by employing a continuous emission and a pulsed white LED in two test campaigns. In the first, two MWCNT typologies, high purity (HP) and industrial grade (IG), were used without porphyrin, obtaining, for both, similar ignition thresholds. Furthermore, comparing ignition thresholds obtained with the LED source with those previously obtained with a Xenon (Xe) lamp, a significant reduction was observed. In the second test campaign, ignition tests were carried out by means of a properly driven and controlled pulsed XHP70 LED source. The minimum ignition energy (MIE) of IG-MWCNTs/FeCp₂ samples was determined by varying the duration of the light pulse. Experimental results show that ignition is obtained with a pulse duration of 110 ms and a MIE density of 266 mJ/cm². The significant reduction of the MIE value (10–40%), observed when H₂Pp in powder form was added to the MWCNTs/FeCp₂ mixtures, was ascribed to the improved photoexcitation and charge transfer properties of the lipophilic porphyrin molecules. Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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Open AccessFeature PaperArticle

Continuous-Flow Production of Injectable Liposomes via a Microfluidic Approach

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Materials 2017, 10(12), 1411; https://doi.org/10.3390/ma10121411 - 10 Dec 2017

Cited by 40 | Viewed by 4234

Abstract

Injectable liposomes are characterized by a suitable size and unique lipid mixtures, which require time-consuming and nonstraightforward production processes. The complexity of the manufacturing methods may affect liposome solubility, the phase transition temperatures of the membranes, the average particle size, and the associated [...] Read more.

Injectable liposomes are characterized by a suitable size and unique lipid mixtures, which require time-consuming and nonstraightforward production processes. The complexity of the manufacturing methods may affect liposome solubility, the phase transition temperatures of the membranes, the average particle size, and the associated particle size distribution, with a possible impact on the drug encapsulation and release. By leveraging the precise steady-state control over the mixing of miscible liquids and a highly efficient heat transfer, microfluidic technology has proved to be an effective and direct methodology to produce liposomes. This approach results particularly efficient in reducing the number of the sizing steps, when compared to standard industrial methods. Here, Microfluidic Hydrodynamic Focusing chips were produced and used to form liposomes upon tuning experimental parameters such as lipids concentration and Flow-Rate-Ratios (FRRs). Although modelling evidenced the dependence of the laminar flow on the geometric constraints and the FRR conditions, for the specific formulation investigated in this study, the lipids concentration was identified as the primary factor influencing the size of the liposomes and their polydispersity index. This was attributed to a predominance of the bending elasticity modulus over the vesiculation index in the lipid mixture used. Eventually, liposomes of injectable size were produced using microfluidic one-pot synthesis in continuous flow. Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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Open AccessFeature PaperArticle

A New Ion-Imprinted Chitosan-Based Membrane with an Azo-Derivative Ligand for the Efficient Removal of Pd(II)

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Materials 2017, 10(10), 1133; https://doi.org/10.3390/ma10101133 - 26 Sep 2017

Cited by 28 | Viewed by 4552

Abstract

Herein, we described the synthesis of a novel ion-imprinted membrane for the detection of palladium(II) prepared through the glutaraldehyde crosslinking of chitosan with a 4-[(4-Hydroxy)phenylazo]benzenesulfonic acid ligand trapped into the membrane. The imprinting technology was used to improve adsorption capacity and adsorption selectivity, [...] Read more.

Herein, we described the synthesis of a novel ion-imprinted membrane for the detection of palladium(II) prepared through the glutaraldehyde crosslinking of chitosan with a 4-[(4-Hydroxy)phenylazo]benzenesulfonic acid ligand trapped into the membrane. The imprinting technology was used to improve adsorption capacity and adsorption selectivity, and was combined with some advantages of the developed membrane, such as low cost and ease of preparation, water-friendly synthesis, and high biocompatible chitosan material. The membranes were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-ray Spectrometry (EDS). The results obtained showed a high swelling ratio with a maximum value of 16.4 (1640%) at pH 4 with a strong pH dependence. Batch rebinding experiments gave a maximum adsorption capacity of 101.6 mg of Pd(II) per gram of imprinted membrane. The Pd(II) adsorption behavior was well-described by a Langmuir model with a theoretical maximum adsorption capacity of 93.48 mg g⁻¹, similar to the experimental one. Finally, a selectivity study versus Ag(I), Pb(II), and Fe(III) ions demonstrated a good selectivity of chitosan-imprinted membrane towards Pd(II). Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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Open AccessArticle

New ZnO@Cardanol Porphyrin Composite Nanomaterials with Enhanced Photocatalytic Capability under Solar Light Irradiation

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Viviane Gomes Pereira Ribeiro

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Ana Maria Pereira Marcelo

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Kássia Teixeira Da Silva

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Fernando Luiz Firmino Da Silva

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João Paulo Ferreira Mota

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João Paulo Costa Do Nascimento

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Antonio Sérgio Bezerra Sombra

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Claudenilson Da Silva Clemente

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Giuseppe Mele

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Luigi Carbone

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Selma Elaine Mazzetto

Materials 2017, 10(10), 1114; https://doi.org/10.3390/ma10101114 - 21 Sep 2017

Cited by 19 | Viewed by 5401

Abstract

This work describes the synthesis, characterization, and photocatalytic activity of new composite nanomaterials based on ZnO nanostructures impregnated by lipophlilic porphyrins derived from cashew nut shell liquid (CNSL). The obtained nanomaterials were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier [...] Read more.

This work describes the synthesis, characterization, and photocatalytic activity of new composite nanomaterials based on ZnO nanostructures impregnated by lipophlilic porphyrins derived from cashew nut shell liquid (CNSL). The obtained nanomaterials were characterized by X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and steady-state photoluminescence spectra (PL). The results confirm nanostructures showing average diameter of 55 nm and an improved absorption in the visible region. Further, the FTIR analysis proved the existence of non-covalent interactions between the porphyrin molecules and ZnO. The photocatalytic activity of prepared photocatalysts was investigated by degradation of rhodamine B (RhB) in aqueous solution under visible light irradiation and natural sunlight. It was demonstrated that the photocatalytic activity increases in the presence of the porphyrins and, also, depends on the irradiation source. The development of composite photocatalysts based on porphyrins derived from CNSL provides an alternative approach to eliminate efficiently toxic wastes from water under ambient conditions. Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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Review

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Open AccessReview

Magnetic Particle Filled Elastomeric Hybrid Composites and Their Magnetorheological Response

by

Seung Hyuk Kwon

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Jin Hyun Lee

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Hyoung Jin Choi

Materials 2018, 11(6), 1040; https://doi.org/10.3390/ma11061040 - 19 Jun 2018

Cited by 40 | Viewed by 6256

Abstract

The magnetorheological (MR) elastomer as a hard and soft hybrid functional material, a composite material consisting of magnetic hard particles embedded in elastomeric soft matrix, is a branch of MR materials that are functional smart materials rapidly responding to external magnetic fields. These [...] Read more.

The magnetorheological (MR) elastomer as a hard and soft hybrid functional material, a composite material consisting of magnetic hard particles embedded in elastomeric soft matrix, is a branch of MR materials that are functional smart materials rapidly responding to external magnetic fields. These tunable properties of MR elastomers facilitate a variety of applications. In this brief review paper, in addition to general information on the MR elastomers, recent research not only on a wide variety of MR elastomeric systems focusing on various magnetic particles, elastomeric matrices, additives and particle modification methods, but also on their characteristics including MR properties from dynamic oscillation tests is covered along with their mechanical properties such as the Payne effect, tensile strength and engineering applications. Full article

(This article belongs to the Special Issue Hard and Soft Hybrid Functional Materials)

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