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Thermoplastic elastomers (TPEs) are nanostructured, melt‐processable, elastomeric block copolymers. When TPEs that form cylindrical or lamellar nanostructures are macroscopically oriented, their material properties can exhibit several orders of magnitude of anisotropy. Here it is demonstrated that the flows applied during the 3D printing of a cylinder‐forming TPE enable hierarchical control over material nanostructure and function. It is demonstrated that 3D printing allows for control over the extent of nanostructural and mechanical anisotropy and that thermal annealing of 3D printed structures leads to highly anisotropic properties (up to 85 × anisotropic tensile modulus). This approach is leveraged to print functional soft 3D architectures with tunable local and macroscopic mechanical responses. Further, these printed TPEs intrinsically achieve melt‐reprocessability over multiple cycles, reprogrammability, and robust self‐healing via a brief period of thermal annealing, enabling facile fabrication of highly tunable, robust, and recyclable soft architectures. [ABSTRACT FROM AUTHOR]

Cobalt‐based sulfide is an excellent electrode material applied to supercapacitors (SCs) because of its good reversibility and abundant nanoforms. However, the feasibility of its practical application is reduced due to lack of stability and some difference with theoretical capacity. Herein, the hierarchical structures of Co3S4 hollow nanotube arrays wrapped with NiCo‐layered double hydroxide nanosheets (Co3S4@NiCo‐LDHs) are successfully fabricated on the nickel foam (NF) as the nonbinder electrode of SCs. Profiting from the synthetic effect of Co3S4 hollow nanotube arrays with effective diffusion channels, and NiCo‐LDH nanosheets with a stable interconnected network, the prepared Co3S4@NiCo‐LDH/NF composite electrode with a unique hierarchical structure attains an amazing areal capacity (7.45 C cm−2 at 2 mA cm−2) and impressive cycle stability (87.7% through 5000 charge and discharge cycles). In addition, the assembled asymmetric supercapacitor (Co3S4@NiCo‐LDH/NF//AC) shows pleasant energy density (0.661 mWh cm−2 under 1.359 mW cm−2). The capacity of the assembled device can still be retained at 92% after 5000 cycles, which verifies the feasibility of the device in practical application. [ABSTRACT FROM AUTHOR]

Microsupercapacitors have picked up a remarkable reputation as prospective micropower sources for compact electronics. Unfortunately, the fabricating complexity of electrode structures and preparing sophistication of electrode materials have prevented their practical deployment. Herein, a one‐step low‐temperature precipitation method is applied to straightforwardly self‐assemble porous Ni(OH)2 nanosheets on the surface of carbon nanotubes (CNTs) surface beneath electrostatic interaction. The developed core–shell 1D CNTs@Ni(OH)2 nanosheets nanostructures exhibit high electron and ion conductivity, a sign of excellent energy storage capability. In this vein, a thermally assisted 3D printing process is intelligently regulated to enable the fabrication of 3D interdigital electrodes from as‐obtained materials. The ultimate solid‐state microsupercapacitors of CNTs@Ni(OH)2 nanosheets core–shell nanostructures in this way exhibit excellent cycle stability and offer an exceptional areal capacitance of 39.6 mF cm−2, approximately a size of or two higher than that of C‐based partners. A strong foundation for high‐quality microsupercapacitors is laid by the high specific capacity of CNTs@Ni(OH)2 nanosheets core–shell nanostructures and the ability to fabricate 3D interdigital electrodes using a thermally assisted 3D printing process. [ABSTRACT FROM AUTHOR]

The properties of materials play a significant role in triboelectric nanogenerators (TENGs). Advanced triboelectric materials for TENGs have attracted tremendous attention because of their superior advantages (e.g., high specific surface area, high porosity, and customizable macrostructure). These advanced materials can be extensively applied in numerous fields, including energy harvester, wearable electronics, filtration, and self‐powered sensors. Hence, designing triboelectric materials as advanced functional materials is important for the development of TENGs. Herein, the structural modification methods based on electrospinning to improve the triboelectric properties and the latest research progress in this kind of TENGs are systematically summarized. Preparation methods and design trends of nanofibers, microspheres, hierarchical structures, and doping nanomaterials are highlighted. The factors influencing the formation and properties of triboelectric materials are considered. Furthermore, the latest progress on the applications of TENGs is systematically elaborated. Finally, the challenges in the development of triboelectric materials are discussed, thereby guiding researchers in the large‐scale application of TENGs. [ABSTRACT FROM AUTHOR]

The serious shuttle effect, sluggish reduction kinetics of polysulfides and the difficult oxidation reaction of Li2S have hindered LiS battery practical application. Herein, a 3D hierarchical structure composed of NiMoO4 nanosheets in situ anchored on NS doped carbon clothes (NiMoO4@NSCC) as the free‐standing host is creatively designed and constructed for LiS battery. Dual transitional metal oxide (NiMoO4) increases the electrons density near the Fermi level due to the contribution of the incorporating molybdenum (Mo), leading to the smaller bandgap, and thus stronger metallic properties compared with NiO. Furthermore, as a bidirectional catalyst, NiMoO4 is proposed to facilitate reductions of polysulfides through lengthening the SS bond distance of Li2S4 and reducing the free energy of polysulfides conversion, meanwhile promote critical oxidation of insulative discharge product (Li2S) via lengthening LiS bond distance of Li2S and decreasing Li2S decomposition barrier. Therefore, after loading sulfur (2 mg cm−2), NiMoO4@NSCC/S as the self‐supporting cathode for the LiS battery exhibits impressive long cycle stability. This study proposes a concept of a bidirectional catalyst with dual metal oxides, which would supply a novel vision to construct the high‐performance LiS battery. [ABSTRACT FROM AUTHOR]

For advanced fibrosis, isoprene is a typical characteristic marker that could be used to quickly screen the population for chronic liver disease (CLD). To achieve trace detection of isoprene, different mol% Pt-decorated In 2 O 3 and pure In 2 O 3 samples were prepared with the commonly used hydrothermal method. The obtained characterization results show that the prepared Pt-decorated In 2 O 3 (1 mol%) sample had Pt nanoparticles uniformly attached to the surface of porous hierarchical In 2 O 3 nanosheets, and the specific surface area was 62.3 m2/g. Subsequently, these sensors based on Pt–In 2 O 3 and pure In 2 O 3 nanomaterials were prepared, and their response characteristics were studied. The results show that the response of 1 mol% Pt–In 2 O 3 to isoprene gas was significantly enhanced, and the optimal working temperature was 200 °C. The response of 1 mol% Pt–In 2 O 3 to 5 ppb and 5 ppm isoprene was approximately 3.2 times and 25.9 times that of pure In 2 O 3 , respectively. Meanwhile, the 1 mol% Pt-modified sample exhibited excellent selectivity for isoprene relative to other biomarkers (carbon monoxide, hydrogen, ethanol, and ammonia). The sensor shows good repeatability and long-term stability. Therefore, the developed 1 mol% Pt-decorated In 2 O 3 was expected to be applied as a gas-sensitive material for breath isoprene, which could be suitable for large-scale CLD rapid breath detection. [ABSTRACT FROM AUTHOR]

Graphene‐based aerogels have been widely studied for their high porosity, good compressibility, and electrical conductivity as piezoresistive sensors. However, the fabrication of graphene aerogel sensors with good mechanical properties and excellent sensing properties simultaneously remains a challenge. Therefore, in this study, a novel nanofiber reinforced graphene aerogel (aPANF/GA) which has a 3D interconnected hierarchical microstructure with surface‐treated PAN nanofiber as a support scaffold throughout the entire graphene network is designed. This 3D interconnected microporous aPANF/GA aerogel combines an excellent compressive stress of 43.50 kPa and a high piezoresistive sensitivity of 28.62 kPa−1 as well as a wide range (0–14 kPa) linear sensitivity. When aPANF/GA is used as a piezoresistive sensor, the compression resilience is excellent, the response time is fast at about 37 ms at 3 Pa, and the structural stability and sensing durability are good after 2600 cycles. Indeed, the current signal value is 91.57% of the initial signal value at 20% compressive strain. Furthermore, the assembled sensors can monitor the real time movement of throat, wrist pulse, fingers, wrist, and knee joints of the human body at good sensitivity. These excellent features enable potential applications in health detection. [ABSTRACT FROM AUTHOR]

Highlights • A simplified not-expensive method for superhydrophobic coatings was developed. • The coatings has contact angle up to 154° instead of 73° of the reference. • The coating resists to flight conditions. • The coating can be applied to opaque and transparent, rough and smooth substrates. • The coating modifies both the chemistry and the morphology of the surface. Abstract The deposition of ice on wings and tails surfaces of aircrafts often alters the airflow reducing the lift force and causing aerodynamic stall. In order to prevent these kind of serious problems, de-icing and anti-icing systems, which act by removing the ice once it has formed, and by preventing its formation, respectively, are usually employed. In particular, the anti-icing superhydrophobic and icephobic coatings can be achieved by designing and realizing nanostructured surfaces by taking inspiration from effective surface present in nature, e.g., the lotus leaf. However, this process is often expensive and requires specialized equipment. The effort of the present work is to find out a simplified and not-expensive method to prepare superhydrophobic coatings to be applied on large aircraft surfaces. Among the investigated methods, the deposition of several layers of a homogeneous hydrophobic silica nanoparticles by using a simple aerograph allowed to build-up a coating which exhibits a contact angle of 154°. The coating withstands to aging tests simulating flight conditions. Also during typical flight conditions, i.e., −12 °C and 0.5 bar, it retains its hierarchical superficial morphology with roughness features from nano- to micro-scale and shows contact angle higher than the commercial reference. [ABSTRACT FROM AUTHOR]

The preparation of a hierarchically assembled Ag nanostructures based on a nanocrystalline assembly was demonstrated using an Ag(I) complex of a dipeptide (AspDap). By heating under N2 gas, a spherical assembly of a nanocrystalline dipeptide‐Ag(I) complex (diameter 4–5 μm), which has a morphology similar to the assembled structure of the dipeptide, was transformed to an assembly of Ag nanostructures, where the micrometre‐order crystalline morphology was maintained. In addition, detailed scanning electron microscopy studies revealed that Ag nanoparticles (diameter ca. 10 nm) were formed on the surface of the Ag nanostructure. When the Ag(I) ions were reduced to Ag(0), this phenomenon exhibited surface dependence due to the anisotropic two‐dimensional Ag(I) arrangement in the crystals. Thermogravimetric measurements and X‐ray photoelectron spectroscopy revealed that the reduction proceeds in a stepwise manner around 200–250 °C, together with the removal of primary and secondary carboxylic groups in the dipeptide. Comparison with the heating process of the crystalline Ag(I) complex of β‐alanine indicated that stepwise reduction is key for maintaining the original micrometre‐order morphology. A silver lining: The preparation of hierarchically assembled Ag nanostructures based on a nanocrystalline assembly was demonstrated using a Ag(I) complex of a dipeptide (AspDap). Stepwise reductions of the Ag(I) centre and protection by amino residues, which both result from the dipeptide, are key for maintaining the original crystalline morphology. [ABSTRACT FROM AUTHOR]

Abstract Urchin-like hierarchical Zn doped CdS powders were successfully synthesized via simple one-pot hydrothermal process. Their SEM and TEM images indicated that the hierarchical structure were assembled by single crystal nanorods with the hexagonal wurtzite phase. EDS element mapping verified that Zn ions were homogeneously distributed among the hierarchical microstructure. The performances of gas sensors based on pure and Zn doped CdS were measured and compared. The results indicated that Zn doping could enhance their responses to some volatile organic compounds and improve its selectivity to ethanol and toluene as well. The possible reasons for this enhancement were investigated. In addition, the sensor based on Zn doped CdS exhibited the ultrafast response and recovery to ethanol ( τ response < 1 , τ recovery = 8 s), indicating that the Zn doped CdS could be a promising gas sensing candidate for online monitoring of ethanol. Graphical abstract Image 1 Highlights • Hierarchical urchin-shaped Zn doped CdS was prepared via hydrothermal route. • The Zn element played a crucial role in enhanced gas sensing of CdS. • The Zn doped CdS microspheres exhibited excellent sensitivity. [ABSTRACT FROM AUTHOR]

Abstract Carbon-encapsulated transitional metal sulfides are considered as a promising anode material candidate for lithium ion batteries. Herein, a simple process is developed to synthesize 3D orostachys-like cobalt sulfides/C composites. This process is associated with the rational design of metal organic frameworks (MOFs) and subsequent in-situ sulfurization. Benefit from its unique structures, this novel 3D orostachys-like cobalt sulfides@C composites delivers an excellent charge capacity of 791 mAh g−1 after 100 cycles at 0.2 A g−1 as well as high stability of 667 mA g−1 after 700 cycles at 1 A g−1. Pseudocapacitive behaviors enhanced the electrochemical performance of 3D orostachys-like cobalt sulfides@C composites. Graphical abstract Scheme illustrating the benefit of hierarchical micro/nano-structure of Co 1-x S/C composites. Image 1 Highlights • Novel orostachys-like metal-organic frameworks were synthesized. • Cobalt sulfide nanoparticles uniformly embedded in hierarchical porous carbon network. • Several features of the hybrids lead to excellent lithium storage performance. • Pseudocapacitive behaviors enhanced the electrochemical performance of the hybrids. [ABSTRACT FROM AUTHOR]

The potential applications of superamphiphobic surfaces are widespread and attractive. The design of re-entrant structures is crucial to superamphiphobic surfaces. However, both the existing two strategies to design re-entrant structures face problems. Here a creative strategy to design 3D re-entrant nanostructures on ordered microstructures is proposed. A novel “Top-down” and “Bottom-up” hybrid method consisting of ultrafast laser ablation and chemical bath processing is used to fabricate hierarchical surfaces with 3D re-entrant CuO nanograss on Cu microcones. Thanks to the low surface energy from modification with perfluorodecyltrimethoxysilane and plenty of re-entrant geometries provided by the 3D distributed nanograss structures, the hierarchical surfaces show outstanding superamphiphobicity with water and low surface tension liquid like dodecane. The influence of the nanograss types and the microcone distribution on the superamphiphobicity are systematically studied. Besides, the microcones/nanograss hierarchical superamphiphobic surfaces show excellent long-term durability, high temperature durability and comprehensive mechanical durability, are promising for practically applications. [ABSTRACT FROM AUTHOR]

Abstract: The design and fabrication of biomass‐based energy storage devices is becoming a new trend to reduce the depletion of non‐renewable resources. Herein, β‐Ni(OH)2 nanosheet arrays grown on willow catkins‐derived hollow carbon microtubes is prepared for the first time through a facile acid treatment and subsequent hydrothermal process. In the β‐Ni(OH)2@acid‐treated carbon microtube [β‐Ni(OH)2@ACMT] composite, β‐Ni(OH)2 nanosheet arrays can be controllably grown on both internal and external surfaces of carbon microtubes, realizing effective utilization of the hollow tubular structure. In addition, carbon microtubes are not only employed as an effective support for the dispersion of β‐Ni(OH)2 nanosheets, but also served as a long‐range conductive micro‐current collector for electron transfer. Furthermore, the hollow tubular structure accompanied by the capillary effect provides fast channels for ion diffusion. As a consequence of this unique hierarchical structure, the electrode based on the β‐Ni(OH)2@ACMT composite exhibits a high specific capacitance of 1568 F g−1 at 1 A g−1, remarkable capacitance retention of 51.0 % even at 20 A g−1, and excellent cycling stability of 84.3 % retention after 3000 cycles. An asymmetric supercapacitor, with β‐Ni(OH)2@ACMT composites as the positive electrode and porous carbon microtubes as the negative electrode, achieves a high energy density of 37.8 W h kg−1 at 750 W kg−1, indicating its potential application in energy storage devices. [ABSTRACT FROM AUTHOR]

Materials with highly ordered molecular arrangements have the capacity to display unique properties derived from their nanoscale structure. Here, the synthesis and characterization of azobenzene (AZO)-functionalized siloxane oligomers of discrete length that form photoswitchable supramolecular materials are described. Specifically, synergy between phase segregation and azobenzene crystallization leads to the self-assembly of an exfoliated 2D crystal that becomes isotropic upon photoisomerization with UV light. Consequently, the material undergoes a rapid athermal solid-to-liquid transition which can be reversed using blue light due to the unexpectedly fast 2D crystallization that is facilitated by phase segregation. In contrast, enabling telechelic supramolecular polymerization through hydrogen bonding inhibits azobenzene crystallization, and nanostructured pastes with well-ordered morphologies are obtained based on phase segregation alone, thus demonstrating block copolymer-like behavior. Therefore, by tailoring the balance of self-assembly forces in the azobenzene-functionalized siloxane oligomers, fast and reversible phase-changing materials can be engineered with various mechanical properties for applications in photolithography or switchable adhesion to lubricant properties. [ABSTRACT FROM AUTHOR]

Two hierarchical ZnO micro/nano-materials have been prepared by a short-time (45 min) hydrothermal reaction without any surfactants. The different morphologies have been characterized comprehensively by XRD, SEM, TEM and XPS technologies. The hierarchical micro- and nano-structures are respectively consisted by the subordinate nano-pieces and nano-hexagonal-rods. Under the illumination of the simulated solar light, the nano-piece-aggregate spends 40 min to degrade the 98% of rhodamine 6G solution (10 −5 mol/L), whereas the nano-rod-aggregate only degrades the 78% of the solution in the same condition. Moreover, the photocatalytic performances of the two ZnO aggregates are significantly improved by loading with Au nanoparticles (NPs) in the same assembly process. The nano-piece-aggregate decorated with the Au NPs spends 24 min to decompose the rhodamine 6G solution completely, while nano-rod-aggregate decorated with the Au NPs needs 28 min. The related photocatalytic mechanisms are proposed in this paper. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) nanomaterials (i.e., graphene and its derivatives, transition metal oxides and transition metal dichalcogenides) are receiving a lot attention in energy storage application because of their unprecedented properties and great diversities. However, their re-stacking or aggregation during the electrode fabrication process has greatly hindered their further developments and applications in rechargeable lithium batteries. Recently, rationally designed hierarchical structures based on 2D nanomaterials have emerged as promising candidates in rechargeable lithium battery applications. Numerous synthetic strategies have been developed to obtain hierarchical structures and high-performance energy storage devices based on these hierarchical structure have been realized. This review summarizes the synthesis and characteristics of three styles of hierarchical architecture, namely three-dimensional (3D) porous network nanostructures, hollow nanostructures and self-supported nanoarrays, presents the representative applications of hierarchical structured nanomaterials as functional materials for lithium ion batteries, lithium-sulfur batteries and lithium-oxygen batteries, meanwhile sheds light particularly on the relationship between structure engineering and improved electrochemical performance; and provides the existing challenges and the perspectives for this fast emerging field. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) interconnected metal alloy nanostructures possess superior catalytic performance owing to their advantageous characteristics, including improved catalytic activity, corrosion resistance, and stability. Hierarchically structured Ni-Cu alloys composed of 3D network-like microscopic branches with nanoscopic dendritic feelers on each branch were crafted by a facile and efficient hydrogen evolution-assisted electrodeposition approach. They were subsequently exploited for methanol electrooxidation in alkaline media. Among three hierarchically structured Ni-Cu alloys with different Ni/Cu ratios (Ni0.25Cu0.75, Ni0.50Cu0.50, and Ni0.75Cu0.25), the Ni0.75Cu0.25 electrode exhibited the fastest electrochemical response and highest electrocatalytic activity toward methanol oxidation. The markedly enhanced performance of Ni0.75Cu0.25 eletrocatalyst can be attributed to its alloyed structure with the proper Ni/Cu ratio and a large number of active sites on the surface of hierarchical structures. [ABSTRACT FROM AUTHOR]

The formation of micropatterns combining nanostructured (porous) Si (NPSi) and bulk Si is induced by a sequential process of selective high energy ion irradiation and anodic etching. In this work, we investigate the microstructural origin of the increase of Si resistivity on irradiated areas, which is responsible for the inhibition of NPSi formation upon anodization. The increase of Si resistivity after irradiation at variable fluence has been evidenced from current voltage (I-V) characteristics. Microstructural aspects of the Si interfaces irradiated with 1.5–20 MeV Si ions have been revealed by elastic backscattering experiments in channeling configuration, Raman spectroscopy and high resolution transmission electron microscopy. It is concluded that inhibition of NPSi formation is induced at fluences that do not imply amorphization. In fact, the analysis of electrochemical capacitance-voltage measurements suggests that, at fluences well below the threshold for lattice disruption, the concentration of holes suffers from a drastic decrease at depths that match the location of maximum damage yield of the implanted Si ions. These results suggest that the mechanism responsible of formation of hierarchical Si structures is the local B dopant deactivation in the irradiated areas. [ABSTRACT FROM AUTHOR]

The utilization of porous carbon frameworks as hosts for sulfur loading is an important theme in current Li-S battery research. Unfortunately, the high loading of insulating sulfur often leads to low specific capacities, poor rate properties, and rapid capacity loss. To address this challenge, a facile templating route to fabricate a novel host material, hierarchical porous carbon rods constructed by vertically oriented porous graphene-like nanosheets (HPCR) is presented. With a high specific surface area, ultralarge pore volume, hierarchical porous structures, and ideal ion transfer pathways, HPCR is a promising candidate for high sulfur loading. When used as the active material for a sulfur cathode, the HPCR-S composite with 78.9 wt% sulfur exhibits excellent rate performance (646 mAh g−1sulfur at 5 C) and cycling stability (700 mAh g−1sulfur after 300 cycles at 1 C). Even with a sulfur content of 88.8 wt%, the HPCR-S composite, without any additional protective polymer coating, still delivers a good rate performance (545 mAh g−1sulfur at 3 C) and cycling stability (632 mAh g−1sulfur after 200 cycles at 1 C). More importantly, the high sulfur loading (88.8 wt%) ensures that the HPCR-S composite has a high energy density (880 mAh cm−3cathode after 200 cycles at 1 C). [ABSTRACT FROM AUTHOR]

Silk fibers spun by silkworms or spiders at ambient temperature display unique mechanical strength, excellent biocompatibility and optical transparency, which offer unconventional interfaces to soft and curved biological systems. In comparison with conventional materials, the performance of soft matter, i.e., animal silks, is mainly determined by the structure at the mesoscale. To further extend the applications, functionalization of silk materials becomes is required, and mesoscopic material assembly (MMA) was developed for this task. This feature article provides an overview on the principles and strategies concerning MMA, and some typical examples of functionalizing silk fibroin materials. The main strategies of MMA include in vivo and in vitro assemblies, and can be implemented by the three different paths: (1) molecular recognition, (2) surface functionalization of nanomaterials, or (3) foreign molecule mediation. The cases include the functionalization of silk fibroin materials by one/two-photon fluorescent molecules, quantum dots (QDs) and gold clusters, etc. The applications of these functionalized materials in bio waveguide, white-light-emitting devices, bioimaging, were also highlighted. MMA provides a practical tool for the production of the functionalized biocompatible materials, which can be further applied to fabricate high-performance bio integrated devices used in consumer electronics, and biomedical diagnosis, as well as human-machine interfaces. [ABSTRACT FROM AUTHOR]

Graphene scroll is an emerging 1D tubular form of graphitic carbon that has potential applications in electrochemical energy storage. However, it still remains a challenge to composite graphene scrolls with other nanomaterials for building advanced electrode configuration with fast and durable lithium storage properties. Here, a transition-metal-oxide-based hierarchically ordered 3D porous electrode is designed based on assembling 1D core-sheath MnO@N-doped graphene scrolls with 2D N-doped graphene ribbons. In the resulting architecture, porous MnO nanowires confined in tubular graphene scrolls are mechanically isolated but electronically well-connected, while the interwoven graphene ribbons offer continuous conductive paths for electron transfer in all directions. Moreover, the elastic graphene scrolls together with enough internal voids are able to accommodate the volume expansion of the enclosed MnO. Because of these merits, the as-built electrode manifests ultrahigh rate capability (349 mAh g−1 at 8.0 A g−1; 205 mAh g−1 at 15.0 A g−1) and robust cycling stability (812 mAh g−1 remaining after 1000 cycles at 2.0 A g−1) and is the most efficient MnO-based anode ever reported for lithium-ion batteries. This unique multidimensional and hierarchically ordered structure design is believed to hold great potential in generalizable synthesis of graphene scrolls composited with oxide nanowires for mutifuctional energy storage. [ABSTRACT FROM AUTHOR]

Monodispersed hierarchically nanostructured yttrium-based materials including Y(OH)3, Y6O5F8, and H-NaYF4 were successfully synthesized from the same mesocrystal Y(OH) xF3- x precursor. It was found that there was a close crystallographic relationship between the precursor and the final products and all of the processes underwent an in situ topotactic transformation. [ABSTRACT FROM AUTHOR]

Hierarchical Fe3O4@polypyrrole nanocages constructed with thin nanosheets are synthesized via a reduction and in situ polymerization route. They exhibit a stable cycling performance (650 mA h g−1 capacity at 2000 mA g−1 after 500 cycles) and superior rate capability (reversible capabilities of 1120, 950, 796, 657, and 490 mA h g−1 at 100, 300, 1000, 2500, and 5000 mA g−1, respectively). [ABSTRACT FROM AUTHOR]

A three-dimensional hierarchical porous ZnO with tubular structure has been prepared by calcining a tubular hierarchical hydrozincite precursor. The precursor was prepared through in situ growth of nanosheets on an as-synthesized template of zinc complex nanotubes at room temperature without using organic solvent, surfactant agent, and foreign template. The obtained three-dimensional hierarchical porous ZnO was characterized by XRD, SEM, HRTEM, BET, and FT-IR. The results show that the three-dimensional hierarchical porous ZnO, having a specific surface area of 78 m 2 g −1 , consists of interleaving mesoporous nanosheets composed of ZnO nanoparticles. Also its gas sensing properties were investigated, and the three-dimensional hierarchical porous ZnO shows superior gas sensing performance toward ethanol because the widely open and porous structure offers efficient gas diffusion route and the large specific surface area and small particle size supply abundant active sites for the gas adsorption. [ABSTRACT FROM AUTHOR]

To obtain high stability and electrical properties simultaneously is crucial for applications of Cu nanomaterials in microelectronics. In this work, multi-crystalline Cu nanoparticles were synthesized in the presence of PVP and SDS. Each as-grown particle was capped by a non-crystalline organic layer. The capped particles were only slightly oxidized after being stored under harsh ambient conditions for 3 months. Annealing at 250 °C and 500 °C in Ar was used to lower the electrical resistivity by five to six orders of magnitude. After being annealed at 250 °C, the original capping layer changed into a shell layer of thinner and uniform thickness. Although the electrical properties improved, oxidation of Cu into Cu 2 O was found during storage. Highly conductive and stable Cu–organic composite nanoparticles with hierarchical structures were obtained by heat treatment at 500 °C. The organics did not decompose completely but reacted with Cu to form a crystalline inner shell with a bcc structure and a non-crystalline outer shell. Small crystalline particles of 3–10 nm precipitated out within the outer shell layer and self-assembled on the surfaces of the Cu particle cores. The hierarchical Cu nanoparticles underwent no obvious enlargement and showed potential for fabricating electrical interconnections, sensors, and bionic structures. [ABSTRACT FROM AUTHOR]

Directional driving of a droplet can be achieved on a gradient-exhibiting, nanostructured microhump (GNMH) surface at low temperature and high humidity. The GNMH surface is fabricated using a commercial carbon fiber plate with an array of microscale hump structures; nanotechniques are used to form varying nanostructures on the microhump array, producing the micro- and nanostructured surface. The different nanostructures result in a wettability gradient along the surface, enabling droplet transport with the help of vibration-even at low temperature or high humidity. In contrast, simply nanostructured surfaces or microstructured surfaces that also have a wettable gradient do not enable droplet transport at low temperature or high humidty. In a range of subzero temperatures or in a range of high-humidity conditions, the GNMH surface retains its superhydrophobicity and ability for directional droplet transport along its wettability gradient. These results may assist in the design of surfaces required for cold environments, such as microreactors, chemical analytic devices, and sensors. [ABSTRACT FROM AUTHOR]

Bismuth telluride based thermoelectric materials have been commercialized for a wide range of applications in power generation and refrigeration. However, the poor machinability and susceptibility to brittle fracturing of commercial ingots often impose significant limitations on the manufacturing process and durability of thermoelectric devices. In this study, melt spinning combined with a plasma-activated sintering (MS-PAS) method is employed for commercial p-type zone-melted (ZM) ingots of Bi0.5Sb1.5Te3. This fast synthesis approach achieves hierarchical structures and in-situ nanoscale precipitates, resulting in the simultaneous improvement of the thermoelectric performance and the mechanical properties. Benefitting from a strong suppression of the lattice thermal conductivity, a peak ZT of 1.22 is achieved at 340 K in MS-PAS synthesized structures, representing about a 40% enhancement over that of ZM ingots. Moreover, MS-PAS specimens with hierarchical structures exhibit superior machinability and mechanical properties with an almost 30% enhancement in their fracture toughness, combined with an eightfold and a factor of six increase in the compressive and flexural strength, respectively. Accompanied by an excellent thermal stability up to 200 °C for the MS-PAS synthesized samples, the MS-PAS technique demonstrates great potential for mass production and large-scale applications of Bi2Te3 related thermoelectrics. [ABSTRACT FROM AUTHOR]

A functionally graded Al-doped ZnO structure is presented which combines conductivity, visible transparency and light scattering with mechanical flexibility. The nano- and meso-architectures, constituted by a hierarchical, large surface area, mesoporous tree-like structure evolving in a compact layer, are synthesized at room temperature and are fully compatible with plastic substrates. Light trapping capability is demonstrated by showing up to 100% improvement of light absorption of a low bandgap polymer employed as the active layer. [ABSTRACT FROM AUTHOR]

As macroscopic three dimensional (3D) architectures show increasing significance, much effort has been devoted to the hierarchical organization of 1D nanomaterials into serviceable macroscopic 3D assemblies. How to assemble 1D nanoscale building blocks into 3D hierarchical architectures is still a challenge. Herein we report a general strategy based on the use of ice as a template for assembling 1D nanostructures with high efficiency and good controllability. Free-standing macroscopic 3D Ag nanowire (AgNW) assemblies with hierarchical binary-network architectures are then fabricated from a 1D AgNW suspension for the first time. The microstructure of this 3D AgNW network endows it with electrical conductivity and allows it to be made into stretchable and foldable conductors with high electromechanical stability. These properties should make this kind of macroscopic 3D AgNW architecture and it composites suitable for electronic applications. [ABSTRACT FROM AUTHOR]

Abstract: A facile two-step method was developed for a large-scale growth of hierarchical MnCo2O4.5 nanostructure modified MnOOH nanorods (MC hybrid materials) as an efficient catalyst for water treatment. The synthesis involved a one-step hydrothermal process to prepare MnOOH nanorods and subsequently a simple solution method using hydrothermally synthesized MnOOH nanorods as both the template and Mn source to obtain MnCo2O4.5/MnOOH (MC) hybrid materials. The as-prepared MC hybrid materials with hierarchical structures could provide more active sites for catalytic degradation of methylene blue. These results indicate that the designed MC hybrid materials exhibit a promising capability for the degradation of dyes. [Copyright &y& Elsevier]

A form of photoelectrode architecture suitable for inorganic semiconductor solar cells is reported. The developed architecture consists of hierarchically organized TiO2 nanostructures with several tens of nanometer-sized particles that have a large surface area and open channels with several hundred-nanometer-gaps perpendicular to the substrate. These are tailored by controlling the kinetic energy of the ablated species during pulsed laser deposition (PLD). To fabricate the solar cells, CdS and CdSe inorganic sensitizers are assembled onto the architecture by successive ionic layer adsorption and reaction and polysulfide solution is used as an electrolyte with lead sulfide counter-electrodes. The inorganic semiconductor solar cells using the developed architecture (PLD-TiO2) show high energy conversion efficiencies of 5.57% compared to a conventional mesoporous TiO2 film(NP-TiO2) (3.84%) with an optical mask at 1 sun of illumination. The improved cell performance of PLD-TiO2 is attributed to greater light-harvesting ability, which results in the enhancement of the Jsc value. PLD-TiO2 absorbs more CdS/CdSe because of its larger surface area and excellent adhesion properties with fluorine-doped tin oxide (FTO) substrates. Additionally, due to its unique channel-shaped architecture, PLD-TiO2 has a longer electron lifetime compared to NP-TiO2. [ABSTRACT FROM AUTHOR]

Abstract: We propose an effective method of fabricating hierarchical nanoscale structures on microwrinkles for use in diverse applications. To do this, we introduce a wrinkling process to engender fine wrinkles using a method of repetitive dividing volume of ultraviolet curable resin. A plasma treatment technique then generates nanoscale protrusions on the microwrinkles. With this simple two-step process, we create interesting hierarchical micro- and nanoscale structures that exist in natural objects, such as the surface structure of a lotus leaf. We investigate changes in the contact angles on a flat, hierarchical structure. The proposed method presents a simple means of creating micro- and nanoscale hierarchical structures for hydrophobic and biomimetic applications. [Copyright &y& Elsevier]

Highlights: [•] Novel stick-like CuS hierarchical structures were fabricated by a hydrothermal approach use β-cyclodextrin as ligand and structure-directing agent. [•] The CuS stick-like structures are composed of tens to hundreds of well-arranged and self-assembled nanoplates with a thickness of about 25nm. [•] β-cyclodextrin is found to be the key factor in controlling the morphologies. [•] The results reveal that the as-prepared CuS exhibits outstanding cycle stability, indicating that it might find possible application as a cathode material for Lithium-ion batteries in the long term. [Copyright &y& Elsevier]

Sieve and take: A biomimetic strategy was designed to fabricate two‐dimensional silica sieve plates (SSP) by use of catanionic surfactants as composite template and L‐tartrate with hydroxyl and carboxyl groups as regulator. Tartrate was found to combine two capabilities in the formation of SSP structures: the connection of adjacent silica structures through H bonding and the separation of adjacent structures through electrostatic repulsion. [ABSTRACT FROM AUTHOR]

Abstract: Pyramid-like magnetite crystals are assembled via a simple one-pot hydrothermal process with industrialized environmental free raw materials. It is revealed that these crystals have hierarchical structures which are self-assembled of nano-sized ultrafine magnetite spheres. The electrochemical properties of the as-prepared magnetite are studied by galvanostatic cell cycling at different current rates. The electrodes exhibit high reversible specific capacity (about 1600mAhg−1 at 40mAg−1 ) at low rate and good cycle property at 1C. The specific capacity increases after it reaches a minimum, which is believed to be related to the formation of SEI film. After cycled 500 times at 1C, the reversible capacity is still higher than 340mAhg−1. [Copyright &y& Elsevier]

Abstract: Surface activity of heterogeneous catalysts can be enhanced if their sizes are reduced to nanometers. However, loose nanomaterials pose potential health and environmental risks. This issue has been addressed by attachment of palladium nanoparticles on multi-scale hierarchical carbon supports that have exceptionally high surface area per volume. The supports consist of porous carbon foam whose surface has been either chemically functionalized, or morphologically altered by grafting of carbon-nanotubes. It is seen that whereas chemical functionalization does provide some increase in nano-catalyst loading, morphological modification is significantly more powerful. It has the potential to create orders of magnitude increase in catalytic activity within the same overall volume. The synthesis techniques have been investigated in sufficient detail to provide significant control over the density and size of nanoparticles. Abundant distribution of nanoparticles is observed even within the deeper pores of the microcellular foam. The nanoparticles are seen to be metallic Pd having face centered cubic structure. Additionally, the nano-particles and nanotubes are durable, and remain attached to the base support after long periods of rapid rotation in water. These robust hybrid structures show promise in future applications such as sensors, water purification systems, fuel cell electrodes and hydrogen storage sponges. [Copyright &y& Elsevier]

Abstract: To expand the application of electrospun fibers or electrosprayed beads, micro-nano hierarchical structures of polystyrene (PS) have been constructed through the adjustment of solvent, polymer concentration, environment humidity, electrospinning temperature, etc. Primary structures, such as fibers, beads and bead-on-string structure, as well as secondary structures, such as nanopores, nanopapilla and net-work structure, have been constructed. Solvent plays an important role in the construction of both primary structures and secondary structures. By using N,N-dimethylformamide (DMF), tetrahydrofuran (THF) and mixed solvent of DMF/THF, the micro-nano hierarchical structures can be controlled. Humidity is a key factor to the construction of secondary structures. The obtained fibers or beads have smooth surface at low humidity. While at high humidity, secondary structures tend to appear. For the PS/DMF system, vapor-induced phase separation may be the most pertinent mechanism to explain the formation of secondary structures. While for the PS/THF system, breath figure theory can explain the formation of uniform nanopores properly. [Copyright &y& Elsevier]

Abstract: We report on a rapid, single-step method to produce large-area superhydrophobic surfaces via acetone-induced phase transformation of polycarbonate. Crystallization of the polymer leads to the formation of a hierarchical structure composed of microporous spherulites covered with nano-fibrils, and resulted in superhydrophobic wetting behavior. A systematic study of the dependence of surface morphology on the acetone treatment time was conducted to optimize the treatment time and to elucidate the structure formation mechanism. The resulting surfaces exhibit high contact angles, low contact angle hysteresis, and complete dewetting during droplet impact. Theoretical analysis of the wetting and anti-wetting pressures shows that the nano-scale morphology is critical for achieving droplet impact resistance. This simple phase transformation approach could be more broadly applied to other solvent–polymer systems for fabricating large-area hierarchical surface textures. [Copyright &y& Elsevier]

Abstract: Uniformly-shaped, micron-scale particles with nanoscale layers of Al and Ni and a volume fill of 20%±1% were fabricated by depositing Al/Ni multilayer films onto mesh substrates with a square weave. The films break into individual particles at the weave intersections during removal and the resulting particles have lengths equal to three times their widths. Exothermic formation reactions in loose compacts of these particles were shown to self-propagate up to 200 times slower than reactions in continuous multilayer foils with similar chemistries, layer thicknesses and ignition thresholds. The difference is attributed to the time delay associated with heating each subsequent particle to the point of ignition as the reaction propagates. The results presented here demonstrate an ability to separately control the rate of mass diffusion and the rate of thermal diffusion in particle compacts and thereby produce slow and stable self-propagating formation reactions. Such reactions are desirable for both industrial and military applications such as chemical time delays. [Copyright &y& Elsevier]

Abstract: Novel α-Zn3(PO4)2·4H2O hierarchical sphere structures have been synthesized by a simple chemical method through the reaction between zinc acetate and orthophosphoric acid by using cetyltrimethylammonium bromide (CTAB) as capping reagent at room temperature. The structures and morphologies of the as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscopy (TEM). The influences of the synthetic parameters on the morphologies of the final products were investigated. The experimental results clearly show that both the concentration of CTAB aqueous solution and the concentration of initial reagents play important roles in the formation of the α-Zn3(PO4)2·4H2O hierarchical sphere structure. Detailed proofs indicated that the process of crystal growth was dominated by a self-assembly growth mechanism. [ABSTRACT FROM AUTHOR]

Abstract: This study presents the wetting properties, including hydrophilicity, hydrophobicity and anisotropic behavior, of water droplets on the silicon wafer surface with periodical nanopatterns and hierarchical structures. This study fabricates one- and two-dimensional periodical nanopatterns using laser interference lithography (LIL). The fabrication of hierarchical structures was effectively achieved by combining photolithography and LIL techniques. Unlike conventional fabrication methods, the LIL technique is mainly used to control the large-area design of periodical nanopatterns in this study. The minimum feature size for each nanopattern is 100nm. This study shows that the wetting behavior of one-dimensional, two-dimensional, and hierarchical patterns can be obtained, benefiting the development of surface engineering for microfluidic systems. [Copyright &y& Elsevier]

Abstract: “Chimie douce” based strategies allow, through the deep knowledge of materials chemistry and processing, the birth of the molecular engineering of nanomaterials. This feature article will highlight some of the main research accomplishments we have performed during the last years. We describe successively the design and properties of: sol–gel derived hybrids, Nano Building Blocks (NBBs) based hybrid materials, nanostructured porous materials proceeds as thin films and ultra-thin films, aerosol processed mesoporous powders and finally hierarchically structured materials. The importance of the control of the hybrid interfaces via the use of modern tools as DOSY NMR, SAXS, WAXS, Ellipsometry that are very useful to evaluate in situ the hybrid interfaces and the self-assembly processes is emphasized. Some examples of the optical, photocatalytic, electrochemical and mechanical properties of the resulting inorganic or hybrid nanomaterials are also presented. [Copyright &y& Elsevier]

Abstract: Here we demonstrate the utility of hierarchically designed alumina templates for the formation of palladium Y-junction nanostructures through a chemical vapor deposition route. These structures exhibit enhanced electrocatalytic activity for the oxidation of formic acid (up to 1020%) compared to that of platinum Y-junction nanostructures, which could be of immense relevance to portable fuel cell technology, since designing a better electrocatalyst for fuel cell reactions continues to be an important challenge. Apart from the obvious applications in fuel cell electrocatalysis, these Y-junction nanostructures could also act as promising candidates for room temperature hydrogen separation and more importantly as interconnects in molecular scale electronic devices. The present method of fabrication of Y-junction nanostructures using hierarchical alumina templates could be extended to other metallic/semiconducting systems facilitating more general opportunities for such hierarchical designs in nanoelectronics. [Copyright &y& Elsevier]

• Several representative 2D materials and their hybrids were selected as the main research objects. • The synthesis and absorption properties of 2D-based absorbers in the last four years were summarized. • The EMW absorption mechanisms of various 2D-based absorbers were summarized in detail. • Prospects and shortcomings of 2D-based absorbers were presented. [Display omitted] Two-dimension (2D) nanomaterials with high specific area, low density and special electric behavior have attracted tremendous interest in the field of electromagnetic wave (EMW) absorption. Continuous and growing efforts have been committed to satisfy the demands of good impedance matching and strong attenuation capacity of 2D-based EMW absorption nanomaterials in past several years, and the ultimate aim of these materials is to develop potential candidates of high-performance absorption materials. In this review, we will summarize the latest progress (in the last four years) of 2D nanomaterials for EMW absorption, including graphene, MXenes, MoS 2 nanosheets, layered double hydroxides (LDHs), graphite-like C 3 N 4 (g-C 3 N 4), and other representative transition metal dichalcogenides (TMDs). Moreover, the synthesis methods, structures, absorption mechanisms and performances of some excellent achievements will be presented. The aim of this review is to provide readers with a systematic overview of the relationship between 2D structures and absorption properties, and guide the future design of novel 2D electromagnetic wave absorption materials (EWAMs) by discussing the impedance matching and attenuation capacity of these recent advances. This review also intends to prompt fresh concepts for designing prominent high-performances EWAMs. [ABSTRACT FROM AUTHOR]

Abstract: Nanosheet- or nanorod-based microspheres and nanorod-based microrods of polyaniline (PANI) with hierarchical structures were successfully prepared by oxidation polymerization of aniline in alkaline solution. Temperature was found to have important influence on the morphology of PANI hierarchical structures and their building blocks. The concentration of alkali (NaOH) could be used to guide the morphological evolution of PANI, from leaf-like structures to nanosheet-based particles, and to nanorod-based microspheres and nanorod-based microrods with increasing concentration of NaOH in synthesis. The chemical structures of product were characterized by FTIR, UV–vis spectra and XRD, and its solubility was also studied in this report. [Copyright &y& Elsevier]

• Multiscale porous MXene films are sequentially formed by oxidation and pH-controlled crumpling. • Mesopores generated from partial oxidation process greatly facilitate the ion diffusion. • Macropores formed by crumpling would prevent the restacking problem of MXene. • Increased porosity and specific surface area of porous MXene result in high capacitance in supercapacitors. [Display omitted] MXene, an example of two-dimensional (2D) transition metal carbides, is a promising electrode material for batteries and supercapacitors because of its excellent electrochemical properties derived from transition metal carbide/nitride constituents and its high electrical conductivity. However, similar to other 2D nanomaterials, MXene-based electrodes have a notable shortcoming of reduced specific surface area and reduced ion diffusion due to the self-restacking of MXene nanosheets. Here, to overcome these limitations, we present a novel method to create oxidized-co-crumpled multiscale porous architectures of MXene by a sequential process consisting of partial oxidation by hydrogen peroxide and then flocculation in acid. These treatments result in simultaneous generation of mesopores by oxidation and macropores caused by structural crumpling. This oxidized-co-crumpled MXene has a five times larger specific surface area (72 m2/g) than pristine MXene. In addition, the capacitance performance (307 F/g at 20 mV/s under 1 M H 2 SO 4) and the capacitance at a higher scan rate (225 F/g at 100 mV/s) are improved. Additionally, after 6000 cycles, 87.6% of the capacitance is retained. Such an improvement in the properties is attributed to the structural advantages of the multiscale porous oxidized-co-crumpled MXene, wherein ion diffusion through mesopores is facilitated, while the crumpled macropores prevent re-stacking. Overall, this study demonstrates a promising strategy to create MXene-based high performance electrode materials for a variety of electrochemical applications. [ABSTRACT FROM AUTHOR]

Detailed and accurate three-dimensional (3D) information about the morphology of hierarchically structured materials is derived from multi-scale X-ray computed tomography (XCT) and subsequent 3D data reconstruction. High-resolution X-ray microscopy and nano-XCT are suitable techniques to nondestructively study nanomaterials, including porous or skeleton materials. However, laboratory nano-XCT studies are very time-consuming. To reduce the time-to-data by more than an order of magnitude, we propose taking advantage of a monitored tomographic reconstruction. The benefit of this new protocol for 3D imaging is that the data acquisition for each projection is interspersed by image reconstruction. We demonstrate this new approach for nano-XCT data of a novel transition-metal-based materials system: MoNi4 electrocatalysts anchored on MoO2 cuboids aligned on Ni foam (MoNi4/MoO2@Ni). Quantitative data that describe the 3D morphology of this hierarchically structured system with an advanced electrocatalytically active nanomaterial are needed to tailor performance and durability of the electrocatalyst system. We present the framework for monitored tomographic reconstruction, construct three stopping rules for various reconstruction quality metrics and provide their experimental evaluation. [ABSTRACT FROM AUTHOR]

• We first develop a simple film with good wet strength, rapid water response and water-induced shape memory. • The mechanical robustness of MCP films is improved in low pH solutions, and the films show a rapid pH stimulus response. • MCP films exhibit excellent water-induced shape memory and a rapid pH stimulus response. • After rapid bend-release repetitions (0°–90°–0°) for 500 cycles, the resistive bending sensor deliver stable electrical signals. [Display omitted] Development of multi-functional water-sensitive shape memory material is crucial for applications in smart textiles, artificial intelligence, and biomedical areas. However, it remains a great challenge to achieve good biocompatibility, rapid water response, and robust mechanical strength in one single material. In this respect, we report a green approach to produce a series of multi-functional water-sensitive memory films (named MCP films) from sisal cellulose microcrystals (MSF-g-COOH), peach gum polysaccharide (PGP), citric acid (CA), and graphene nanosheets (GN). After crosslinking with CA, MCP films exhibit excellent water-induced shape memory and rapid pH stimulus response. More importantly, MCP films can effectively amplify different external motion stimuli by converting them into independent electrical signals to achieve accurate and continuous perception of bending. A high-performance resistive bending sensor was further fabricated from the MCP films to mimic natural human skin. The resistive bending sensor exhibited excellent water-responsive shape memory, self-adhesion, and bending sensitivity, which can be used in electronic skin, human-machine interactions, intelligent wearable devices, personalized health monitoring and other applications. Our work successfully demonstrates the application of the water-sensitive shape memory films in electronic skin and health-monitoring components, and fills the gap between material design and high-performance devices. [ABSTRACT FROM AUTHOR]

• Heterostructured Zn 2 SnO 4 /ZnO microflowers were successfully prepared. • The Zn 2 SnO 4 /ZnO microflowers feature an assembly of porous nanosheets. • The Zn 2 SnO 4 /ZnO microflowers showed an improved CH 4 sensing properties. In recent years, design and synthesis of heterostructured nanomaterials with high gas-sensing performance for detection of flammable and toxic gases has attracted much research interest. In this paper, pristine and Zn 2 SnO 4 -decorated ZnO microflowers with the size about 2–5 μm and assembled by porous nanosheets of about 15 nm in thickness were successfully synthesized via a simple solvothermal method and subsequent calcination process. The methane (CH 4) sensing properties of the prepared Zn 2 SnO 4 /ZnO were investigated and compared with that of the pure ZnO counterpart. It was found that after decorating with a small amount of Zn 2 SnO 4 , the ZnO sensor showed an improved gas sensing properties to CH 4. At optimum operating temperature of 250 °C, the sensor based on SZ2 (Zn 2 SnO 4 /ZnO composite with the optimal Zn 2 SnO 4 contend) showed a response as high as 27.2 to 1000 ppm CH 4 , which was about 3.2 times higher than that of SZ0 (pristine ZnO) sensor. Meanwhile, the SZ2 sensor also showed a fast response and recover characteristic, low detection limit (1.48 ppm), good repeatability and long-term stability. The Zn 2 SnO 4 /ZnO heterostructures related CH 4 sensing mechanism was discussed. [ABSTRACT FROM AUTHOR]