Aerosol route to functional nanostructured inorganic and hybrid porous materials

Facile Synthesis of Novel Networked Ultralong Cobalt Sulfide Nanotubes and Its Application in Supercapacitors

Ultralong cobalt sulfide (CoS(1.097)) nanotube networks are synthesized by a simple one-step solvothermal method without any surfactant or template. A possible formation mechanism for the growth processes is proposed. Owing to the hollow structure and large specific area, the novel CoS(1.097) materials present outstanding electrochemical properties. Electrochemical measurements for supercapacitors show that the as-prepared ultralong CoS(1.097) nanotube networks exhibit high specific capacity, good capacity retention, and excellent Coulombic efficiency.

Smart Mesoporous Nanomaterials for Antitumor Therapy

The use of nanomaterials for the treatment of solid tumours is receiving increasing attention by the scientific community. Among them, mesoporous silica nanoparticles (MSNs) exhibit unique features that make them suitable nanocarriers to host, transport and protect drug molecules until the target is reached. It is possible to incorporate different targeting ligands to the outermost surface of MSNs to selectively drive the drugs to the tumour tissues. To prevent the premature release of the cargo entrapped in the mesopores, it is feasible to cap the pore entrances using stimuli-responsive nanogates. Therefore, upon exposure to internal (pH, enzymes, glutathione, etc.) or external (temperature, light, magnetic field, etc.) stimuli, the pore opening takes place and the release of the entrapped cargo occurs. These smart MSNs are capable of selectively reaching and accumulating at the target tissue and releasing the entrapped drug in a specific and controlled fashion, constituting a promising alternative to conventional chemotherapy, which is typically associated with undesired side effects. In this review, we overview the recent advances reported by the scientific community in developing MSNs for antitumor therapy. We highlight the possibility to design multifunctional nanosystems using different therapeutic approaches aimed at increasing the efficacy of the antitumor treatment.

Toward industrial scale synthesis of ultrapure singlet nanoparticles with controllable sizes in a continuous gas-phase process

Continuous gas-phase synthesis of nanoparticles is associated with rapid agglomeration, which can be a limiting factor for numerous applications. In this report, we challenge this paradigm by providing experimental evidence to support that gas-phase methods can be used to produce ultrapure non-agglomerated “singlet” nanoparticles having tunable sizes at room temperature. By controlling the temperature in the particle growth zone to guarantee complete coalescence of colliding entities, the size of singlets in principle can be regulated from that of single atoms to any desired value. We assess our results in the context of a simple analytical model to explore the dependence of singlet size on the operating conditions. Agreement of the model with experimental measurements shows that these methods can be effectively used for producing singlets that can be processed further by many alternative approaches. Combined with the capabilities of up-scaling and unlimited mixing that spark ablation enables, this study provides an easy-to-use concept for producing the key building blocks for low-cost industrial-scale nanofabrication of advanced materials.

Spray-Dried Multiscale Nano-biocomposites Containing Living Cells

Three-dimensional encapsulation of cells within nanostructured silica gels or matrices enables applications as diverse as biosensors, microbial fuel cells, artificial organs, and vaccines; it also allows the study of individual cell behaviors. Recent progress has improved the performance and flexibility of cellular encapsulation, yet there remains a need for robust scalable processes. Here, we report a spray-drying process enabling the large-scale production of functional nano-biocomposites (NBCs) containing living cells within ordered 3D lipid-silica nanostructures. The spray-drying process is demonstrated to work with multiple cell types and results in dry powders exhibiting a unique combination of properties including highly ordered 3D nanostructure, extended lipid fluidity, tunable macromorphologies and aerodynamic diameters, and unexpectedly high physical strength. Nanoindentation of the encasing nanostructure revealed a Young's modulus and hardness of 13 and 1.4 GPa, respectively. We hypothesized this high strength would prevent cell growth and force bacteria into viable but not culturable (VBNC) states. In concordance with the VBNC state, cellular ATP levels remained elevated even over eight months. However, their ability to undergo resuscitation and enter growth phase greatly decreased with time in the VBNC state. A quantitative method of determining resuscitation frequencies was developed and showed that, after 36 weeks in a NBC-induced VBNC, less than 1 in 10,000 cells underwent resuscitation. The NBC platform production of large quantities of VBNC cells is of interest for research in bacterial persistence and screening of drugs targeting such cells. NBCs may also enable long-term preservation of living cells for applications in cell-based sensing and the packaging and delivery of live-cell vaccines.

Nanohole-Structured and Palladium-Embedded 3D Porous Graphene for Ultrahigh Hydrogen Storage and CO Oxidation Multifunctionalities

Atomic-scale defects on carbon nanostructures have been considered as detrimental factors and critical problems to be eliminated in order to fully utilize their intrinsic material properties such as ultrahigh mechanical stiffness and electrical conductivity. However, defects that can be intentionally controlled through chemical and physical treatments are reasonably expected to bring benefits in various practical engineering applications such as desalination thin membranes, photochemical catalysts, and energy storage materials. Herein, we report a defect-engineered self-assembly procedure to produce a three-dimensionally nanohole-structured and palladium-embedded porous graphene hetero-nanostructure having ultrahigh hydrogen storage and CO oxidation multifunctionalities. Under multistep microwave reactions, agglomerated palladium nanoparticles having diameters of ∼10 nm produce physical nanoholes in the basal-plane structure of graphene sheets, while much smaller palladium nanoparticles are readily impregnated inside graphene layers and bonded on graphene surfaces. The present results show that the defect-engineered hetero-nanostructure has a ∼5.4 wt % hydrogen storage capacity under 7.5 MPa and CO oxidation catalytic activity at 190 °C. The defect-laden graphene can be highly functionalized for multipurpose applications such as molecule absorption, electrochemical energy storage, and catalytic activity, resulting in a pathway to nanoengineering based on underlying atomic scale and physical defects.

Aerosol-Assisted Heteroassembly of Oxide Nanocrystals and Carbon Nanotubes into 3D Mesoporous Composites for High-Rate Electrochemical Energy Storage

Nanostructured composites built from ordinary building units have attracted much attention because of their collective properties for critical applications. Herein, we have demonstrated the heteroassembly of carbon nanotubes and oxide nanocrystals using an aerosol spray method to prepare nanostructured mesoporous composites for electrochemical energy storage. The designed composite architectures show high conductivity and hierarchically structured mesopores, which achieve rapid electron and ion transport in electrodes. Therefore, as-synthesized carbon nanotube/TiO2 electrodes exhibit high rate performance through rapid Li(+) intercalation, making them suitable for ultrafast energy storage devices. Moreover, the synthesis process provides a broadly applicable method to achieve the heteroassembly of vast low-dimensional building blocks for many important applications.

Activation of the Solid Silica Layer of Aerosol-Based C/SiO₂ Particles for Preparation of Various Functional Multishelled Hollow Microspheres

Double-shelled C/SiO2 hollow microspheres with an outer nanosheet-like silica shell and an inner carbon shell were reported. C/SiO2 aerosol particles were synthesized first by a one-step rapid aerosol process. Then the solid silica layer of the aerosol particles was dissolved and regrown on the carbon surface to obtain novel C/SiO2 double-shelled hollow microspheres. The new microspheres prepared by the facile approach possess high surface area and pore volume (226.3 m(2) g(-1), 0.51 cm(3) g(-1)) compared with the original aerosol particles (64.3 m(2) g(-1), 0.176 cm(3) g(-1)), providing its enhanced enzyme loading capacity. The nanosheet-like silica shell of the hollow microspheres favors the fixation of Au NPs (C/SiO2/Au) and prevents them from growing and migrating at 500 °C. Novel C/C and C/Au/C (C/Pt/C) hollow microspheres were also prepared based on the hollow nanostructure. C/C microspheres (482.0 m(2) g(-1), 0.92 cm(3) g(-1)) were ideal electrode materials. In particular, the Au NPs embedded into the two carbon layers (C/Au/C, 431.2 m(2) g(-1), 0.774 cm(3) g(-1)) show a high catalytic activity and extremely chemical stability even at 850 °C. Moreover, C/SiO2/Au, C/Au/C microspheres can be easily recycled and reused by an external magnetic field because of the presence of Fe3O4 species in the inner carbon shell. The synthetic route reported here is expected to simplify the fabrication process of double-shelled or yolk-shell microspheres, which usually entails multiple steps and a previously synthesized hard template. Such a capability can facilitate the preparation of various functional hollow microspheres by interfacial design.

Ultrasonic-spray-assisted synthesis of metal oxide hollow/mesoporous microspheres for catalytic CO oxidation

Various transition metal oxide hollow or mesoporous microspheres with improved catalytic activities towards CO oxidation were prepared via a general ultrasonic-spray-assisted method.

Facile and green aerosol-assisted synthesis of zeolites

A facile and green aerosol-assisted method was proposed to synthesize various zeolites.

Green and low-cost synthesis of PANI–TiO2 nanocomposite mesoporous films for photoelectrochemical water splitting

Green and low-cost synthesis procedure for preparation of PANI/TiO₂ mesoporous nanocomposite films with enhanced photocatalytic performance, thanks to a synergic reaction mechanism between PANI and TiO₂ under UV light irradiation.

Improved silica–titania catalysts by chitin biotemplating

New silica–titania mesoporous catalysts with improved performance were achieved by combining surface and templating properties of α-chitin nanorods recovered from biomass with sol–gel and spray-drying processes.

Preparation of porous carbon microspheres anode materials from fine needle coke powders for lithium-ion batteries

Fine carbon particles are granulated to porous carbon microspheres which show improved electrochemical properties as anode materials for lithium ion batteries.

Au encapsulated into Al-MCM-41 mesoporous material: in situ synthesis and electronic structure

A facile one-step technique is proposed for the successful synthesis of highly ordered Au/Al-MCM-41. The charge state of Au³⁺ in the mesoporous framework was partially reduced due to the accompanying Al when clay was used as source.

First acidic macro-mesocellular aluminosilicate monolithic foams “SiAl(HIPE)” and their catalytic properties

A new type of macrocellular and mesoporous acidic aluminosilicate monolithic foam obtained by a templated alkaline sol–gel route exhibits high dehydration activity.

An electrochemistry assisted approach for fast, low-cost and gram-scale synthesis of mesoporous silica nanoparticles

Gram-scale mesoporous silica nanoparticles (MSNs) were prepared by a facile electrochemistry assisted sol–gel approach.

Aerodynamically focused nanoparticle (AFN) printing: novel direct printing technique of solvent-free and inorganic nanoparticles

Aerodynamically focused nanoparticle (AFN) printing was demonstrated for direct patterning of the solvent-free and inorganic nanoparticles. The fast excitation-purge control technique was proposed and investigated by examining the aerodynamic focusing of nanoparticles and their time-scale, with the analytical and experimental approaches. A series of direct patterning examples were demonstrated with Barium Titanate (BaTiO3) and Silver (Ag) nanoparticles onto the flexible and inflexible substrates using the AFN printing system. The capacitor and flexible conductive line pattern were fabricated as the application examples of the proposed technique. The results presented here should contribute to the nanoparticle manipulation, patterning, and their applications, which are intensely being studied nowadays.

Aerosol synthesis of self-organized nanostructured hollow and porous carbon particles using a dual polymer system

A facile method for designing and synthesizing nanostructured carbon particles via ultrasonic spray pyrolysis of a self-organized dual polymer system comprising phenolic resin and charged polystyrene latex is reported. The method produces either hollow carbon particles, whose CO2 adsorption capacity is 3.0 mmol g(-1), or porous carbon particles whose CO2 adsorption capacity is 4.8 mmol g(-1), although the two particle types had similar diameters of about 360 nm. We investigate how the zeta potential of the polystyrene latex particles, and the resulting electrostatic interaction with the negatively charged phenolic resin, influences the particle morphology, pore structure, and CO2 adsorption capacity.

Building robust carbon nanotube-interweaved-nanocrystal architecture for high-performance anode materials

Rational design of electrode materials is essential but still a challenge for lithium-ion batteries. Herein, we report the design and fabrication of a class of nanocomposite architecture featured by hierarchically structured composite particles that are built from iron oxide nanocrystals and carbon nanotubes. An aerosol spray drying process was used to synthesize this architecture. Such nanoarchitecture enhanced the ion transport and conductivity that are required for high-power anodes. The large volume changes of the anodes during lithium insertion and extraction are accommodated by the particle's resilience and internal porosity. High reversible capacities, excellent rate capability, and stable performance are attained. The synthesis process is simple and broadly applicable, providing a general approach toward high-performance energy storage materials.

Hybrid materials science: a promised land for the integrative design of multifunctional materials

For more than 5000 years, organic-inorganic composite materials created by men via skill and serendipity have been part of human culture and customs. The concept of "hybrid organic-inorganic" nanocomposites exploded in the second half of the 20th century with the expansion of the so-called "chimie douce" which led to many collaborations between a large set of chemists, physicists and biologists. Consequently, the scientific melting pot of these very different scientific communities created a new pluridisciplinary school of thought. Today, the tremendous effort of basic research performed in the last twenty years allows tailor-made multifunctional hybrid materials with perfect control over composition, structure and shape. Some of these hybrid materials have already entered the industrial market. Many tailor-made multiscale hybrids are increasingly impacting numerous fields of applications: optics, catalysis, energy, environment, nanomedicine, etc. In the present feature article, we emphasize several fundamental and applied aspects of the hybrid materials field: bioreplication, mesostructured thin films, Lego-like chemistry designed hybrid nanocomposites, and advanced hybrid materials for energy. Finally, a few commercial applications of hybrid materials will be presented.

Hollow-structured mesoporous materials: chemical synthesis, functionalization and applications

Hollow-structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft-templating and hard-templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented.

Introduction of bifunctional groups into mesoporous silica for enhancing uptake of thorium(IV) from aqueous solution

The potential industrial application of thorium (Th), as well as the environmental and human healthy problems caused by thorium, promotes the development of reliable methods for the separation and removal of Th(IV) from environmental and geological samples. Herein, the phosphonate-amino bifunctionalized mesoporous silica (PAMS) was fabricated by a one-step self-assembly approach for enhancing Th(IV) uptake from aqueous solution. The synthesized sorbent was found to possess ordered mesoporous structures with uniform pore diameter and large surface area, characterized by SEM, XRD, and N2 sorption/desorption measurements. The enhancement of Th(IV) uptake by PAMS was achieved by coupling of an access mechanism to a complexation mechanism, and the sorption can be optimized by adjusting the coverage of the functional groups in the PAMS sorbent. The systemic study on Th(IV) sorption/desorption by using one coverage of PAMS (PAMS12) shows that the Th(IV) sorption by PAMS is fast with equilibrium time of less than 1 h, and the sorption capacity is more than 160 mg/g at a relatively low pH. The sorption isotherm has been successfully modeled by the Langmuir isotherm and D-R isotherm, which reveals a monolayer homogeneous chemisorption of Th(IV) in PAMS. The Th(IV) sorption by PAMS is pH dependent but ionic strength independent. In addition, the sorbed Th(IV) can be completely desorbed using 0.2 mol/L or more concentrated nitric acid solution. The sorption test performed in the solution containing a range of competing metal ions suggests that the PAMS sorbent has a desirable selectivity for Th(IV) ions.

Aerosol-based fabrication of modified chitosans and their application for gene transfection

Modified chitosan nanoparticles were conveniently obtained by a one-step aerosol method, and their potential for gene transfection was investigated. Droplets containing modified chitosans were formed by collison atomization, dried to form solid particles, and collected and studied for potential use as nanocarriers. Modified chitosans consisted of a chitosan backbone and an additional component [covalently attached cholesterol; or blends with poly(l-lysine) (PLL), polyethyleneimine (PEI), or poly(ethylene glycol) (PEG)]. Agarose gel retardation assays confirmed that modified chitosans could associate with plasmid DNA. Even though the average cell viability of cholesterol-chitosan (Ch-Cs) showed a slightly higher cytotoxicity (∼90% viability) than that for unmodified chitosan (Cs, ∼95%), transfection (>7.5 × 10(5) in relative light units (RLU) mg(-1)) was more effective than it was for Cs (∼7.6 × 10(4) RLU mg(-1)). The blending of PEI with Cs (i.e., a Cs/PEI) to produce transfection complexes enhanced the transfection efficiency (∼1.3 × 10(6) RLU mg(-1)) more than did the addition of PLL (i.e., a Cs/PLL, ∼9.3 × 10(5) RLU mg(-1)); however, it also resulted in higher cytotoxicity (∼86% viability for Cs/PEI vs ∼94% for Cs/PLL). The average cell viability (∼92%) and transfection efficiency (∼1.9 × 10(6) RLU mg(-1)) were complemented further by addition of PEG in Cs/PEI complexes (i.e., a Cs/PEI-PEG). This work concludes that gene transfection of Cs can be significantly enhanced by adding cationic polymers during aerosol fabrication without wet chemical modification processes of Cs.

Pitaya-like Sn@C nanocomposites as high-rate and long-life anode for lithium-ion batteries

In this article, we report on the preparation of the pitaya-like Sn@C nanocomposite with an aerosol spray pyrolysis and its application as a high-rate and long-life anode material for lithium-ion batteries. The structure and morphology analysis of the as-prepared Sn@C nanocomposite shows that Sn nanoparticles with a size of about 8 nm are homogeneously dispersed in the spherical carbon matrix (denoted as Sn8@C). The Sn8@C nanocomposite exhibits an initial discharge capacity of 1007.1 mA h g(-1) and maintains a reversible capacity of 910 mA h g(-1) after 180 cycles at 200 mA g(-1) (0.305 C). A capacity of 410 mA h g(-1) was obtained after 1000 cycles at 4000 mA g(-1) (6.1 C). Furthermore, the Sn8@C nanocomposite displays a charge-discharge capacity of 205.3 mA h g(-1) at 16 000 mA g(-1) (24.4 C). This high-rate performance is owing to the fact that the ultrasmall tin nanoparticles can effectively alleviate the absolute stress/strain during the lithiation/delithiation process and that the uniformly embedded nanoparticles in the stable carbon framework can accommodate the large volume change with a buffering effect to prevent Sn nanoparticles from aggregating.

Porous graphene materials for advanced electrochemical energy storage and conversion devices

Combining the advantages from both porous materials and graphene, porous graphene materials have attracted vast interests due to their large surface areas, unique porous structures, diversified compositions and excellent electronic conductivity. These unordinary features enable porous graphene materials to serve as key components in high-performance electrochemical energy storage and conversion devices such as lithium ion batteries, supercapacitors, and fuel cells. This progress report summarizes the typical fabrication methods for porous graphene materials with micro-, meso-, and macro-porous structures. The structure-property relationships of these materials and their application in advanced electrochemical devices are also discussed.

Water-medium organic synthesis over active and reusable organometal catalysts with tunable nanostructures

Robust and reusable heterogeneous organometal catalysts open a new avenue to green chemical synthesis in water.

Thermoseeds for interstitial magnetic hyperthermia: from bioceramics to nanoparticles

The development of magnetic materials for interstitial hyperthermia treatment of cancer is an ever evolving research field which provides new alternatives to antitumoral therapies. The development of biocompatible magnetic materials has resulted in new biomaterials with multifunctional properties, which are able to adapt to the complex scenario of tumoral processes. Once implanted or injected in the body, magnetic materials can behave as thermoseeds under the effect of AC magnetic fields. Magnetic bioceramics aimed to treat bone tumors and magnetic nanoparticles are among the most studied thermoseeds, and supply different solutions for the different scenarios in cancerous processes. This paper reviews some of the biomaterials used for bone cancer treatment and skeletal reinforcing, as well as the more complex topic of magnetic nanoparticles for intracellular targeting and hyperthermia.

Simultaneous microfabrication and tuning of the permselective properties in microporous polymers using X-ray lithography

Microchannels are fabricated using a photosensitive polymer to which microporosity is tuned with different X-ray doses. Using hard X-ray irradiation, the micropattern is positioned with various geometries in a multi-level, three-dimensional structure, while controlling the pore size and transport properties of small molecules. This highly reliable fabrication process has potential for use in microfluidic devices with enhanced transport properties through microchannels.

Maneuvering the internal porosity and surface morphology of electrospun polystyrene yarns by controlling the solvent and relative humidity

This article presents a simple and reliable method for generating polystyrene (PS) yarns composed of bundles of nanofibrils by using a proper combination of solvent and relative humidity. We elucidated the mechanism responsible for the formation of this new morphology by systematically investigating the molecular interactions among the polymer, solvent(s), and water vapor. We demonstrated that vapor-induced phase separation played a pivotal role in generating the yarns with a unique structure. Furthermore, we discovered that the low vapor pressure of N,N-dimethylformamide (DMF) was critical to the evolution of pores in the interiors. On the contrary, the relatively high vapor pressure of tetrahydrofuran (THF) hindered the formation of interior pores but excelled in creating a rough surface. In all cases, our results clearly indicate that the formation of either internal porosity or surface roughness required the presence of water vapor, a nonsolvent of the polymer, at a proper level of relative humidity. The exact morphology or pore structure was dependent on the speed of evaporation of the solvent(s) (DMF, THF, and their mixtures) as well as the interdiffusion and penetration of the nonsolvent (water) and solvent(s). Our findings can serve as guidelines for the preparation of fibers with desired porosity both internally and externally through electrospinning.