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Punctured Two-Dimensional Sheets for Harvesting Blue Energy

ACS Nano - 9 hours 3 min ago

ACS NanoDOI: 10.1021/acsnano.7b06657
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Cu2IrO3: A New Magnetically Frustrated Honeycomb Iridate

Journal of the American Chemical SocietyDOI: 10.1021/jacs.7b06911
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Recent Advances in Sensing Applications of Graphene Assemblies and Their Composites

Advanced Functional Materials - 17 hours 27 min ago
Abstract

Development of next-generation sensor devices is gaining tremendous attention in both academia and industry because of their broad applications in manufacturing processes, food and environment control, medicine, disease diagnostics, security and defense, aerospace, and so forth. Current challenges include the development of low-cost, ultrahigh, and user-friendly sensors, which have high selectivity, fast response and recovery times, and small dimensions. The critical demands of these new sensors are typically associated with advanced nanoscale sensing materials. Among them, graphene and its derivatives have demonstrated the ideal properties to overcome these challenges and have merged as one of the most popular sensing platforms for diverse applications. A broad range of graphene assemblies with different architectures, morphologies, and scales (from nano-, micro-, to macrosize) have been explored in recent years for designing new high-performing sensing devices. Herein, this study presents and discusses recent advances in synthesis strategies of assembled graphene-based superstructures of 1D, 2D, and 3D macroscopic shapes in the forms of fibers, thin films, and foams/aerogels. The fabricated state-of-the-art applications of these materials in gas and vapor, biomedical, piezoresistive strain and pressure, heavy metal ion, and temperature sensors are also systematically reviewed and discussed, and their sensing performance is compared.

Graphene assemblies with different 1D, 2D, and 3D architectures are extensively used to construct a broad range of sensing devices with advanced functionalities and performances. The chemical approaches play vital roles not only in assembling graphene into desired macroscopic structures, but also in enhancing sensing performance of gas/vapor, bio-, piezoresistive, and other sensor devices.

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Multiscale Nanoparticle Assembly: From Particulate Precise Manufacturing to Colloidal Processing

Advanced Functional Materials - 17 hours 30 min ago
Abstract

Nanoparticle assembly and colloidal processing are two techniques with the goal to fabricate materials and devices from preformed particles. While colloidal processing has become an integral part of ceramic processing, nanoparticle assembly is still mainly limited to academic interests. It typically starts with the precise synthesis of building blocks, which are generally not only considerably smaller than those used for colloidal processing, but also better defined in terms of size, shape, and size distribution. Their arrangement into 1D, 2D, and 3D architectures is performed with great accuracy well beyond what is achieved by colloidal processing. At the same time, the final assembly is not sintered such that the intrinsic, nanospecific properties of the initial building blocks are preserved or even lead to collective behavior. However, in contrast to colloidal processing the structures accessible by nanoparticle assembly are often limited to a small length scale. The review presents selected examples of nanoparticle assembly and colloidal processing with the goal to reveal the capabilities of these two techniques to fabricate novel materials from preformed building blocks, and also to demonstrate the immense opportunities that would arise if the two methods could be combined with each other.

Nanoparticle assembly and colloidal processing are two complementary techniques for the fabrication of materials and devices from preformed particles. This Review provides an overview of the capabilities of these two approaches and discusses the fascinating opportunities that would emerge if the two methods could be combined.

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Hematite Photoanodes: Synergetic Enhancement of Light Harvesting and Charge Management by Sandwiched with Fe2TiO5/Fe2O3/Pt Structures

Advanced Functional Materials - 17 hours 33 min ago
Abstract

Efficient charge separation and transport as well as high light absorption are key factors that determine the efficiency of photoelectrochemical (PEC) water splitting devices. Here, a PEC device consisting of a hematite nanoporous film deposited on Pt nanopillars, followed by the decoration with an Fe2TiO5 passivation layer, is designed and fabricated. This structure can largely improve the light absorption in the composite materials, and significantly enhance the water oxidation performance of hematite photoanodes. The Fe2TiO5 thin shell and Pt underlayer significantly improve the interfacial charge transfer while minimizing the hole-migration length in Fe2O3 photoanodes, leading to a drastically increased photocurrent density. Specially, the Fe2TiO5/Fe2O3/Pt photoanode yields an excellent photoresponse for PEC water splitting reactions with 1.0 and 2.4 mA cm−2 obtained at 1.23 and 1.6 VRHE under AM 1.5G illumination in 1 m KOH. The resulting photocurrents are 2.5 times enhanced compared to a pristine Fe2O3 photoanode of the same geometry. These results demonstrate a synergistic charge transfer effect of Fe2TiO5 and Pt layers on hematite for the improvement of PEC water oxidation.

Synergetic enhancement of light harvesting and charge separation. The formation of a Fe2TiO5 thin shell and a Pt underlayer on hematite photoanodes largely improves light absorption in the composite material, and also significantly enhances the water oxidation performance. The Fe2TiO5 thin shell and Pt underlayer significantly improve the interfacial and surface charge separation efficiencies with minimized influence on the hole-migration property of Fe2O3 photoanodes.

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Hierarchical Porous NC@CuCo Nitride Nanosheet Networks: Highly Efficient Bifunctional Electrocatalyst for Overall Water Splitting and Selective Electrooxidation of Benzyl Alcohol

Advanced Functional Materials - 17 hours 46 min ago
Abstract

Highly active and stable bifunctional electrocatalysts for overall water splitting are important for clean and renewable energy technologies. The development of energy-saving electrocatalysts for hydrogen evolution reaction (HER) by replacing the sluggish oxygen evolution reaction (OER) with a thermodynamically favorable electrochemical oxidation (ECO) reaction has attracted increasing attention. In this study, a self-supported, hierarchical, porous, nitrogen-doped carbon (NC)@CuCo2Nx/carbon fiber (CF) is fabricated and used as an efficient bifunctional electrocatalyst for both HER and OER in alkaline solutions with excellent activity and stability. Moreover, a two-electrode electrolyzer is assembled using the NC@CuCo2Nx/CF as an electrocatalyst at both cathode and anode electrodes for H2 production and selective ECO of benzyl alcohol with high conversion and selectivity. The excellent electrocatalytic activity is proposed to be mainly due to the hierarchical architecture beneficial for exposing more catalytic active sites, enhancing mass transport. Density functional theoretical calculations reveal that the adsorption energies of key species can be modulated due to the synergistic effect between CoN and CuN. This work provides a reference for the development of high-performance bifunctional electrocatalysts for simultaneous production of H2 and high-value-added fine chemicals.

Hierarchical porous nitrogen-doped carbon@CuCo2Nx/carbon fiber serving as an efficient bifunctional electrocatalyst for overall water splitting and selective electrooxidation of benzyl alcohol with excellent activity and stability is reported. The outstanding electrocatalytic performance is mainly due to the hierarchical architecture and the synergistic effects between the Co5.47N, Cu3N nanoparticles.

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Stereospecific Allylic Functionalization: The Reactions of Allylboronate Complexes with Electrophiles

Journal of the American Chemical SocietyDOI: 10.1021/jacs.7b10240
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Clay Minerals—Ionic Liquids, Nanoarchitectures, and Applications

Advanced Functional Materials - 17 hours 47 min ago
Abstract

Clay minerals, whose world resources are extremely large, have the potential to be more exploited as the basis for functional materials. Of interest are their interactions with ionic liquids (ILs). These compounds have found a large number of applications in the last few decades due to unique properties, such as low vapor pressure, high thermal stability, and remarkable solvation abilities. In the case of the swelling smectites, the organic cation of ILs can replace interlayer cations and find applications in the preparation of nanocomposites. This feature article is mainly focused on kaolinite, a nonswelling 1:1 phyllosilicate, whose layers are essentially neutral. Consequently, the intercalation of ILs involves both cation and anion. The organic cations can be designed to bear hydroxyl groups that will react with the aluminol internal surface of kaolinite, resulting in ionic liquids not only intercalated but also grafted. The resulting nanohybrid materials are characterized by a fixed, rigid, constrained 2D structure, whose dimension can be tuned by the size of the organic cation, whereas the anion is exchangeable. These materials are used for sensing applications such as the specific detection of anions as well as their quantitative analysis. They are also used as catalyst support for nanoparticles.

Clay mineral and ionic liquid structures are judiciously combined to produce nanohybrid materials with various properties and applications. The precise control of the functionalities of the materials obtained from kaolinite in particular makes them promising for a variety of applications. The essential achievements in the clay minerals modification by ionic liquids and applications of the resulting nanohybrid materials are presented here.

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Thiabicyclononane-Based Antimicrobial Polycations

Journal of the American Chemical SocietyDOI: 10.1021/jacs.7b07596
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Hollow Mesoporous Functional Hybrid Materials: Fascinating Platforms for Advanced Applications

Advanced Functional Materials - 17 hours 47 min ago
Abstract

Functionalized hollow nano- and microspheres containing both hollow and mesoporous structures are fascinating materials for a broad range of applications, such as nanoparticle collectors, catalysis, drug delivery systems, immobilization of biomolecules, and the adsorption and separation of gas and pollutants, because of their empty interior. These hollow mesoporous silica materials are synthesized mainly via soft- and hard-templating routes and are usually modified with a range of organic functional groups (SH, NH2, CN, CH3, CC, benzene, fluorine linked organoalkylsilanes, and ethane-, amine, benzene, and biphenyl-bridged silanes) to improve their performance in many applications. This article outlines the most advanced applications of silica-based and functionalized hollow mesoporous materials that are reported in the last 3 years (January 2014–June 2017). The high applicability of hollow materials in various fields is discussed, including drug delivery and cancer therapy, bioimaging, adsorption/separation, catalysis, thermal and electrical insulators, anticorrosion, sensors, fuel cells, proton conductors, membrane, optics, superhydrophobic surfaces, and fire safety.

Functionalized hollow mesoporous materials are one of most interesting materials in recent years because they work as a fascinating platform for controlled morphology and properties. This article overviews the recent research trends on the silica-based and functionalized hollow mesoporous silica along with their advanced applications, such as drug delivery, adsorption, catalysis, thermal and electrical insulators, anticorrosion, bioimaging, and sensors.

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Fabrication and Properties of a Free-Standing Two-Dimensional Titania

Journal of the American Chemical SocietyDOI: 10.1021/jacs.7b08229
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Triplet Transfer Mediates Triplet Pair Separation during Singlet Fission in 6,13-Bis(triisopropylsilylethynyl)-Pentacene

Advanced Functional Materials - 17 hours 49 min ago
Abstract

Triplet population dynamics of solution cast films of isolated polymorphs of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pn) provide quantitative experimental evidence that triplet excitation energy transfer is the dominant mechanism for correlated triplet pair (CTP) separation during singlet fission. Variations in CTP separation rates are compared for polymorphs of TIPS-Pn with their triplet diffusion characteristics that are controlled by their crystal structures. Since triplet energy transfer is a spin-forbidden process requiring direct wavefunction overlap, simple calculations of electron and hole transfer integrals are used to predict how molecular packing arrangements would influence triplet transfer rates. The transfer integrals reveal how differences in the packing arrangements affect electronic interactions between pairs of TIPS-Pn molecules, which are correlated with the relative rates of CTP separation in the polymorphs. These findings suggest that relatively simple computations in conjunction with measurements of molecular packing structures may be used as screening tools to predict a priori whether new types of singlet fission sensitizers have the potential to undergo fast separation of CTP states to form multiplied triplets.

Ultrafast spectroscopy of 6,13-bis(triisopropylsilylethynyl)-pentacene polymorphs reveals triplet transfer as the mechanism of correlated triplet pair separation in singlet fission. Crystal structures, solved through both X-ray and computational methods, explain differences in their triplet separation characteristics. Charge transfer integrals form a metric for assessing triplet pair separation, codifying a new approach to a priori screening of emerging singlet fission materials.

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Glutathione-Activatable and O2/Mn2+-Evolving Nanocomposite for Highly Efficient and Selective Photodynamic and Gene-Silencing Dual Therapy

Advanced Functional Materials - 17 hours 53 min ago
Abstract

Photodynamic therapy (PDT) has been applied in cancer treatment by converting O2 into reactive singlet oxygen (1O2) to kill cancer cells. However, the effectiveness of PDT is limited by the fact that tumor hypoxia causes an inadequate O2 supply, and the overexpressed glutathione (GSH) in cancer cells consumes reactive oxygen species. Herein, a multifunctional hybrid system is developed for selective and highly efficient PDT as well as gene-silencing therapy using a novel GSH-activatable and O2/Mn2+-evolving nanocomposite (GAOME NC). This system consists of honeycomb MnO2 (hMnO2) nanocarrier loaded with catalase, Ce6, and DNAzyme with folate label, which can specifically deliver payloads into cancer cells. Once endocytosed, hMnO2 carriers are reduced by the overexpressed GSH to Mn2+ ions, resulting in the reduction of GSH level and disintegration of GAOME NC. The released catalases then trigger the breakdown of endogenous H2O2 to generate O2, which is converted by the excited Ce6 into 1O2. The self-sufficiency of O2 and consumption of GSH effectively enhance the PDT efficacy. Moreover, DNAzyme is freed for gene silencing in the presence of self-generated Mn2+ ions as cofactors. The rational synergy of enhanced PDT and gene-silencing therapy remarkably improve the in vitro and in vivo therapeutic efficacy of cancers.

A cell-specific, glutathione (GSH)-activatable, and O2/Mn2+-evolving nanocomposite consisting of honeycomb MnO2 carrier carrying catalase, Ce6, and DNAzyme with folate label is developed for not only the enhanced photodynamic therapy by both self-sufficiency of O2 and the depletion of cellular GSH induced by MnO2 carrier, but also the coupled Mn2+-DNAzyme-mediated gene-silencing therapy with the self-generated Mn2+ ions as cofactors.

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Functional nanoparticles exploit the bile acid pathway to overcome multiple barriers of the intestinal epithelium for oral insulin delivery

Biomaterials - 20 hours 56 min ago
Publication date: January 2018
Source:Biomaterials, Volume 151

Author(s): Weiwei Fan, Dengning Xia, Quanlei Zhu, Xiuying Li, Shufang He, Chunliu Zhu, Shiyan Guo, Lars Hovgaard, Mingshi Yang, Yong Gan

Oral absorption of protein/peptide-loaded nanoparticles is often limited by multiple barriers of the intestinal epithelium. In addition to mucus translocation and apical endocytosis, highly efficient transepithelial absorption of nanoparticles requires successful intracellular trafficking, especially to avoid lysosomal degradation, and basolateral release. Here, the functional material, deoxycholic acid-conjugated chitosan, is synthesized and loaded with the model protein drug insulin into deoxycholic acid-modified nanoparticles (DNPs). The DNPs designed in this study are demonstrated to overcome multiple barriers of the intestinal epithelium by exploiting the bile acid pathway. In Caco-2 cell monolayers, DNPs are internalized via apical sodium-dependent bile acid transporter (ASBT)-mediated endocytosis. Interestingly, insulin degradation in the epithelium is significantly prevented due to endolysosomal escape of DNPs. Additionally, DNPs can interact with a cytosolic ileal bile acid-binding protein that facilitates the intracellular trafficking and basolateral release of insulin. In rats, intravital two-photon microscopy also reveals that the transport of DNPs into the intestinal villi is mediated by ASBT. Further pharmacokinetic studies disclose an oral bioavailability of 15.9% in type I diabetic rats after loading freeze-dried DNPs into enteric-coated capsules. Thus, deoxycholic acid-modified chitosan nanoparticles can overcome multiple barriers of the intestinal epithelium for oral delivery of insulin.
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