Showing papers on "Nanocages published in 2016"
TL;DR: Novel Ni-Co-Prussian-blue-analog nano-cages consisting of pyramid-like walls were prepared via a facile chemical etching process with ammonia at room temperature and exhibit enhanced electrocatalytic activity and excellent stability toward the oxygen-evolution reaction.
Abstract: Novel Ni-Co-Prussian-blue-analog nano-cages consisting of pyramid-like walls were prepared via a facile chemical etching process with ammonia at room temperature. After annealing in air, the derived Ni-Co mixed oxide nanocages exhibit enhanced electrocatalytic activity and excellent stability toward the oxygen-evolution reaction.
524 citations
TL;DR: The hollow CH@LDH polyhedra with complex shell structures not only maximize the advantages of hollow nanostructures for encapsulating a high content of sulfur, but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution.
Abstract: Lithium–sulfur (Li-S) batteries have been considered as a promising candidate for next-generation electrochemical energy-storage technologies because of their overwhelming advantages in energy density. Suppression of the polysulfide dissolution while maintaining a high sulfur utilization is the main challenge for Li–S batteries. Here, we have designed and synthesized double-shelled nanocages with two shells of cobalt hydroxide and layered double hydroxides (CH@LDH) as a conceptually new sulfur host for Li–S batteries. Specifically, the hollow CH@LDH polyhedra with complex shell structures not only maximize the advantages of hollow nanostructures for encapsulating a high content of sulfur (75 wt %), but also provide sufficient self-functionalized surfaces for chemically bonding with polysulfides to suppress their outward dissolution. When evaluated as cathode material for Li–S batteries, the CH@LDH/S composite shows a significantly improved electrochemical performance.
508 citations
TL;DR: In this article, a metal-organic-framework-engaged strategy was used to synthesize Co nanoparticle-embedded carbon@Co9S8 double-shelled nanocages (Co-C@Co 9S8 DSNCs).
Abstract: Hollow nanostructures with a complex interior and superb structural tenability offer great advantages for constructing advanced catalysts. Herein, we report the designed synthesis of novel Co nanoparticle-embedded carbon@Co9S8 double-shelled nanocages (Co-C@Co9S8 DSNCs) by a metal–organic-framework-engaged strategy. Uniform zeolitic imidazolate framework (ZIF-67)@amorphous CoS yolk–shelled structures are first fabricated and then converted to Co-C@Co9S8 DSNCs by thermal annealing in N2 flow. The Co-C nanocages inside Co9S8 shells function as the active centers for the oxygen reduction reaction (ORR). The Co9S8 shells prevent the Co-C active centers from aggregation while acting as nanoreactors. As a result, the Co-C@Co9S8 DSNCs exhibit excellent performance for the ORR in terms of low over-potential, high current density, excellent stability and methanol tolerance capability.
465 citations
TL;DR: Hybrid sp2 carbon with a graphene backbone and graphitic carbon nanocages is demonstrated as an ideal host for sulfur in Li-S batteries, because it serves as highly efficient electrochemical nanoreactors as well as polysulfides reservoirs.
Abstract: Hybrid sp2 carbon with a graphene backbone and graphitic carbon nanocages (G-GCNs) is demonstrated as an ideal host for sulfur in Li-S batteries, because it serves as highly efficient electrochemical nanoreactors as well as polysulfides reservoirs. The as-obtained S/(G-GCNs) with high S content exhibits superior high-rate capability (765 mA h g-1 at 5 C) and long-cycle life over 1000 cycles.
385 citations
TL;DR: In this paper, a facile strategy to synthesize porous FexCo3−xO4 nanocages by heating Prussian blue analogues FeyCo1−y[Co(CN)6]0.67 nH2O nanospheres with tunable size and morphology was reported.
Abstract: Here we report a facile strategy to synthesize porous FexCo3−xO4 nanocages by heating Prussian blue analogues FeyCo1−y[Co(CN)6]0.67 nH2O nanospheres with tunable size and morphology. The iron doping amount had significant influence on the final morphology and the most uniform nanocages were obtained from x = 0.8. The catalytic performance of the nanocages was thoroughly evaluated by activation of peroxymonosulfate (PMS) for removal of bisphenol A (BPA) in water. The influence of different process parameter on the BPA degradation efficiency was examined and the catalytic stability was tested. The BPA degradation pathway was proposed based on GC–MS and LC–MS results. The involved radicals were identified through radical scavenging experiments and electron paramagnetic resonance spectroscopy. Mossbauer and XPS techniques were applied to illustrate the catalytic mechanism and B-site CoII on the surface of FexCo3−xO4 nanocages was determined as the main factor for PMS activation. Results indicate that porous FexCo3−xO4 nanocages are available to serve as alternative environmentally friendly catalysts for pollutants removal by activation of PMS.
372 citations
TL;DR: A significant inverse correlation between the size of a protein and its activity enhancement is observed and is consistent with a model wherein distal polyanionic surfaces of the nanocage enhance the stability of active enzyme conformations through the action of a strongly bound hydration layer.
Abstract: Cells routinely compartmentalize enzymes for enhanced efficiency of their metabolic pathways. Here we report a general approach to construct DNA nanocaged enzymes for enhancing catalytic activity and stability. Nanocaged enzymes are realized by self-assembly into DNA nanocages with well-controlled stoichiometry and architecture that enabled a systematic study of the impact of both encapsulation and proximal polyanionic surfaces on a set of common metabolic enzymes. Activity assays at both bulk and single-molecule levels demonstrate increased substrate turnover numbers for DNA nanocage-encapsulated enzymes. Unexpectedly, we observe a significant inverse correlation between the size of a protein and its activity enhancement. This effect is consistent with a model wherein distal polyanionic surfaces of the nanocage enhance the stability of active enzyme conformations through the action of a strongly bound hydration layer. We further show that DNA nanocages protect encapsulated enzymes against proteases, demonstrating their practical utility in functional biomaterials and biotechnology.
340 citations
TL;DR: The results demonstrate that the bioinspired multifunctional CuS-Fn NCs have potential as clinically translatable cancer theranostics and could provide a noninvasive, highly sensitive, and quantitative in vivo guiding method for cancer photothermal therapies in experimental and clinical settings.
Abstract: It is essential to control the size and morphology of nanoparticles strictly in nanomedicine. Protein cages offer significant potential for templated synthesis of inorganic nanoparticles. In this study, we successfully synthesized ultrasmall copper sulfide (CuS) nanoparticles inside the cavity of ferritin (Fn) nanocages by a biomimetic synthesis method. The uniform CuS–Fn nanocages (CuS–Fn NCs) showed strong near-infrared absorbance and high photothermal conversion efficiency. In quantitative ratiometric photoacoustic imaging (PAI), the CuS–Fn NCs exhibited superior photoacoustic tomography improvements for real-time in vivo PAI of entire tumors. With the incorporation of radionuclide 64Cu, 64CuS–Fn NCs also served as an excellent PET imaging agent with higher tumor accumulation compared to free copper. Following the guidance of PAI and PET, CuS–Fn NCs were applied in photothermal therapy to achieve superior cancer therapeutic efficiency with good biocompatibility both in vitro and in vivo. The results de...
311 citations
TL;DR: A routine to synthesize ultrathin icosahedral Pt-enriched nanocage structure that outperforms the cubic and octahedral nanocages reported in the literature, demonstrating the superiority of the icosahed nanocAGE structure.
Abstract: Cost-efficient utilization of Pt in the oxygen reduction reaction (ORR) is of great importance for the potential industrial scale demand of proton-exchange membrane fuel cells. Designing a hollow structure of a Pt catalyst offers a great opportunity to enhance the electrocatalytic performance and maximize the use of precious Pt. Herein we report a routine to synthesize ultrathin icosahedral Pt-enriched nanocages. In detail, the Pt atoms were conformally deposited on the surface of Pd icosahedral seeds, followed by selective removal of the Pd core by a concentrated HNO3 solution. The icosahedral Pt-enriched nanocage that is a few atomic layers thick includes the merits of abundant twin defects, an ultrahigh surface/volume ratio, and an ORR-favored Pt{111} facet, all of which have been demonstrated to be promoting factors for ORR. With a 10 times higher specific activity and 7 times higher mass activity, this catalyst shows more extraordinary ORR activity than the commercial Pt/C. The ORR activity of icosah...
299 citations
TL;DR: Owing to the good mechanical flexibility and pronounced structure stability of carbon nanocages-encapsulated Co9 S8 , the as-obtained HCSP⊂GCC exhibit superior Li-ion storage.
Abstract: Novel electrode materials consisting of hollow cobalt sulfide nanoparticles embedded in graphitic carbon nanocages (HCSP⊂GCC) are facilely synthesized by a top-down route applying room-temperature synthesized Co-based zeolitic imidazolate framework (ZIF-67) as the template. Owing to the good mechanical flexibility and pronounced structure stability of carbon nanocages-encapsulated Co9 S8 , the as-obtained HCSP⊂GCC exhibit superior Li-ion storage. Working in the voltage of 1.0-3.0 V, they display a very high energy density (707 Wh kg(-1) ), superior rate capability (reversible capabilities of 536, 489, 438, 393, 345, and 278 mA h g(-1) at 0.2, 0.5, 1, 2, 5, and 10C, respectively), and stable cycling performance (≈26% capacity loss after long 150 cycles at 1C with a capacity retention of 365 mA h g(-1) ). When the work voltage is extended into 0.01-3.0 V, a higher stable capacity of 1600 mA h g(-1) at a current density of 100 mA g(-1) is still achieved.
291 citations
TL;DR: In this paper, a facile method of synthesizing IF-MoS2 hollow structures with a diameter of ∼100 nm was described, which can provide large expandable spaces for volume changes occurring during the cycles.
Abstract: Inorganic fullerene (IF)-like structured materials have attracted considerable attention for electrochemical energy storage and conversion. In this report, we describe a facile method of synthesizing IF-MoS2 hollow structures with a diameter of ∼100 nm by a facile solution-phase reduction process to obtain a hollow MoSx precursor under ambient pressures before subsequent annealing of the material at high temperatures to form IF-MoS2 nanocages. TEM images at different reaction stages reveal the hollow structure spontaneously arising in the novel “close-edge” nanocages under the assistance of an ammonia cation bubble template. When evaluated as an anode material for lithium ion batteries, ex situ characterization indicates that these IF-MoS2 hollow nanocages can provide large expandable spaces for volume changes occurring during the cycles. Such a highly desired structure offers remarkably improved lithium storage performance including high reversible capacity and good cycling behavior and high rate capability.
256 citations
TL;DR: The synthesis of Pt-based icosahedral nanocages whose surface is enclosed by both {111} facets and twin boundaries while the wall thickness can be made as thin as six atomic layers is reported.
Abstract: Engineering the surface structure of noble-metal nanocrystals offers an effective route to the development of catalysts or electrocatalysts with greatly enhanced activity. Here, we report the synthesis of Pt-based icosahedral nanocages whose surface is enclosed by both {111} facets and twin boundaries while the wall thickness can be made as thin as six atomic layers. The nanocages are derived from Pd@Pt4.5L icosahedra by selectively etching away the Pd in the core. During etching, the multiply twinned structure can be fully retained whereas the Pt atoms in the wall reconstruct to eliminate the corrugated structure built in the original Pt shell. The Pt-based icosahedral nanocages show a specific activity of 3.50 mA cm(-2) toward the oxygen reduction reaction, much greater than those of the Pt-based octahedral nanocages (1.98 mA cm(-2)) and a state-of-the-art commercial Pt/C catalyst (0.35 mA cm(-2)). After 5000 cycles of accelerated durability test, the mass activity of the Pt-based icosahedral nanocages drops from 1.28 to 0.76 A mg(-1)Pt, which is still about four times greater than that of the original Pt/C catalyst (0.19 A mg(-1)Pt).
TL;DR: The structure and functions of ferritin nanocages are described, and an overview about the nanotechnological approaches implemented for applying them to cancer diagnosis and treatment is provided.
TL;DR: In this paper, the hierarchical hollow ZnO nanocages were synthesized by a facile strategy through the simple and direct pyrolysis of Zn-based metal-organic framework.
Abstract: The design and synthesis of nanostructured ZnO with high chemical sensing properties, especially towards ppb or sub-ppm level VOC gases is still highly desired and challengeable. Herein, the hierarchical hollow ZnO nanocages were synthesized by a facile strategy through the simple and direct pyrolysis of Zn-based metal-organic framework. The as-synthesized hollow ZnO products present the typical hierarchical structures with hollow interiors enveloped by interpenetrated ZnO nanoparticles as porous shell, providing structurally combined meso-/macro-porous channels for facilitating the diffusion and surface reaction of gas molecules. The gas-sensing experiments demonstrate that, in contrast with singular ZnO nanoparticles, the ZnO nanocages show significantly enhanced chemical sensing sensitivity and selectivity towards low-concentration volatile organic compounds, typically, acetone and benzene. Furthermore, the ZnO hollow nanocages perform sub-ppm level sensitivity with 2.3 ppm(-1) towards 0.1 ppm benzene, and ppb level sensitivity with 15.3 ppm(-1) towards 50 ppb acetone, respectively. The enhanced sensing performance of the MOF-derived ZnO nanocages is ascribed to the unique hierarchical structure with high specific surface area and abundant exposed active sites with surface-adsorbed oxygen. (C) 2015 Elsevier B.V. All rights reserved.
TL;DR: It is demonstrated that the CE based on inexpensive CoS2 embedded carbon nanocages is a prospective substitute to expensive platinum and provides a new approach for commercializing high-efficiency DSSCs.
Abstract: Owing to its excellent electrocatalytic properties, cobalt disulfide (CoS2) is regarded as a promising counter electrode (CE) material for dye-sensitized solar cells (DSSCs). However, hindered by its relatively poor electrical conductivity and chemical instability, it remains a challenge to apply it into high-performance DSSCs. In this work, we have developed novel CoS2 embedded carbon nanocages as a CE in DSSCs, using ZIF-67 (zeolitic imidazolate framework 67, Co(mim)2, mim = 2-methylimidolate) as a template. The CoS2 samples sulfurized for different time lengths are prepared through a facile solution process. It is found that the sulfurization time can be optimized to maximize the DSSC efficiency and the DSSC based on the CoS2 embedded carbon nanocages sulfurized for 4 hours exhibits the highest photovoltaic conversion efficiency (PCE) of 8.20%, higher than those of DSSCs consisting of other CoS2 CEs and Pt-based DSSC (7.88%). The significantly improved DSSC PCE is contributed by the synergic effect of inner CoS2 nanoparticles and an amorphous carbon matrix, leading to a CE with high catalytic activity, good electrical conductivity and excellent durability. This study demonstrates that the CE based on inexpensive CoS2 embedded carbon nanocages is a prospective substitute to expensive platinum and provides a new approach for commercializing high-efficiency DSSCs.
TL;DR: The designed synthesis of ZnO/ZnCo2O4 hollow core-shell nanocages (HCSNCs) through a metal-organic framework (MOF) route shows enhanced sensitivity to xylene and remarkable enhancement in the gas-sensing properties.
Abstract: The rational design of nanoscale metal oxides with hollow structures and tunable porosity has stimulated tremendous attention due to their vital importance for practical applications. Here, we report the designed synthesis of ZnO/ZnCo2O4 hollow core–shell nanocages (HCSNCs) through a metal–organic framework (MOF) route. The strategy includes the synthesis of a zeolite imidazolate framework-8 (ZIF-8)/Co–Zn hydroxide core–shell nanostructure precursor and subsequent transformation to ZnO/ZnCo2O4 HCSNCs by thermal annealing of the as-prepared precursor in air. Various techniques were employed for characterization of the structure and morphology of the as-prepared ZnO/ZnCo2O4 HCSNCs. When applied as a gas sensing material, the ZnO/ZnCo2O4 HCSNCs show enhanced sensitivity to xylene when compared with ZnCo2O4 shells as well as ZnO nanocages (NCs). In addition, excellent reversibility and superior selectivity of the sensor were observed. The remarkable enhancement in the gas-sensing properties of the ZnO/ZnCo2O4 HCSNCs is attributed to their unique structure and a synergistic effect of ZnO and ZnCo2O4.
TL;DR: The synthesis of Pt-Ag alloy nanocages with an outer edge length of 18 nm and a wall thickness of about 3 nm is reported, which could be readily prepared in one step through the galvanic replacement reaction between Ag nanocubes and a Pt(II) precursor.
Abstract: Engineering the elemental composition of metal nanocrystals offers an effective strategy for the development of catalysts or electrocatalysts with greatly enhanced activity. Herein, we report the synthesis of Pt–Ag alloy nanocages with an outer edge length of 18 nm and a wall thickness of about 3 nm. Such nanocages with a composition of Pt19Ag81 could be readily prepared in one step through the galvanic replacement reaction between Ag nanocubes and a Pt(II) precursor. After 10 000 cycles of potential cycling in the range of 0.60–1.0 V as in an accelerated durability test, the composition of the nanocages changed to Pt56Ag44, together with a specific activity of 1.23 mA cm–2 toward oxygen reduction, which was 3.3 times that of a state-of-the-art commercial Pt/C catalyst (0.37 mA cm–2) prior to durability testing. Density functional theory calculations attributed the increased activity to the stabilization of the transition state for breaking the O–O bond in molecular oxygen. Even after 30 000 cycles of pot...
TL;DR: A novel material of porous Co3O4/CuO hollow polyhedral nanocages (HPNCs) derived-from metal-organic frameworks (MOF) for photocatalytic water oxidation was reported for the first time and the molar ratio of Co/Cu in this kind material was optimized as discussed by the authors.
Abstract: A novel material of porous Co3O4/CuO hollow polyhedral nanocages (HPNCs) derived-from metal-organic frameworks (MOF) for photocatalytic water oxidation was reported for the first time and the molar ratio of Co/Cu in this kind material was optimized The Co3O4/CuO HPNCs composites were characterized by multiple experiments (FETEM, HRTEM, SEM, TGA, PXRD, EDX, ICP-AES, BET, XPS) to confirm the structure and the component A high turnover frequency (TOF) of 49 × 10−3 s−1 per metal atom was obtained over Co3O4/CuO-3 HPNCs, which is comparable to those published cobalt based catalysts At the same time, Co3O4/CuO-3 HPNCs showed a maximum oxygen yield of 50% and quantum yield of 49% This composite of Co3O4/CuO HPNCs containing heterojunctions may enhance the photocatalytic performance of water oxidationVarious characterization methods prove that Co3O4/CuO HPNCs composites are stable and robust heterogeneous photocatalytic catalysts that can be used repeatedly without any loss in activity According to the experimental results, we speculate that there are two kinds of reaction mechanisms in this light-driven water oxidation system One mechanism is widely accepted that high valence metal species play a role in the reaction system The other one is that the heterojunctions of Co3O4/CuO HPNCs make a great contribution to improve the activity of photocatalytic water oxidation Meanwhile, we put forward a new idea to design a series of metal oxide catalysts with heterojunctions derived from MOF for light-driven water oxidation
TL;DR: Computational simulations demonstrated that the hierarchical pore structure consisting of single-wall nanocages has suitable sizes/shapes and organic binding sites to enforce not only strong host- methane and methane-methane interactions but also dense packing of methane molecules.
Abstract: Much effort has been devoted to develop new porous structures for methane storage. We report a new porous coordination framework showing exceptional methane uptakes (e.g. 263 v/v at 298 K and 65 bar) and adsorption enthalpies (21.6 kJ mol−1) as high as current record holders functionalized by open metal sites. Computational simulations demonstrated that the hierarchical pore structure consisting of single-wall nanocages has suitable sizes/shapes and organic binding sites to enforce not only strong host–methane and methane–methane interactions but also dense packing of methane molecules.
TL;DR: An approach is developed to integrate dual plasmonic nanostructures with TiO2 semiconductor nanosheets for photocatalytic hydrogen production in visible and near-infrared spectral regions.
Abstract: Utilization of visible and near-infrared light has always been the pursuit of photocatalysis research. In this article, an approach is developed to integrate dual plasmonic nanostructures with TiO2 semiconductor nanosheets for photocatalytic hydrogen production in visible and near-infrared spectral regions. Specifically, the Au nanocubes and nanocages used in this work can harvest visible and near-infrared light, respectively, and generate and inject hot electrons into TiO2 . Meanwhile, Pd nanocubes that can trap the energetic electrons from TiO2 and efficiently participate in the hydrogen evolution reaction are employed as co-catalysts for improved catalytic activity. Enabled by this unique integration design, the hydrogen production rate achieved is dramatically higher than those of its counterpart structures. This work represents a step toward the rational design of semiconductor-metal hybrid structures for broad-spectrum photocatalysis.
TL;DR: In this paper, a reduced graphene oxide-Co3O4 yolk-shell nanocage (rGO-Co 3O4 YSNC) composite material is prepared through a facile precipitation reaction with subsequent calcination and hydrothermal treatment.
Abstract: The development of highly active, inexpensive and clean catalysts for applications in the oxygen evolution reaction (OER) is very important for energy storage and conversion. In this study, a reduced graphene oxide–Co3O4 yolk-shell nanocage (rGO–Co3O4 YSNC) composite material is prepared through a facile precipitation reaction with subsequent calcination and hydrothermal treatment. A strong chemical interaction formed between Co3O4 YSNCs and r-GO nanosheets is vital to produce a well wrapped composite material. This specific composite structure combines the high conductivity of r-GO together with the promising catalytic properties of the highly porous Co3O4 YSNCs, therefore the enhanced OER activity and stability is realized. The Tafel slope, current density at an overpotential of 450 mV and the overpotential at 10.0 mA cm−2 for the rGO–Co3O4 YSNC composite electrode are 84.9 mV dec−1, 19.9 mA cm−2 and 410 mV, respectively. Moreover, the composite electrode exhibits 2.8% attenuation of the current density after the 500th cyclic voltammetry test. These results are comparable to the currently reported high-performance OER catalysts, which prove that the rGO–Co3O4 YSNC composite material is a potential catalyst for oxygen evolution reactions.
TL;DR: In vitro and in vivo experiments show that PTPAuNC‐NPs can efficiently deliver anti‐miR‐181b into target sites to suppress tumor growth, and considerably decrease tumor volumes in SMMC‐7721 tumor‐bearing nude mice under near‐infrared radiation.
Abstract: Therapeutic strategies based on modulation of microRNAs (miRNAs) activity hold much promise for cancer therapy, but for clinical applications, the efficient delivery of miRNAs to tumor cells or tumor tissues remains a great challenge. In this work, microRNA-181b inhibitor (anti-miR-181b) is successfully condensed into polyethyleneimine (PEI)-modified and folate receptor (FR)-targeted PEGylated gold nanocages (AuNCs). This delivery system is designated as anti-miR-181b/PTPAuNCs nanocomplexes (PTPAuNC-NPs), which begin with chemical modification of AuNCs with SH-PEG5000-folic acid (SH-PEG5000-FA) and SH-PEG5000 through a gold–sulfur bond, followed by conjugating PEI using lipoic acid as a linker. Finally anti-miR-181b is condensed via electrostatic interactions. In vitro and in vivo experiments show that PTPAuNC-NPs can efficiently deliver anti-miR-181b into target sites to suppress tumor growth, and considerably decrease tumor volumes in SMMC-7721 tumor-bearing nude mice under near-infrared radiation. All these results suggest that PTPAuNC-NP gene delivery system with combination of gene therapy and photothermal therapy will be of great potential use in future cancer therapy.
TL;DR: Results show how proteins can be programmed to direct the formation of hybrid biological materials that perform complex tasks, and establish EPNs as a class of designed, modular, genetically-encoded nanomaterials that can transfer molecules between cells.
Abstract: Autonomously produced hybrid biological nanomaterials termed ‘enveloped protein nanocages’ incorporate features for membrane binding, self-assembly, and ESCRT recruitment for cellular release. Inspired by the process of enveloped virus assembly, Wesley Sundquist and colleagues have designed hybrid biomaterials termed 'enveloped protein nanocages' (EPNs), which incorporate features for membrane binding, self-assembly, and for the recruitment of the endosomal sorting complexes required for transport (ESCRT) machinery. The optimized EPN can be released as vesicles containing multiple nanocages, and the introduction of a viral glycoprotein allows them to fuse to target cells and deliver cargo. These autonomously produced hybrid biological nanomaterials can be modularly engineered for further applications. Complex biological processes are often performed by self-organizing nanostructures comprising multiple classes of macromolecules, such as ribosomes (proteins and RNA) or enveloped viruses (proteins, nucleic acids and lipids). Approaches have been developed for designing self-assembling structures consisting of either nucleic acids1,2 or proteins3,4,5, but strategies for engineering hybrid biological materials are only beginning to emerge6,7. Here we describe the design of self-assembling protein nanocages that direct their own release from human cells inside small vesicles in a manner that resembles some viruses. We refer to these hybrid biomaterials as ‘enveloped protein nanocages’ (EPNs). Robust EPN biogenesis requires protein sequence elements that encode three distinct functions: membrane binding, self-assembly, and recruitment of the endosomal sorting complexes required for transport (ESCRT) machinery8. A variety of synthetic proteins with these functional elements induce EPN biogenesis, highlighting the modularity and generality of the design strategy. Biochemical analyses and cryo-electron microscopy reveal that one design, EPN-01, comprises small (~100 nm) vesicles containing multiple protein nanocages that closely match the structure of the designed 60-subunit self-assembling scaffold9. EPNs that incorporate the vesicular stomatitis viral glycoprotein can fuse with target cells and deliver their contents, thereby transferring cargoes from one cell to another. These results show how proteins can be programmed to direct the formation of hybrid biological materials that perform complex tasks, and establish EPNs as a class of designed, modular, genetically-encoded nanomaterials that can transfer molecules between cells.
TL;DR: Self-consistent density functional theory calculations indicate that these unique fcc-structured Ru nanocages might possess promising catalytic properties for ammonia synthesis compared to hcp Ru(0001), on the basis of strengthened binding of atomic N and substantially reduced activation energies for N2 dissociation, which is the rate-determining step for ammonia synthesisation on hCP Ru catalysts.
Abstract: Nanocages have received considerable attention in recent years for catalytic applications owing to their high utilization efficiency of atoms and well-defined facets. Here we report, for the first time, the synthesis of Ru cubic nanocages with ultrathin walls, in which the atoms are crystallized in a face-centered cubic (fcc) rather than hexagonal close-packed (hcp) structure. The key to the success of this synthesis is to ensure layer-by-layer deposition of Ru atoms on the surface of Pd cubic seeds by controlling the reaction temperature and the injection rate of a Ru(III) precursor. By selectively etching away the Pd from the Pd@Ru core-shell nanocubes, we obtain Ru nanocages with an average wall thickness of 1.1 nm or about six atomic layers. Most importantly, the Ru nanocages adopt an fcc crystal structure rather than the hcp structure observed in bulk Ru. The synthesis has been successfully applied to Pd cubic seeds with different edge lengths in the range of 6-18 nm, with smaller seeds being more favorable for the formation of Ru shells with a flat, smooth surface due to shorter distance for the surface diffusion of the Ru adatoms. Self-consistent density functional theory calculations indicate that these unique fcc-structured Ru nanocages might possess promising catalytic properties for ammonia synthesis compared to hcp Ru(0001), on the basis of strengthened binding of atomic N and substantially reduced activation energies for N2 dissociation, which is the rate-determining step for ammonia synthesis on hcp Ru catalysts.
TL;DR: In this paper, a metal-organic framework (MOF) template-engaged strategy was used to synthesize MCTMPs with active noble metal free components with applications as sunlight-driven photocatalysts for hydrogen production through water splitting.
Abstract: Non-precious transition metal phosphides (TMPs) are emerging as the most promising substitutes for expensive noble metal-based co-catalysts for the hydrogen evolution reaction. While the synthesis of TMPs is well established, it is extremely challenging to design porous multicomponent transition metal phosphides (MCTMPs) to overcome the drawbacks of TMPs, namely, limited active sites and low surface area. Herein, we synthesized MCTMPs (containing Co, Ni, and Mo) from layered double hydroxide double-shelled nanocages by a metal–organic framework (MOF) template-engaged strategy. Benefiting from the rich structural features, high specific surface area, and multiple active components in the composition, the MCTMPs manifest greatly enhanced photocatalytic hydrogen evolution properties when integrated with CdS semiconductor nanorods. The observed hydrogen evolution rate is 53.76 fold higher than that of the bare CdS nanostructures and 4.37 times higher than that of the benchmark 2 wt% Pt–CdS nanorods, with a quantum efficiency of 40.6%. A possible explanation for the enhancement of the photocatalytic activity was proposed on the basis of the separation efficiency of the photogenerated charge carriers; this was further confirmed by photocurrent, electrochemical impedance spectroscopy, and photoluminescence studies. We believe that the work presented here represents a novel design strategy for MCTMPs with active noble metal free components with applications as sunlight-driven photocatalysts for hydrogen production through water splitting.
TL;DR: In this paper, the properties of doped boron nitride nanocages (MB 12 N 11 and MB 11 N 12 ) have been investigated theoretically, and it is revealed that first hyperpolarizability (β 0 ) is increased to a larger extent (1.3 ǫ× 10 4 au ) for KB 12 n 11 as compared to pure B 12 N 12 (0 au).
TL;DR: The shape-dependent anionic framework of Cu2O NCs determined the crystal system of anion-exchanged products of CuxS nanocages, which enabled us to convert a body- centered cubic lattice into either a face-centered cubic or a hexagonally close-packed lattice to form crystallographically unusual, multiply twinned structures.
Abstract: The crystal structure of ionic nanocrystals (NCs) is usually controlled through reaction temperature, according to their phase diagram. We show that when ionic NCs with different shapes, but identical crystal structures, were subjected to anion exchange reactions under ambient conditions, pseudomorphic products with different crystal systems were obtained. The shape-dependent anionic framework (surface anion sublattice and stacking pattern) of Cu2O NCs determined the crystal system of anion-exchanged products of CuxS nanocages. This method enabled us to convert a body-centered cubic lattice into either a face-centered cubic or a hexagonally close-packed lattice to form crystallographically unusual, multiply twinned structures. Subsequent cation exchange reactions produced CdS nanocages while preserving the multiply-twinned structures. A high-temperature stable phase such as wurtzite ZnS was also obtained with this method at ambient conditions.
TL;DR: In this article, the synthesis of the ultrasmall Pt-coated hollow graphene nanocages as cathode in Li-O2 batteries is reported, which can not only provide numerous nanoscale tri-phase regions as active sites for efficient oxygen reduction, but also offer sufficient amount of mesoscale pores for rapid oxygen diffusion.
Abstract: One of the formidable challenges facing aprotic lithium-oxygen (Li-O2) batteries is the high charge overpotential, which induces the formation of byproducts, loss in efficiency, and poor cycling performance. Herein, the synthesis of the ultrasmall Pt-coated hollow graphene nanocages as cathode in Li-O2 batteries is reported. The charge voltage plateau can reduce to 3.2 V at the current density of 100 mA g−1, even maintain below 3.5 V when the current density increased to 500 mA g−1. The unique hollow graphene nanocages matrix can not only provide numerous nanoscale tri-phase regions as active sites for efficient oxygen reduction, but also offer sufficient amount of mesoscale pores for rapid oxygen diffusion. Furthermore, with strong atomic-level oxygen absorption into its subsurface, ultrasmall Pt catalytically serves as the nucleation site for Li2O2 growth. The Li2O2 is subsequently induced into a favorable form with small size and amorphous state, decomposed more easily during recharge. Meanwhile, the conductive hollow graphene substrate can enhance the catalytic activity of noble metal Pt catalysts due to the graphene-metal interfacial interaction. Benefiting from the above synergistic effects between the hollow graphene nanocages and the nanosized Pt catalysts, the ultrasmall Pt-decorated graphene nanocage cathode exhibits enhanced electrochemical performances.
TL;DR: This is the first example of metal–organic framework (MOF)‐based catalysts in converting CO2 into high‐value oxazolidinones through activating aziridines and CO2, further extending the applications of MOFs materials in catalysis.
Abstract: Based on a novel ligand 5-(2,6-bis(4-carboxyphenyl)pyridin-4-yl)isophthalic acid (H4BCP) with large skeletons, a unique porous framework {[Cu2(BCP)(H2O)2]·3DMF} n (1) assembled by nano-sized and censer-like [Cu30] cages is successfully obtained and structurally characterized. In 1, the large 1D channel in frameworks and window size in the nanocages can enrich methylene blue and capture CO2, exhibiting the promising applications in environmental protection. More importantly, the explorations on the cycloaddition reaction of CO2 and aziridines with various substituents suggest that 1 can serve as an efficient heterogeneous catalyst for CO2 conversion with aziridines in a solvent-free system, which can be reused at least ten times without any obvious loss in catalytic activity. This is the first example of metal-organic framework (MOF)-based catalysts in converting CO2 into high-value oxazolidinones through activating aziridines and CO2, further extending the applications of MOFs materials in catalysis.
TL;DR: The series of MOFs FJU-14 are demonstrated as the first examples of the isostructural MOFs whose robustness, thermal stability, and CO2 capacity can be greatly improved via rational modulation of counteranions in the tetrahedral cages.
Abstract: Microporous metal organic frameworks (MOFs) show promising application in several fields, but they often suffer from the weak robustness and stability after the removal of guest molecules. Here, three isostructural cationic metal–organic frameworks {[(Cu4Cl)(cpt)4(H2O)4]·3X·4DMAc·CH3OH·5H2O} (FJU-14, X = NO3, ClO4, BF4; DMAc = N,N′-dimethylacetamide) containing two types of polyhedral nanocages, one octahedron, and another tetrahedron have been synthesized from bifunctional organic ligands 4-(4H-1,2,4-triazol-4-yl) benzoic acid (Hcpt) and various copper salts. The series of MOFs FJU-14 are demonstrated as the first examples of the isostructural MOFs whose robustness, thermal stability, and CO2 capacity can be greatly improved via rational modulation of counteranions in the tetrahedral cages. The activated FJU-14-BF4-a containing BF4– anion can take CO2 of 95.8 cm3 cm–3 at ambient conditions with an adsorption enthalpy only of 18.8 kJ mol–1. The trapped CO2 density of 0.955 g cm–3 is the highest value amon...