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Radiation physics of the 21st century, which combines the special physical properties of materials and objects (nano-objects, fractals, and others) with a highly nonequilibrium state, demonstrates many unusual nonlinear effects and their interpretation. This is especially evident in the case of high-intensity irradiation of different natures and a wide energy spectrum. Taking into account five different channels of energy transfer from radiation to matter (elastic scattering, ionization, heat release, elastic waves, and shock waves) makes it challenging to manage new unusual combinations of radiation response, the study of which at the present stage is possible using the concept of "complexity." Among the various characteristics of irradiated objects, the hierarchy of their structure takes a special role, which is fundamental for objects of both inorganic and living nature. The peculiarity of including objects of a hierarchical structure in the analysis of radiation-induced effects leads to a new situation: the involvement of the ideas of cybernetics in radiation physics. Here, new issues arise concerning the relationship between radiation and information, in particular, the effect of the entire range of radiation parameters (energy, intensity, dose) on the transfer of information from the lower platform of hierarchical structures to higher ones and its compression at the same time. The solution to these problems requires the use of both new theoretical approaches and the modification of conventional schemes in relation to elementary acts of atomic rearrangements, such as kinetics and approaches to revealing the mechanisms of radiation-induced effects. These questions are formulated, and a certain solution has been obtained in relation to objects of inorganic and living nature. [ABSTRACT FROM AUTHOR]

This article proposes three new decompositions of inequality measures, drawn from the framework of cooperative game theory. It allows the impact of players' interactions, rather than players' contributions to inequality, to be taken into consideration. These innovative approaches are especially suited for the study of income inequality when the income has a hierarchical structure: the income is composed of several primary sources, with the particularity that each of them is also composed of secondary sources. We revisit the Shapley–Owen value that quantifies the importance of each of these secondary sources in the overall income inequality. Our main contribution is to decompose this importance into two parts: the pure marginal contribution of the considered source and a weighted sum of pairwise interactions. We then provide an axiomatic characterization of each additive interaction decomposable (AID) coalitional value considered in this paper. We give an application of these decompositions in the context of inequality theory. [ABSTRACT FROM AUTHOR]

[Display omitted] Here, we report a facile approach to fabricate large area ordered arrays of TiO 2 hierarchical nanostructures through space-confined seeding and growth on inverted pyramid templates. The mechanisms of space-confined seeding and growth have been systematically explored and studied. The drying TiO 2 seed precursor solution prefers to accumulate on the narrow structures including the centre and edges of the inverted pyramid structures, which facilitates to reduce the free energy of the precursor solution surface and form crystal seeds. Followed by hydrothermal treatment, selective growth of TiO 2 hierarchical nanostructures on desirable locations, such as only on the centre, only on the edges, or on the entire surface of the inverted pyramid templates, can be achieved. In addition, the growth temperature, duration and solvents affect the morphology of TiO 2 hierarchical nanostructures. This work may provide a universal approach to obtain ordered arrays of metal oxide (e.g. ZnO and MnO 2 , etc.) nanostructures for applications in optics, electrics, energy, and catalysis. [ABSTRACT FROM AUTHOR]

The industrial interest in the patterning of polymeric surfaces at the micro/nanoscale to include new functionalities has considerably increased during the last years. Hierarchical organization of micro/nanometric surface textures yields enhanced functional properties such as hydrophobicity, hydrophilicity, antibacterial activity, and optical or chromatic effects to cite some. While high accuracy methods to pattern hierarchical surfaces at the nanoscale have been developed, only some of them have been applied for high volume manufacturing with limited success, mainly because they rely on the use of expensive machinery and moulds or complicated inserts. Therefore, a method using low cost recyclable tooling and process conditions applicable to high-volume manufacturing is currently missing. In this work, a scalable and low-cost method to replicate hierarchical micro/nanostructured surfaces on plastic films is presented, which can be latter used as inlays for injection moulded parts with standard processing conditions. This method is used to demonstrate the feasibility of replicating three level hierarchical micro/nano textured surfaces using recyclable bio-based polymers (of high relevancy in the current plastic pollution context) achieving replication ratios above 90%, comparing the replication results with those obtained in polypropylene. The presence of the micro/nanotextures substantially increases the contact angle of all the polymers tested, yielding values higher than 90° in all the cases. Also, various mechanical properties of the replicated parts for all the polymers injected are characterized one and thirty days after the samples were manufactured, showing fairly constant values. This highlights the validity of the replicated surfaces, regardless of the biopolymers special crystallization characteristics. [ABSTRACT FROM AUTHOR]

Li‐metal is gaining attention as a next generation anode active material, of which the primary attribute is its energy density. However, Li dendrite formation is the primary challenge. Herein, a design strategy with increased structural dimensions and hierarchy for Li‐metal anode is investigated to stabilize the dendrite formation for extending the cycle life with high reversibility. For this, diverse structural current collectors (CCs) are fabricated by manipulating structural design in different length scales and characterized as a Li‐metal anode. The hierarchy (i.e., nanostructures inside the microcavities) can not only reduce the current density on entire anode surface but also concentrate the local electrical field onto inner surfaces of the microstructures, inducing preferential Li nucleation inside microcavities and promoting confined growth of Li. It is confirmed that introduction of structural hierarchy can enhance the cycle life by 364% and the preservation of coulombic efficiency > 90% by 266%. The design strategy is extended by exploring a practical one‐step fabrication of the hierarchical CC with even greater performance via the inward growth mechanism. This work elucidates the mechanism of inward Li growth using tailored surface geometries for Li dendrite suppression, which can be a guideline for designing structured anode CCs for Li‐metal batteries. [ABSTRACT FROM AUTHOR]

Carbon nanotube (CNT) networks enable CNTs to be used as building blocks for synthesizing novel advanced materials, thus taking full advantage of the superior properties of individual CNTs. Multiscale analyses have to be adopted to study the load transfer mechanisms of CNT networks from the atomic scale to the macroscopic scale due to the huge computational cost. Among them, fully resolved structural features include the graphitic honeycomb lattice (atomic), inter-tube stacking (nano) and assembly (meso) of CNTs. On an atomic scale, the elastic properties, ultimate stresses, and failure strains of individual CNTs with distinct chiralities and radii are obtained under various loading conditions by molecular mechanics. The dependence of the cohesive energies on spacing distances, crossing angles, size and edge effects between two CNTs is analyzed through continuum modeling in nanoscale. The mesoscale models, which neglect the atomic structures of individual CNTs but retain geometrical information about the shape of CNTs and their assembly into a network, have been developed to study the multi-level mechanism of material deformation and microstructural evolution in CNT networks under stretching, from elastic elongation, strengthening to damage and failure. This paper summarizes the multiscale theories mentioned above, which should provide insight into the optimal assembling of CNT network materials for elevated mechanical performance. [ABSTRACT FROM AUTHOR]

In this paper, NiO, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and (CeO2)0.8(Sm2O3)0.2 (SDC) nanopowders with different microstructures were obtained using hydrothermal and glycol–citrate methods. The microstructural features of the powders were examined using scanning electron microscopy (SEM). The obtained oxide powders were used to form functional inks for the sequential microextrusion printing of NiO-SDC, SDC and LSCF-SDC coatings with resulting three-layer structures of (NiO-SDC)/SDC/(LSCF-SDC) composition. The crystal structures of these layers were studied using an X-ray diffraction analysis, and the microstructures were studied using atomic force microscopy. Scanning capacitance microscopy was employed to build maps of capacitance gradient distribution over the surface of the oxide layers, and Kelvin probe force microscopy was utilized to map surface potential distribution and to estimate the work function values of the studied oxide layers. Using SEM and an energy-dispersive X-ray microanalysis, the cross-sectional area of the formed three-layer structure was analyzed—the interfacial boundary and the chemical element distribution over the surface of the cross-section were investigated. Using impedance spectroscopy, the temperature dependence of the electrical conductivity was also determined for the printed three-layer nanostructure. [ABSTRACT FROM AUTHOR]

Abstract In this study, a bioinspired hierarchical structure was formed with superomniphobicity on a 7075 aluminium alloy using laser ablation. The morphology and wetting characteristics of the biomimetic sample surface were characterised using scanning electron microscopy, laser confocal microscopy, and contact angle measurements. The effect of the liquid properties and surface structures on the rolling behaviour was investigated. The results suggest that the fabricated biomimetic sample surface was a hierarchical structure. The prepared sample had superomniphobicity and low adhesion properties, and the contact angles of six different liquid droplets on the sample surface reached or approached 150°. Specifically, the largest contact angle was 152°, and the average rolling angle was 7.7°. This multi‐hydrophobic surface provides a valuable reference for the research study and use of a variety of solid–liquid contacts.

[Display omitted] • BHHMT specimens were designed and fabricated via additive manufacturing. • BHHMT not only significantly improved SEA , but also effectively reduced IPCF and ULC. • Parametric analysis was conducted to reveal the influence of hierarchical order, wall thickness, reinforcing rib on the axial crushing performance. • The MCF prediction model of BHHMT was derived theoretically. • The metal BHHMT-3 possessed a significantly higher SEA and equivalent SEA compared to other cellular structures. Inspired by the gradient hierarchical structures from the wood and bamboo, a new bio-inspired hierarchical hybrid multi-cell tubes (named BHHMT) were proposed. A systematic investigation on the crashworthiness of BHHMT with structural hierarchy was conducted experimentally, numerically, and theoretically to obtain the optimal parameter configuration. The results indicated that the specific energy absorption (SEA) of the 3rd order BHHMT was 49.10% higher than that of the single square tube. Moreover, the initial peak crushing force (IPCF) and the undulation of load-carrying capacity (ULC) used for evaluating the stability of the BHHMT under dynamic crushing were also considered. The IPCF and ULC of the 3rd order BHHMT reduced up to 18.37% and 77.21% compared to the single square tube. It indicated that the BHHMT had a larger potential to improve energy absorption than the square tube and conventional multi-cell square tube. Subsequently, a theoretical model was developed to estimate the mean crushing force (MCF) of the proposed tubes, which was in good agreement with the numerical results. Finally, the influence of various additive manufacturing materials on the crashworthiness of the BHHMT was investigated. It indicated that the metal BHHMT-3 exhibited a significantly higher SEA and equivalent SEA compared to other popular cellular structures. This study provided valuable insights and guidelines for designing protective structures with mechanical safety performance, including understanding the failure process. [ABSTRACT FROM AUTHOR]

• A new fractal multi-cell square tube (FMST) based on the Sierpinski carpet fractal is proposed. • Energy absorption performance of the FMST are numerically and theoretically studied. • The SEA of the 3rd order FMST is 100 % than that of the 0th order FMST. • The theoretical predictions of the MCF agree well with the numerical results. In this study, a new fractal multi-cell square tube (FMST) based on the fractal design of the Sierpinski carpet is proposed for energy absorption. The dynamic crushing performance and energy absorption characteristics of the FMST are numerically and theoretically investigated. Extensive numerical simulations are carried out for the FMST structures with different fractal orders and masses of the structures. The findings reveal that the specific energy absorption of the 3rd order FMST is significantly higher, exhibiting a remarkable 100 % increase compared to the 0th order FMST. Furthermore, the undulation of the load-carrying capacity of the 3rd order FMST is reduced by up to 88.5 % compared to a conventional square tube, indicating the substantial potential of the FMST for designing highly efficient energy absorbers. Comparative analysis against other hierarchical multi-cell square tubes reported in the literature confirms that the specific energy absorption of the FMST surpasses existing designs. In addition, a theoretical study is presented for the mean crushing force of the proposed FMST, employing the simplified super folding element theory. The theoretical predictions agree well with the numerical results, further validating the effectiveness of the proposed design. This study provides an innovative design of a multi-cell energy absorber with exceptional energy absorption efficiency. The incorporation of fractal principle in the FMST design holds promise for advancing the field of energy absorption, with potential applications in various industries. [ABSTRACT FROM AUTHOR]

Transition metal sulfides have shown promise as candidates for energy storage and conversion devices, but the limited electroactive sites may greatly hinder further improvement. The novel nanostructured morphologies enhance active sites and surface area, thereby increasing overall electrochemical performance. Herein, we successfully synthesized various morphologies such as ZnS spheres, CoS star anise spice-like structures, and NiS flakes-like structures, which were directly grown on Ni foam using a single-step hydrothermal method. Additionally, the novel nanostructured morphologies were combined as a heterojunction NiCoZnS electrode to further utilize electronic and junction properties, thereby enhancing performance. This combination of morphologies—spheres, star anise spice, and flakes-like structures with ultrathin thickness and large surface areas—effectively increases the number of active sites, resulting in enhanced supercapacitor and oxygen evolution reaction (OER) performance. Moreover, directly growing nanostructures on conductive Ni foam endows the electrode materials with higher conductivity and richer active sites. In terms of supercapacitor performance, the NiCoZnS electrode exhibits a specific capacity of 1171.3 C g−1 at 0.5 A g−1 and remarkable rate performance. Furthermore, NiCoZnS maintains a capacitance retention of 94.9 % after 5000 cycles. As an electrocatalyst, NiCoZnS undergoes a rapid self-reconstruction process during the oxygen evolution reaction (OER), producing rich oxygen vacancies and thus demonstrating remarkable long-term stability. The NiCoZnS nanocomposites exhibit small overpotential (157 mV at 100 mA cm−2) and a Tafel slope of 128 mV dec−1. NiCoZnS's unique hierarchical nanostructures, doping-optimized electronic structural configuration, and specific surface lead to high catalytic performance. These remarkable performances of mixed morphologies like NiCoZnS hold great promise for energy storage and conversion devices. [Display omitted] • NiCoZnS 3D/2D mixed morphologies were synthesized on nickel foam by a single step hydrothermal route. • The high electrochemical active surface area of NiCoZnS improves charge transfer and separation. • NiCoZnS had 1.93, 1.29x higher specific capacity than ZnS and CoZnS. • Enhancement comes from the ample space in the NiCoZnS electrode, adorned with sphere, star anise, and flake-like structures. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superhydrophobic & superoleophilic bronze surface by laser texturing and post-heating. • Post-heating enhanced adsorption of C–C(H) by bronze surface and increased CA. • Superolephilicity helps adsorption of lubricant, reduces bearing friction. • Superhydrophobicity enables anti-icing and self-cleaning. As a bearing material, bronze has high strength and hardness but is poor in anti-adhesion property. In this study, we propose a method to prepare a superhydrophobic and superoleophilic bronze surface by combining laser surface texturing and post-heat treatment. A picosecond laser was employed to produce pore arrays with varying spacings and depths on the bronze surface, which exhibited micro-nano hierarchical structures. A further post-heat treatment of the laser-textured sample at 150 °C in the ambient led to the formation of a superhydrophobic surface with a maximum water contact angle of 158° and with superoleophilicity. It was found that pore spacings played a significant role in forming the surface hierarchical structures, which were covered with the laser-ablated micro-nano particles. The pore depth, however, showed little influence on the surface wettability. Analysis of the surface chemical compositions by X-ray photoelectron spectroscopy (XPS) indicates that the C element mainly exists in the form of the C–C(H) group, which reduces the surface energy and leads to superhydrophobicity. It was also verified that the wettability transition of the bronze surface before and after heating was independent of the oxide transition. Rubbing tests were conducted to evaluate the durability of the surface hierarchical structure. Anti-icing and self-cleaning functions were demonstrated showing the potential of the developed method for preparing a superhydrophobic and superoleophilic surface. [ABSTRACT FROM AUTHOR]

Implantable electrodes are crucial for stimulation safety and recording quality of neuronal activity. To enhance their electrochemical performance, electrodeposited nanostructured platinum (nanoPt) and iridium oxide (IrOx) have been proposed due to their advantages of in situ deposition and ease of processing. However, their unstable adhesion has been a challenge in practical applications. This study investigated the electrochemical performance and stability of nanoPt and IrOx coatings on hierarchical platinum-iridium (Pt-Ir) substrates prepared by femtosecond laser, compared with the coatings on smooth Pt-Ir substrates. Ultrasonic testing, agarose gel testing, and cyclic voltammetry (CV) testing were used to evaluate the coatings’ stability. Results showed that the hierarchical Pt-Ir substrate significantly enhanced the charge-storage capacity of electrodes with both coatings to more than 330 mC/cm2, which was over 75 times that of the smooth Pt-Ir electrode. The hierarchical substrate could also reduce the cracking of nanoPt coatings after ultrasonic, agarose gel and CV testing. Although some shedding was observed in the IrOx coating on the hierarchical substrate after one hour of sonication, it showed good stability in the agarose gel and CV tests. Stable nanoPt and IrOx coatings may not only improve the electrochemical performance but also benefit the function of neurobiochemical detection.

High overpotential and poor long‐term operation stability of electrocatalysts are two major barriers for the hydrogen evolution reaction (HER). Herein, 2D ultrathin PdAgAu nanorings are synthesized and further self‐assembled on Ti2CTx–graphene oxide (GO) heterostructure for efficiently boosting HER. The best candidate, Pd50Ag31Au19/Ti2CTx–GO electrocatalyst, can initiate hydrogen evolution at an overpotential of 90 mV at 10 mA cm−2 and exhibits the lowest Tafel slope of 75 mV dec−1 as well as the highest mass activity of 284.4 mA mg−1Pd at −100 mV, in comparison with those of Pd50Ag31Au19/Ti2CTx, Pd50Ag31Au19/GO, and commercial Pd/C. Most remarkably, impressive long‐term stability is achieved even after a 112 h chronoamperometric test. The great performance of Pd50Ag31Au19/Ti2CTx–GO electrocatalyst can be attributed to the advantageous synergistic effect among the morphological modulation, composition optimization, and strong metal–support interaction effect between the Pd50Ag31Au19 nanorings and Ti2CTx–GO support.

Abstract The use of antibacterial and antifouling materials is widely being investigated to combat the increasing risk associated with bacterial infections and the evolution of drug‐resistant bacteria. Efficient antibacterial materials can be fabricated by mimicking the topography found on the surface of natural antibacterial materials. Natural materials such as the wings of cicadas and dragonflies have evolved to use the structural features on their surface to attain bactericidal properties. The nanopillars/nanospikes present on these natural materials physically damage the bacterial cells that settle on the nanostructures resulting in cell lysis and death. This article reviews the role of nanostructures found on the surface of some of these natural antibacterial and antifouling materials such as lotus leaf, cicadas and dragonflies wings, shark skin, and rose petals. These natural structures provide guidelines for the design of synthetic bio‐inspired materials. This review article also presents some novel fabrication techniques used to produce biomimetic micro‐ and nano‐structures on synthetic material surfaces. The role of size, shape, aspect ratio, and spacing between the micro/nano‐structures on the bactericidal properties is also discussed. Finally, the review is finished with the author's view on the future of the field.

Abstract Solar‐driven vapor generation technology can directly produce clean water, but existing strategies remain challenging in achieving both high evaporation performance and good salt resistance due to complex water‐thermal management. Here, we constructed hydrogel‐based hierarchically nanostructured evaporator (HNE) with vertically aligned micro water transportation pathways and water confined ion selective nanochannels. Based on the polarity modified hierarchical structures and umbrella‐shaped geometry design, HNEs can achieve high‐speed water transfer at low saturated water content to realize efficient heat energy confinement, and provide more heat exchange sites. Consequently, an exciting water evaporation rate of 3.68 kg m−2 h−1 and the efficiency of 91.1% were achieved under 1 sun solar radiation. More importantly, the overlapping electrical double layer in the narrow nanochannels endows the ions selectivity of the nanochannel to reject anions, resulting in reliable long‐term salt resistance. The ingenious design was creatively confirmed by streaming potential and validated during long‐term efficient work.

Wetting has been studied in various fields: chemical industry, automobile manufacturing, food companies, and even life sciences. In these studies, super-hydrophobic surfaces have been achieved through complex steps and processes. To realize super-hydrophobicity, however, we demonstrated a simple and single pass laser process for the fabrication of micro/nano hierarchical structures on the flexible polytetrafluoroethylene (PTFE, Teflon) surface. The fabricated hierarchical structures helped increase the hydrophobicity by augmenting the surface roughness and promoting air-trapping. In addition, we employed a low-cost and high-throughput replication process producing numerous polydimethylsiloxane (PDMS) replicas from the laser-processed PTFE film. Thanks to the anti-adhesive characteristics of PTFE and the elasticity of PDMS, the structure perfectly transferred to the replica without any mechanical failure. Moreover, our designed mesh patterns offered the possibility of large area applications through varying the process parameters (pitch, beam spot size, laser fluence, and scan speed). Even though mesh patterns had relatively large pitch (190 μm), we were able to achieve high contact angle (>150°). Through pneumatically deformed structure, we clearly showed that the shape of the droplets on our laser-processed super-hydrophobic surface was spherical. Based on these outcomes, we can expect our single laser pulse exposure process can overcome many drawbacks and offer opportunities for advancing applications of the wetting phenomena.

The process of the hydrothermal synthesis of hierarchically organized nanomaterials with the core-shell structure with the composition ((CeO2)0.8(Sm2O3)0.2)@NiO was studied, and the prospects for their application in the formation of planar composite structures using microextrusion printing were shown. The hydrothermal synthesis conditions of the (CeO2)0.8(Sm2O3)0.2 nanospheres were determined, and the approach to their surface modification by growing the NiO shell with the formation of core-shell structures equally distributed between the larger nickel(II) oxide nanosheets was developed. The resulting nanopowder was used as a functional ink component in the microextrusion printing of the corresponding composite coating. The microstructure of the powders and the oxide coating was studied by scanning (SEM) and transmission electron microscopy (TEM), the crystal structure was explored by X-ray diffraction analysis (XRD), the set of functional groups in the powders was studied by Fourier-transform infrared spectroscopy (FTIR) spectroscopy, and their thermal behavior in an air flow by synchronous thermal analysis (TGA/DSC). The electronic state of the chemical elements in the resulting coating was studied using X-ray photoelectron spectroscopy (XPS). The surface topography and local electrophysical properties of the composite coating were studied using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM). Using impedance spectroscopy, the temperature dependence of the specific electrical conductivity of the obtained composite coating was estimated. [ABSTRACT FROM AUTHOR]

Many aquatic creatures in nature have non-cooperative surface scaling abilities using suction organs; micro-/nano-scale structures found in different parts of the organs play an important role in this mechanism. Synthetic bioinspired suction devices have been developed, but the mechanisms of bioinspired suction system need further investigation. This paper presents the development of a synthetic adhesive disc inspired by the hillstream loach. The microscopic structures involved in adhesion of the hillstream loach were investigated. Bioinspired suction discs were designed with single-level or hierarchical micropatterned margins. Micro three-dimensional (3D) printing and micro electromechanical system (MEMs) technology were utilized in the fabrication of the discs, and the adhesion performance was tested on substrates with different roughness values. The engaging and disengaging processes of the margin were simulated by carrying out a peeling test on a submerged substrate. The interactions between the liquid film and the microstructures were observed using fluorescence microscopy. The enhanced adhesion forces due to the synergy of the hierarchically micro-patterned margin and the disc cavity were duplicated in the synthetic adhesion system. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) printing has been widely utilized to fabricate free-standing electrodes in energy-related fields. In terms of fabrication, the two most challenging limitations of 3D printed electrodes are the poor printing resolution and simple structural dimension. Here we proposed a novel process to fabricate molybdenum disulfide-polyvinylidene fluoride (MoS2-PVDF) hierarchical electrodes for energy storage applications. The 20-layer microscale PVDF films with a stable fiber width of 8.3 ± 1.2 μm were fabricated by using electrohydrodynamic (EHD) printing. MoS2 nanostructures were synthesized and assembled on the microscale PVDF fibers by using hydrothermal crystal growth. The structural and material investigations were conducted to demonstrate the geometrical morphology and materials component of the composite structure. The electrochemical measurements indicated that the MoS2-PVDF electrodes exhibited the typical charge-discharge performance with a mass specific capacitance of 60.2 ± 4.5 F/g. The proposed method offers a facile and scalable approach for the fabrication of high-resolution electrodes, which might be further developed with enhanced specific capacitance in energy storage fields. [ABSTRACT FROM AUTHOR]

Vapor‐phase growth methods, taking the advantages of producing high‐quality crystals with low defects, thin thickness, and homogeneous composition, are of great significance in the field of organic crystal growth and their high‐performance applications. At present, the requirements for organic crystals as building blocks for the construction of optoelectronic devices are increasing with the constant advances in organic optoelectronics. Therefore, the vapor‐phase growth method would become one of the practical techniques that cannot be ignored to fabricate organic crystals. In this paper, an overview of different vapor‐phase growth methods for the preparation of organic single crystals is provided. An introduction to the current status of the vapor phase method is presented and the view on the challenges it faces with some promising solution ideas. It is believed that this review will serve as a reference for further development and an inspiration for the new way forward. [ABSTRACT FROM AUTHOR]

Alkaline electrochemical water oxidation powered by renewable energies is a promising and environmentally friendly way to produce hydrogen. The industrial water electrolyzers are commonly operated at a high current density, calling for abundant and durable active sites to participate in. The rational design of hierarchically structured electrocatalysts is thus essential to industrial water electrolyzers. Herein, we develop a Fe3+ induced nanosizing strategy for fabricating such a hierarchical FeCo LDH@Co3O4 (LDH: layered double hydroxide) nanostructure array for high-rate water oxidation. Density functional theory (DFT) simulations indicate that the introduction of Fe3+ with a small ion radius and high electrical repulsion in the LDH layer distorted the LDH layer, resulting in a reduced nanosheet size and enabling the formation of a hierarchical structure. Such structure cannot be achieved without the participation of Fe3+ cations. Benefiting from the significantly enhanced electrochemical surface areas and charge/mass transport due to the hierarchical structure together with the boosted intrinsic activity by electronic modulation of Fe3+, such FeCo LDH@Co3O4 electrode can deliver an industrial-level current density of 1,000 mA·cm−2 at a small overpotential of 392 mV for water oxidation. When assembled in a water electrolyzer, it delivers a current density of 100 mA·cm−2 at a low operation voltage of 1.61 V. Powered by solar light, the electrolyzer demonstrates high solar-to-hydrogen efficiency of 18.15% with stable and reproducible photoresponse. These results provide new insights for constructing hierarchical nanostructures for advanced water oxidation and other diverse applications. [ABSTRACT FROM AUTHOR]

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Although potassium batteries (KBs), such as potassium‐metal batteries and potassium‐ion batteries, promise low cost and high‐energy density, specialized separators are not available that can satisfy the KBs operations. In this work, a hierarchical porous cellulose (HPC) separator with high‐performance, by engineering of the natural supra‐molecular structure of cellulose, is reported. The supra‐molecular and hierarchical structure of cellulose provides the separator with high porosity, excellent mechanical properties, superior electrolyte wettability, and stable thermal performance. The incorporation of small pore size (0.64 µm) and suitable tortuosity (1.83) reveal that the separator enables uniform current distribution and inhibits the puncturing of K dendrites. Thus, a lifespan of more than 1000 h for a K//K symmetric cell is achieved without short‐circuiting. Benefiting from the high K+ transference number (0.69), graphite//K and Prussian blue (PB)//K cells with HPC separators exhibited pre‐eminent cycling stability (400 and 200 cycles, respectively) and high‐rate performance. Moreover, the PB//graphite full cell with HPC separator is shown to deliver a reversible capacity of 86 mAh g−1 with 100 cycles. This novel HPC separator provides a possibility for the sustainable development of KBs and other energy storage systems by the rational structural modification of plants. [ABSTRACT FROM AUTHOR]

Flexible pressure sensors have been extensively explored for their widespread applications in wearable electronic devices such as medical diagnosis and motion monitoring. In this paper, a facile method is adopted to prepare the ordered hierarchical structure array and then it is applied to improve the performance of capacitive flexible pressure sensors. The results indicate that the pressure sensor based on hierarchical structure array is with high sensitivity (0.382 kPa‐1), fast response and recovery time (26 and 25 ms), and its minimum detection pressure can reach 4 Pa. Besides, the sensor based on hierarchical structure array has also been successfully applied to the dynamic pulse monitoring of the neck, limb movement monitoring, and pressure monitoring in water cup grasping process, which shows high stability and reliability, demonstrating its broad application prospects. This research could provide useful guidance for the preparation and applications of high‐performance flexible pressure sensors. [ABSTRACT FROM AUTHOR]

Spinel CuBi 2 O 4 microspheres with hierarchical structures in terms of compacted nanoblocks and radial nanorods were prepared by a facile hydrothermal process without additives. The diameters of CuBi 2 O 4 microspheres were modulated in the range of 9.1–15.3 μm, while the nanoblocks and nanorods were self-assembled with increased cross-sections by extending reaction time. XRD and XPS analysis confirmed the preferable crystallization and high purity in all types of CuBi 2 O 4. N 2 adsorption and desorption determinations revealed a maximum specific surface area of 6.0512 m2g-1. The optimal sensitivity responses occurred around 240 °C as the as-prepared CuBi 2 O 4 were made into gas sensors, where formaldehyde, methanol, ethanol and ammonia were selected as tested gases. High gas selectivity and sensitivity were revealed in detecting formaldehyde, and superior reproducibility was obtained after four consecutive tests. Gas sensing mechanisms were discussed with the emphasis on hierarchical structures of CuBi 2 O 4 microspheres. [ABSTRACT FROM AUTHOR]

In this study, we focus on synthesizing various 3D ZnO hierarchical nanostructures (ZnH) for highly effective photocatalytic performance via an innovative sol-gel method using diethylene glycol as an assembly-guiding agent. The morphology of 3D ZnH can be turned from nanospheres into nanoplate blocks and nanosheet-based flowers by increasing the concentration of diethylene glycol. Possible growth mechanisms are proposed for different assembly architectures. Analysis of characterization techniques reveal that the synthesized hierarchical structures exhibited a large specific surface area, high degree of crystallinity, and a band gap in the range 2.95–3.11 eV, depending on their morphology. X-ray photoelectron and photoluminescence spectroscopy revealed the presence of rich oxygen vacancies introduced by the 3D ZnO hierarchical morphology. The photodegradation experiment results presented in ZnO nanosheet-based flower shown superior photoactivity of rhodamine B degradation compared with nanospheres and nanoplate blocks structures. This is attributed to the larger surface area, enhanced light absorption, and more effective photogenerated charge separation on account of their rich Vo. The establishment of relevant structural–optical property relationships is expected to provide deeper insights into the potential use of ZnH for innovative devices. Highlights: Three different 3D ZnO hierarchical nanostructures were successfully synthesized. The morphology-optical properties relationship of the obtained samples was studied. Optical properties and oxygen defects are dependent on 3D ZnO hierarchical morphology. The ZnO nanosheet-based flowers exhibit excellent photocatalytic activity. [ABSTRACT FROM AUTHOR]

Over the past decades, considerable efforts have been made to develop hierarchically porous electrodes for the high surface area, the fast velocity of fuels/products to/away from the reaction site, and the high loading of thermal‐ and/or electrochemical‐ catalysts. Manipulation of the hierarchical structure is one of the key steps for high performance in applications of efficient energy storage and conversion such as solid oxide cells. This review starts with a brief introduction to the basic concept of mass transport and how mass transport may affect performance. Then, the latest developments in enhancing the performance of cells through modification or optimization of the hierarchically porous electrode structures, including altering the geometry or morphology and increasing the triple‐phase boundaries length of electrodes are summarized. Subsequently, the unique characteristics of microstructures that are critical to enhancing electrode performance and provide important insights into the mechanisms of performance (activity and durability) enhancement, aiming at achieving the rational design of better electrode architecture are highlighted. Finally, the remaining challenges for the knowledge‐based design of highly efficient electrodes for electrochemical devices, together with possible directions and future perspectives for the development of highly efficient electrodes through optimization of microstructure are discussed. [ABSTRACT FROM AUTHOR]

The present‐day ubiquity of smart devices used under extreme conditions demands robust and more sustainable energy storage. Therefore, lightweight electrodes with both excellent electrochemical and mechanical performance to meet these needs are of great importance. Moreover, the recycling of current energy storage devices poses significant environmental concerns, a particularly daunting prospect given the increasing waste volume of metal‐based electrodes. To that end, these challenges of performance and sustainability are addressed by leveraging accessible digital light processing (DLP) technology and tailored post‐process heat treatment to fabricate a metal‐based 3D substrate with ultrahigh precision and hierarchical porosity. Here, a 4‐mm‐thickness metal‐based electrode with NiCo2S4 loading of 18.38 mg cm–2 achieves a high areal capacity of 7.327 mA h cm–2 at 44.85 mA cm–2, providing a promising way to fabricate high‐performance thick electrodes. Most importantly, these electrodes can be fabricated from recyclable metal salt feedstock. The geometric freedom offered by 3D printing supplemented by finite element analyses allows for optimized complex structures to be fabricated. Through rational design realized by 3D printing, a desirable compromise between building density, mechanical properties, electrochemical performances, and environment‐friendly processing cycle can be arrived upon. [ABSTRACT FROM AUTHOR]

A two-stage micromechanics technique is used to predict the elastic modulus, as well as the major and minor Poisson's ratio of unidirectional natural fiber (NF) reinforced composites. The actual NF microstructure consists of cellulose, hemicellulose, lignin, lumen, etc., and these constituents and their contributions are neglected in classical models while quantifying their mechanical properties. The present paper addresses the effect of the real microstructure of the natural jute fiber (JF) by applying a micromechanics approach with the Finite Element Method. Six different hierarchically micro-structured JFs are considered to quantify the JF elastic properties in the first level of homogenization. Later, the JF reinforced polypropylene matrix properties are investigated in the second stage by adopting a homogenization approach. Taking into account the different hierarchical structures (HS), the fiber direction modulus (E1), transverse modulus (E2 and E3), in-plane and out-of-plane shear modulus (G12 and G23), and major (ν12, ν13) and minor (ν23, ν21) Poisson's ratios are estimated for JF and JF reinforced polypropylene composites. The predicted elastic modulus from micromechanics models is validated against the analytical results and experimental predictions. From the present work, it is observed that the HS of NF needs to be considered while addressing the elastic properties of the NF-reinforced composite for their effective design, particularly at a higher volume fraction of NF. [ABSTRACT FROM AUTHOR]

Microstructure of the high nitrogen heat‐resistant martensitic steel (HNHM) crept using 140–170 MPa loading stresses at 923 K is investigated in correlation with creep lifetime and creep rupture strength. Upon creep deformation, both recrystallized grains and the preexisted hierarchical structures grow via strain‐induced boundaries migration (SIBM) induce the degradation of strengthening. For preexisted hierarchical structures in HNHM, martensitic packets and blocks are more inclined to form at higher stresses (170 MPa), causing the degradation of strength, while laths retain easily at lower stresses (140–155 MPa), retarding the creep damage. Additionally, under all stresses and upon 923 K, the highly stabilized MN precipitates not only pin the hierarchical structural boundaries effectively, but also act as the core for the nucleation of Laves, realizing strengthening. The findings elucidate the coupling contribution of hierarchical structures and MN‐type precipitates on the creep strengthening for HNHMs, challenging the common viewpoint that the coupling coarsening of lath and precipitates dominates the degradation of strengthening, and thus, deepens the understanding of the creep resistance of the HNHM and provides the first insights into obtaining reliable predicted creep life of the novel HNHMs. [ABSTRACT FROM AUTHOR]

The intrinsic poor conductivity and large volume variation of ferric silicate severely hinder its practical application. Herein, a unique double‐shell‐structured amorphous porous carbon@ferric silicate hierarchical hollow sphere (PC@FS) is designed to improve its electrochemical performance. The amorphous feature of PC@FS is favorable for Li+/Na+ diffusion and avoids the structure collapse. FS nanosheets shorten the transport path of lithium/sodium ions. The hollow carbon spheres not only boost the conductivity but also accommodate volume variation. Besides, the heterointerface of PC@FS exhibits interfacial lithium/sodium storage. The synergistic effects bestow PC@FS enhanced lithium and sodium storage with high reversible capacity, excellent rate performance, and remarkable cycling stability. It manifests a capacity as high as 625.7 mAh g−1 at 5 A g−1 after 1000 cycles for lithium‐ion batteries and 315.7 mAh g−1 at 0.05 A g−1 after 50 cycles for sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Biomaterial-based solar-driven evaporation has great potential for wastewater treatment and seawater desalination with a high energy conversion and utilization efficiency. However, technology gaps still exist for effectively and directly applying multiscale structures and intrinsic water transport channels of natural materials to enhance high-efficiency photothermal evaporation. In this study, a high-performance biomass-derived photothermal evaporative material was obtained using Salvinia natans , a common aquatic floating plant, together with simple poly( m -phenylenediamine) oxidation modification, building a hybrid biomass evaporator. With advantageous natural features of adequate water transport, microscale-nanoscale hierarchical structures, effective water activation, and antisalt-fouling function, the hybrid biomass evaporator achieves a high evaporation rate of 2.24 kg m -2 h -1 under one sun radiation (1 kW m -2 ). In addition, modified Salvinia natans also demonstrate certain ability to remove heavy metals during the photothermal evaporation of wastewater. This work offers a new perspective on the synthesis of an environmentally friendly and cost-effective solar-driven evaporator material, which has the advantages of low cost, simple process, and high photothermal conversion efficiency, and can be widely applied to seawater desalination and the treatment of wastewater with high salt concentrations.

The nacre-inspired multi-nanolayer structure offers a unique combination of advanced mechanical properties, such as strength and crack tolerance, making them highly versatile for various applications. Nevertheless, a significant challenge lies in the current fabrication methods, which is difficult to create a scalable manufacturing process with precise control of hierarchical structure. In this work, a novel strategy is presented to regulate nacre-like multi-nanolayer films with the balance mechanical properties of stiffness and toughness. By utilizing a co-continuous phase structure and an extensional stress field, the hierarchical nanolayers is successfully constructed with tunable sizes using a scalable processing technique. This strategic modification allows the robust phase to function as nacre-like platelets, while the soft phase acts as a ductile connection layer, resulting in exceptional comprehensive properties. The nanolayer-structured films demonstrate excellent isotropic properties, including a tensile strength of 113.5 MPa in the machine direction and 106.3 MPa in a transverse direction. More interestingly, these films unprecedentedly exhibit a remarkable puncture resistance at the same time, up to 324.8 N mm -1 , surpassing the performance of other biodegradable films. The scalable fabrication strategy holds significant promise in designing advanced bioinspired materials for diverse applications., (© 2024 Wiley‐VCH GmbH.)

The calcareous skeletons built by invertebrate organisms share a paradoxical property. Although growing outside the mineralizing cell layers the crystal-like skeleton units exhibit morphologies and three-dimensional arrangements that imply an efficient link between crystallization process and taxonomy. Almost two centuries of investigation led to a series of developmental models in which biological and physical or chemical influences are variously balanced. Recent innovative methods allow for their re-examination. From control of the overall shape of the shell to photo-spectroscopic evidence at the atomic level, influence of the biological processes on mineral properties may be a widely shared specificity of the calcareous biomineralization mechanism.

Burn injuries are very common due to heat, accidents, and fire. Split-thickness skin grafting technique is majorly used to recover the burn sites. In this technique, the complete epidermis and partial dermis layer of the skin are used to make grafts. A small amount of skin is passed into the mesher to create an incision pattern for higher expansion. These grafts are transplanted into the burn sites with the help of sutures for recovering large burn areas. Presently, the maximum expansion possible with skin grafting is very less (

Derived from the increasing demand for radar and infrared camouflage integration, a two‐layer hierarchical structure that combines coating and a square patch‐based metasurface is designed. Under deep subwavelength thickness, the infrared stealth layer (IRSL) can markedly reinforce microwave absorption layer (MAL) performance. More than 90% of the electromagnetic wave energy in the 3.7–5.1 GHz and 12.8–18 GHz bands can be absorbed. The hierarchical structure expands the effective absorption bandwidth of the exposed coatings from 0 to 6.6 GHz, and the maximum reflection loss increases from −8 to −40 dB. Moreover, the emissivity in the midinfrared range is maintained at an extremely low value of 0.281. The delay of magnetic resonance is found in the simulation model, indicating that strong magnetic resonance is formed in coatings after covering the IRSL. Meanwhile, the absorption peaks of the coatings are controlled by low‐pass filter metasurfaces. These two factors contribute to the enhancement effect of IRSL on MAL and break the boundary between radar and infrared stealth. Herein, an original solution for tuning multispectral electromagnetic (EM) waves is provided and it has broad application prospects in advanced compatible camouflage material. [ABSTRACT FROM AUTHOR]

Stabilizing the hydrophobic wetting state on a surface is essential in heat transfer and microfluidics. However, most hydrophobic surfaces of Si are primarily achieved through microtexturing with subsequent coating or modification of low surface energy materials. The coatings make the hydrophobic surface unstable and impractical in many industrial applications. In this work, the Si chips' wettability transitions are yielded from the original hydrophilic state to a stable transitional hydrophobic state by texturing bamboo-leaf-like hierarchical structures (BLHSs) through a diamond grinding wheel with one-step forming. Experiments showed that the contact angles (CAs) on the BLHS surfaces increased to 97° and only reduced by 2% after droplet impacts. This is unmatched by the current texturing surface without modification. Moreover, the droplets can be split up and transferred by the BLHS surfaces with their 100% mass. When the BLHS surfaces are modified by the low surface energy materials' coating, the hydrophobic BLHS surfaces are upgraded to be superhydrophobic (CA > 135°). More interestingly, the droplet can be completely self-sucked into a hollow micro-tube within 0.1 s without applying external forces. A new wetting model for BLHS surfaces based on the fractal theory is determined by comparing simulated values with the measured static contact angle of the droplets. The successful preparation of the bamboo-leaf-like Si confirmed that transitional wettability surfaces could be achieved by the micromachining of grinding on the hard and brittle materials. Additionally, this may expand the application potential of the key semiconductor material of Si. [ABSTRACT FROM AUTHOR]

The calcareous skeletons built by invertebrate organisms share a paradoxical property. Although growing outside the mineralizing cell layers the crystal-like skeleton units exhibit morphologies and three-dimensional arrangements that imply an efficient link between crystallization process and taxonomy. Almost two centuries of investigation led to a series of developmental models in which biological and physical or chemical influences are variously balanced. Recent innovative methods allow for their re-examination. From control of the overall shape of the shell to photo-spectroscopic evidence at the atomic level, influence of the biological processes on mineral properties may be a widely shared specificity of the calcareous biomineralization mechanism. [ABSTRACT FROM AUTHOR]

High strength, toughness, and conductivity are among the most sought‐after properties of flexible electronics. However, existing engineering materials find it difficult to achieve both excellent mechanical properties and high conductivity. To address this challenge, this study proposes a facile yet versatile strategy for preparing super‐tough conductive organo‐hydrogels via freeze‐casting assisted solution substitution (FASS). This FASS strategy enables the formation of organo‐hydrogels in one step with exquisite hierarchical anisotropic structures coupled with synergistic strengthening and toughening effects across multiple length scales. As an exemplary material, the prepared polyvinyl alcohol (PVA) organo‐hydrogel with solvent content up to 87 wt% exhibits a combination of high strength (6.5 MPa), high stretchability (1710% in strain), ultra‐high toughness (58.9 MJ m−3), as well as high ionic conductivity up to 6.5 S m−1 with excellent strain sensitivity. The exceptional combination of mechanical properties and conductivity makes the PVA organo‐hydrogel a promising flexible electronics material. In addition, the FASS strategy can also endow hydrogels with multi‐functions, including thermo‐healability, freezing tolerance and shape recoverability, and can be applied to various hydrogel materials, such as carboxymethyl cellulose, sodium alginate, and chitosan. Hence, this work provides an all‐around solution for preparing advanced strong and tough conductive soft materials for a multitude of applications. [ABSTRACT FROM AUTHOR]

Various models of synthetic cells have been developed as researchers have sought to explore the origins of life. Based on the fact that structural complexity is the foundation of higher‐order functions, this review focuses on hierarchical structures in synthetic cell models that are inspired by living systems, in which macromolecules are the dominant participants. The underlying advantages and functions provided by biomimetic higher‐order structures are discussed from four perspectives, including hierarchical structures in membranes, in the composite construction of membrane‐coated artificial cytoplasm, in organelle‐like subcellular compartments, as well as in synthetic cell–cell assembled synthetic tissues. In parallel, various feasible driving forces and approaches for the fabrication of such higher‐order structures are showcased. Furthermore, both the implemented and potential applications of biomimetic systems, bottom‐up biosynthesis, biomedical tissue engineering, and disease therapy are highlighted. This thriving field is gradually narrowing the gap between fundamental research and applied science. [ABSTRACT FROM AUTHOR]

Hierarchical wrinkling is a buckling-based low-cost technique for fabrication of complex microstructures over large areas. However, predicting and fabricating the desired microstructures is challenging due to the underlying nonlinear mechanics. Although computational predictive tools based on finite elements analysis (FEA) are available, these are impractical for inverse design, i.e., for the prediction of inputs that would generate the desired wrinkles. This is because one must resort to slow and resource-intensive iterations to predict the inputs. Here, we present a prediction technique that is based on machine learning (ML) to overcome this limitation. Our technique comprises: (i) capturing the predictive capability of FEA through computationally-efficient surrogate ML models, (ii) applying the models to map the feasible input design space into the outputs, i.e., the predicted wrinkles, and (iii) searching through the predicted wrinkles for the desired microstructure. We have validated our technique against FEA simulations and have demonstrated its utility by rapidly identifying the inputs that would generate desired hierarchical wrinkles including flat-top sinusoidal patterns. Our approach shortens the exploration and comparison of a million design choices from more than ten days to less than a minute. It can therefore significantly mature wrinkling into a scalable manufacturing process for optics, sensing, and surface texturing applications. [Display omitted] • Predicting the inputs for the desired hierarchical wrinkles is challenging. • Computationally-efficient surrogate models developed using machine learning (ML). • Neural network-based ML models were trained using physics-based finite element simulations. • ML models expedite design exploration of a million choices by more than 10,000 times. • Technique validated by identifying inputs for two target wrinkled microstructures. [ABSTRACT FROM AUTHOR]

Three‐dimensional (3D) hierarchical structures have been explored for various applications owing to the synergistic effects of micro‐ and nanostructures. However, the development of spherical micro/nano hierarchical structures (S‐HSs), which can be used as energy/water harvesting systems and sensing devices, remains challenging owing to the trade‐off between structural complexity and fabrication difficulty. This paper presents a new strategy for facile, scalable S‐HS fabrication using a thermal expansion of microspheres and nanopatterned structures. When a specific temperature is applied to a composite film of microspheres and elastomers with nanopatterned surfaces, microspheres are expanded and 3D spherical microstructures are generated. Various nanopatterns and densities of spherical microstructures can thereby be quantitatively controlled. The fabricated S‐HSs have been used in renewable electrical energy harvesting and sustainable water management applications. Compared to a triboelectric nanogenerator (TENG) with bare film, the S‐HS‐based TENG exhibited 4.48 times higher triboelectric performance with high mechanical durability. Furthermore, an S‐HS is used as a water harvesting device to capture water in a fog environment. The water collection rate is dramatically enhanced by the increased surface area and locally concentrated vapor diffusion flux due to the spherical microstructures. [ABSTRACT FROM AUTHOR]

Hierarchical porous polymer particles (HPPPs) from the assembly of polymer chains have attracted increasing interest because of their prospective applications in drug delivery and catalysis. This work utilized a blending strategy of polymer mixture in mixed solvents to fabricate HPPPs with adjustable pore structures. Firstly, using methacrylic acid (MAA) and methyl methacrylate (MMA) with a precise ratio, a copolymer solution of P(MMA‐MAA) was prepared in a mixed solvent of ethanol and water. Then, styrene (St) was added stepwise along with polymerization for achieving a translucent polymer mixture. Further, a quantitative amount of the polymer mixture and six‐fold volume of water were rapidly mixed with vortex oscillation. The HPPPs were formulated eventually by the assembly of hydrophilic P(MMA‐MAA) copolymers and hydrophobic PSt homopolymers, as well as micelles comprised of P(MMA‐MAA) copolymer and low‐polarity solvent. The size and number of nanopores were effectively regulated by the solvent polarity, polymerization temperature and monomer ratios. Moreover, the resultant HPPPs exhibited a hierarchical porous structure, having broad application in biomedical and environmental sciences. © 2022 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

Electrospinning is a popular method for generating long and continuous nanofibers due to its simplicity and versatility. However, conventional electrospun products have weak strength and low availability, which restrict their functionality in complex applications. Hierarchical morphology introduces additional and distinctive structural layers onto electrospun fibers. This requires either an extra fabrication step or controlling electrospinning parameters to achieve the desired morphology. Hierarchical morphology can improve the properties of electrospun nanofibers while also mitigating the undesired characteristics. This review discusses the primary and secondary hierarchical structures of electrospun nanomaterials. Hierarchical structures were found to enhance the functionality of nanomaterials and improve pore connectivity and surface areas of electrospun nanofibers. A further advantage is the ability to impart multiple functionalities on nanostructures. With a better understanding of some of the dominant hierarchical structures, nanomaterials applications in drug delivery, tissue engineering, catalysis, and energy devices industries can be improved.