Three-dimensional Hierarchical Structure Research Articles

An inspiration from the microstructure of the cortical bone in goat tibia

When vigorous goats are running and jumping, their leg bones play a crucial role in dynamic loading. The hierarchical structure of diverse tissues at different length scales is commonly used to account for the superior mechanical properties of bone. Yet, how the goat tibia achieves its remarkable function remains mostly unknown. Scanning electron microscopy was employed to image the multi-scale microstructure of the cortical bone in goat tibia. A new processing method was utilized during the preparation of one of the three kinds of samples. The transverse and longitudinal sections of the cortical bone were observed thoroughly, and high-quality images of the internal organizations are acquired. Some interesting findings, including the two-layered character of cortical bone and the microstructure near osteocyte lacunae, are discussed. A three-dimensional three-level hierarchical structure is found accordingly. Then, the cushioning mechanisms are discussed by analyzing the structure–function relationships of the bone tissues. Finally, a structural model of biomimetic composite is proposed based on the authors’ insights into the constitution of cortical bone, which is expected to inspire engineers to design load-bearing structures with excellent mechanical performance.

Three-dimensional Hierarchical Structure NiFe Layered Double Hydroxides Nanosheets Based on Carbon Cloth for High Performance Non-Enzymatic Glucose Detection

Three-dimensional Hierarchical Structure NiFe Layered Double Hydroxides Nanosheets Based on Carbon Cloth for High Performance Non-Enzymatic Glucose Detection

Removal of heavy metals from soil by vermiculite supported layered double hydroxides with three-dimensional hierarchical structure

Vermiculite supported Mg-Al layered double hydroxide (LDH@VMT) with three-dimensional hierarchical structure was successfully synthesized and the removal performance of LDH@VMT in soil was investigated for heavy metals removal (Cu2+, Pb2+, Zn2+ and Ni2+). Kinetics studies of heavy metals removal were well described by intraparticle diffusion and pseudo-second-order model. Adsorption isotherm data of Cu2+ and Pb2+ yielded a better accordance of Freundlich model, however, data of Zn2+ and Ni2+ were fitted Langmuir model well. Moreover, the different mechanisms of heavy metals removal by precipitation (Cu2+, Pb2+) and isomorphous replacement (Zn2+, Ni2+) were investigated and proposed, respectively. The effect of coexistence cations and column leaching experiments for practical performance assessment were also examined. The excellent removal performance suggested a promising strategy in heavy metals contaminated soil.

Direct Growth of Flower-Shaped Cos1.097 Nanoflakes on Flexible Carbon Cloth: An Ultrastable Cycle Durability Anode for Reversible Sodium Storage

It is highly attractive for constructing CoSx-based electrode architectures in sodium ion batteries (SIBs). For the first time, a three-dimensional flower-shaped CoS1.097 nanoflakes grown on carbon cloth is developed and examined as flexible anode configuration for SIBs, showing a large discharge capacity of 835.7 mAh g-1 at 0.1 A g-1 and ultrastable lifetime of 1000 cycles at 5 A g-1. The superior sodium storage capability can be attributed to the unique flexible electrode with connected three-dimensional hierarchical porous structure, which makes for ensuring good electrical connection, sustaining the structural integrity of electrode and facilitating fast ion diffusion kinetics upon cycling

Construction of ZnO/CdS three-dimensional hierarchical photoelectrode for improved photoelectrochemical performance

Three-dimensional ZnO/CdS hierarchical films with uniform CdS deposition on the ZnO nanorods surface is prepared by a two-step hydrothermal method. The morphology of CdS nanostructure can be adjusted from particles to sheets and then blocks by changing amount of the surfactant in the precursor solution. The ZnO/CdS hierarchical film as photoelectrode with optimized morphology shows significant enhancement to the light harvesting and photoelectrochemical performance. Under light irradiation of 100 mW/cm2, the three-dimensional ZnO/CdS hierarchical film yields a photocurrent density of 4.5 mA/cm2, approximately two times higher than that of film without three-dimensional structure. The photoelectrochemical property improvement is attributed to the (1) enhanced light absorption due to the multi-scattering and multi-reflection of the unique three-dimensional hierarchical structure, (2) improved photogenerated carrier separation and transportation because of the hierarchical and heterojunction structure, and (3) facilitated hole transfer and reaction at the photoelectrode-electrolyte interface due to the large surface area.

Purposely Designed Hierarchical Porous Electrodes for High Rate Microbial Electrosynthesis of Acetate from Carbon Dioxide.

Carbon-based products are crucial to our society, but their production from fossil-based carbon is unsustainable. Production pathways based on the reuse of CO2 will achieve ultimate sustainability. Furthermore, the costs of renewable electricity production are decreasing at such a high rate, that electricity is expected to be the main energy carrier from 2040 onward. Electricity-driven novel processes that convert CO2 into chemicals need to be further developed. Microbial electrosynthesis is a biocathode-driven process in which electroactive microorganisms derive electrons from solid-state electrodes to catalyze the reduction of CO2 or organics and generate valuable extracellular multicarbon reduced products. Microorganisms can be tuned to high-rate and selective product formation. Optimization and upscaling of microbial electrosynthesis to practical, real life applications is dependent upon performance improvement while maintaining low cost. Extensive biofilm development, enhanced electron transfer rate from solid-state electrodes to microorganisms and increased chemical production rate require optimized microbial consortia, efficient reactor designs, and improved cathode materials. This Account is about the development of different electrode materials purposely designed for improved microbial electrosynthesis: NanoWeb-RVC and EPD-3D. Both types of electrodes are biocompatible, highly conductive three-dimensional hierarchical porous structures. Both chemical vapor deposition (CVD) and electrophoretic deposition were used to grow homogeneous and uniform carbon nanotube layers on the honeycomb structure of reticulated vitreous carbon. The high surface area to volume ratio of these electrodes maximizes the available surface area for biofilm development, i.e., enabling an increased catalyst loading. Simultaneously, the nanostructure makes it possible for a continuous electroactive biofilm to be formed, with increased electron transfer rate and high Coulombic efficiencies. Fully autotrophic biofilms from mixed cultures developed on both types of electrodes rely on CO2 as the sole carbon source and the solid-state electrode as the unique energy supply. We present first the synthesis and characteristics of the bare electrodes. We then report the outstanding performance indicators of these novel biocathodes: current densities up to -200 A m-2 and acetate production rates up to 1330 g m-2 day-1, with electron and CO2 recoveries into acetate being very close to 100% for mature biofilms. The performance indicators are still among the highest reported by either purposely designed or commercially available biocathodes. Finally, we made use of the titration and off-gas analysis sensor (TOGA) to elucidate the electron transfer mechanism in these efficient biocathodes. Planktonic cells in the catholyte were found irrelevant for acetate production. We identified the electron transfer to be mediated by biologically induced H2. H2 is not detected in the headspace of the reactors, unless CO2 feeding is interrupted or the cathodes sterilized. Thus, the biofilm is extremely efficient in consuming the generated H2. Finally, we successfully demonstrated the use of a synthetic biogas mixture as a CO2 source. We thus proved the potential of microbial electrosynthesis for the simultaneous upgrading of biogas, while fixating CO2 via the production of acetate.

Deep eutectic solvents assisted synthesis of MgAl layered double hydroxide with enhanced adsorption toward anionic dyes

The chloride (Cl−)-intercalated MgAl layered double hydroxide (LDH) with a three-dimensional (3D) hierarchical structure was synthesized via a one-step solvothermal method based on deep eutectic solvents (DESs) including MgCl2·6H2O/urea (molar ratio of 1:2) and AlCl3·6H2O/PEG 200 (molar ratio of 1:3). The as-prepared Mg2Al-Cl LDH acquired high uptake capacities (1051.87, 889.76 and 512.55 mg g-1) for the anionic dyes of methyl orange (MO), congo red (CR) and indigo carmine (IC) at 25 °C, which are much higher than those of most reported LDHs in the literature. These high uptake capacities are not only associated with electrostatic attraction and hydrogen bonding, but also related to ion exchange between Cl− and dye molecules. The adsorption kinetics for all studied dyes were well-fitted to the pseudo-second order kinetic model well (R2 = 0.999), and the adsorption isotherms all conformed well to the Langmuir isotherm model (R2 > 0.97). Thermodynamic studies indicated that the adsorption process was endothermic in nature. In a word, the LDH was prepared with DESs using a directive and effective strategy to achieve the desirable Cl− intercalation and reduction of the CO32− contamination, which makes the adsorption rapid and highly effective for anionic dyes. Particularly, its micrometre-scale structure facilitates its separation from water, giving it extensive application prospect in wastewater treatment.

Fabricated superhydrophobic three-dimensional rambutan-like-β-NiOOH @sponge skeletons for multitasking oil–water separation

In this paper, oleophilic and superhydrophobic sponges were successfully constructed via a one-pot low temperature hydrothermal method anchoring three-dimensional rambutan-like-β-NiOOH microspheres into sponge skeletons and lauric acid modification. The constructed modified three-dimensional rambutan-like-β-NiOOH @sponge (the static contact angle of 153.5°) possessed outstanding oil sorption capacity (separation efficiency is nearly 99%) towards the various organics/oils and excellent recyclability after 30 cycles of adsorption-squeezing. Importantly, modified three-dimensional rambutan-like-β-NiOOH @sponge is capable of separating surfactant-stabilized water-in-oil emulsions and can be utilized for continuous oil-water separation with the aid of a peristaltic pump. This is mainly due to the fact that the three-dimensional hierarchical rambutan-like micronano structure formed by self-assembly with high specific surface area provides a large number of hydrophobic interfaces to improve the hydrophobic properties of sponges. This work presents a new strategy for the designs multitasking oil-water separation materials.

Carbon nanotubes modified CoZn/C composites with rambutan-like applied to electromagnetic wave absorption

The preparation of magnetic metal/carbon composites by pyrolysis of metal organic framework (MOFs) have great potential in lightweight electromagnetic (EM) wave absorption. Nevertheless, it is of great significance to design the three-dimensional (3D) hierarchical structure with synergistic effect from unique MOFs for enhancing the EM wave absorption performance. More importantly, through pyrolysis of MOF, the uniform distribution of magnetic metal and carbon material can be controlled. Herein, Co/Zn-MOF-11 microspheres are used as a precursor pyrolyzed in argon atmosphere to prepare 3D hierarchical rambutan-like bimetallic/carbon@carbon nanotubes (RBC@CNTs) composites. The RBC@CNTs composite pyrolyzed at 800 °C exhibits excellent EM wave absorption performance due to the unique structure and multiple loss mechanisms. A maximum reflection loss of −49.8 dB at 13.6 GHz can be achieved when the filler loading of 3D hierarchical RBC@CNTs composite is 20 wt% with the thickness of 2.4 mm. In addition, the effective absorption bandwidth achieves 5.5 GHz (RL ≤ −10 dB). This strategy to synthesis a unique hierarchical structure is instrumental in enhancing the attenuation of EM wave.

Three-dimensional hierarchical porous carbon structure derived from pinecone as a potential catalyst support in catalytic remediation of antibiotics.

In this study, pinecone was converted via two stage pyrolysis to produce low cost activated carbon. Furnace pyrolysis was used in the first step to convert pinecone to carbonized material, followed by microwave pyrolysis of the carbonized material activated with KOH to obtain activated carbon (ACK) materials as a suitable catalyst support. The ACK samples were characterized by their morphology, structural, adsorption and electrochemical properties. The optimized ACK 2.24-16 prepared from the pinecone had a complex three-dimensional (3D)-hierarchical porous structure, with an abundance of micropores and mesopores compared to other ACK samples judging from the high iodine number (1900 mg g−1) and the methylene blue number (4000 mg g−1) capacity. The optimized ACK 2.24-16 had the highest current response and least charge transfer resistance, along with moderate surface area (427 m2 g−1) as a promising photocatalyst support. The 3D hierarchical porous ACK significantly assisted catalyst dispersion, and enhanced visible light absorption and fast interfacial charge transfer. This work shows the promising aspect of utilizing pinecone to produce a low-cost photocatalyst support for environmental remediation.

Synthesis of Sn1-xCoxO2-δ nanostructures: Morphology and ferromagnetism

The Sn1-xCoxO2-δ nanostructures have been synthesized via a simple hydrothermal process without using any surfactants. They are assembled from low-dimensional building blocks in the form of three-dimensional hierarchical structures. Neither segregated secondary phases nor the Co-rich clusters were detected. The Sn0.94Co0.06O2-δ nanostructures exhibit the largest saturation magnetization at room temperature in the synthesized series. One of the reasons for the enhancement of room-temperature ferromagnetism is an anisotropic growth of crystals in the presence of Co (II) ions.

Synthesis and gas sensing properties of WS2 nanocrystallites assembled hierarchical WS2 fibers by electrospinning

A gas sensor based on a hierarchical WS2 structure embedded with vertically aligned WS2 nanocrystallites was demonstrated. The three-dimensional (3D) hierarchical structure provides many edge sites of nanocrystallites and an extremely large gas contact volume, resulting in a high gas response. The decreased contact resistance between the 3D hierarchical WS2 fibers and sensor electrode resulted in improved NO2 response. We fabricated a one-dimensional (1D) conductive WS2 fiber using a two-step annealing process under sulfur flow (sulfurization). It delivers a continuous and conductive carrier path and lowers the potential barrier at the interface of the WS2 nanocrystallites (top) and electrospun WS2 fiber (bottom), resulting in an improved gas response. We developed 3D hierarchical WS2 fibers embedded with vertically aligned WS2 nanocrystallites to increase the gas adsorption site in comparison with that of 1D WS2 fibers without WS2 flakes. Vertically aligned WS2 nanocrystallites were formed after a two-step annealing treatment. Sensors based on the 3D hierarchical WS2 fibers embedded with WS2 flakes, showed higher response to NO2 gas in comparison to that of pure WS2 fibers without WS2 flakes.

3D Hierarchically Structured CoS Nanosheets: Li+ Storage Mechanism and Application of the High-Performance Lithium-Ion Capacitors.

Lithium-ion capacitors possess excellent power and energy densities, and they can combine both of those advantages from supercapacitors and lithium-ion batteries, leading to novel generation hybrid devices for storing energy. This study synthesized one three-dimensional (3D) hierarchical structure, self-assembled from CoS nanosheets, according to a simple and efficient manner, and can be used as an anode for lithium ion capacitors. This CoS anode, based on a conversion-type Li+ storage mechanism dominated by diffusion control, showed a large reversible capacity, together with excellent stability for cycling. The CoS shows a discharge capacity ≈434 mA h/g at 0.1 A/g. The hybrid lithium-ion capacitor, which had the CoS anode as well as the biochar cathode, exhibits excellent electrochemical performance with ultrahigh energy and power densities of 125.2 Wh/kg and 6400 W/kg, respectively, and an extended cycling life of 81.75% retention after 40 000 cycles. The CoS with self-assembled 3D hierarchical structure in combination with a carbon cathode offers a versatile device for future applications in energy storage.

Rational Design of Novel Efficient Palladium Electrode Embellished 3D Hierarchical Graphene/Polyimide Foam for Hydrogen Peroxide Electroreduction.

The electrocatalytic applications of traditional polyimide film and carbon nanomaterials are hindered due to a shortage of three-dimensional hierarchical conductivity and porous structure. Herein, a novel polyimide-based electrode based on a highly efficient palladium nanocatalyst embellished three-dimensional reduced graphene oxide/polyimide foam (Pd/3D RGO@PI foam, signed PRP) toward H2O2 electroreduction was designed and prepared through thermal foaming procedure, followed by facile dip-drying method and electrodeposition. As expected, such a binder-free, 3D hierarchical structure PRP electrode presented high catalytic property, good stability, as well as low activation energy toward H2O2 electroreduction during the electrochemical measurement period. The PRP electrode showed a reduction current density of 810 mA·cm-2 at -0.2 V (vs Ag/AgCl) in 2.0 mol·L-1 H2SO4 and 2.0 mol·L-1 H2O2. Moreover, the PRP electrode also illustrated good reproducibility and repeatability. Reproducibility presented almost 95.8% of the initial current density after 1000 cycles test. Also, the activation energy of H2O2 electroreduction on 3D PRP electrode was 21.624 kJ·mol-1. Benefiting from the 3D hierarchical structure and efficient catalyst, the PRP electrode exhibited excellent electrocatalytic performance and was considered to be a potential candidate material for fuel cells.

Three-Dimensional Hierarchical Porous Nanotubes Derived from Metal-Organic Frameworks for Highly Efficient Overall Water Splitting.

SummaryEffective design of bifunctional catalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important but remains challenging. Herein, we report a three-dimensional (3D) hierarchical structure composed of homogeneously distributed Ni-Fe-P nanoparticles embedded in N-doped carbons on nickel foams (denoted as Ni-Fe-P@NC/NF) as an excellent bifunctional catalyst. This catalyst was fabricated by an anion exchange method and a low-temperature phosphidation of nanotubular Prussian blue analogue (PBA). The Ni-Fe-P@NC/NF displayed exceptional catalytic activity toward both HER and OER and delivered an ultralow cell voltage of 1.47 V to obtain 10 mA cm−2 with extremely excellent durability for 100 h when assembled as a practical electrolyser. The extraordinary performance of Ni-Fe-P@NC/NF is attributed to the abundance of unsaturated active sites, the well-defined hierarchical porous structure, and the synergistic effect between multiple components. Our work will inspire more rational designs of highly active non-noble electrocatalysts for industrial energy applications.

Alcohol-Induced Synthesis of Photocatalytic TiO2 with Controlled Hierarchical Structure

Three-dimensional (3D) hierarchical TiO2 structures were obtained by a facile solvothermal process. Various analytical techniques were used to characterize the crystal phase, morphology and optical absorption of the obtained samples. The experimental results indicate that the morphology could be tailored by adjusting the volume ratio of glycerol to ethanol. The investigation of photocatalytic performance shows that all the as-prepared TiO2 samples possess an excellent photocatalytic activity superior to commercial P25 in the degradation of Rhodamine B (RhB) dye under UV-light irradiation. In addition, the optimized volume ratio of ethanol to glycerol is 20 : 15. The possible mechanism related to the photocatalytic activity of the sample is discussed in detail. The enhanced photocatalytic activities of TiO2 samples could result from their hierarchical structures assembled by 1D nanorods and large light-harvesting efficiency.

Engineering of nanonetwork-structured carbon to enable high-performance potassium-ion storage

Potassium-ion batteries (KIBs) have been developed as an emerging electrochemical energy storage device due to the low cost and abundant resource of potassium. However, they suffer insufficient cyclability and poor rate capability caused by the large K+, severely limits their further applications. Herein, a nanonetwork-structured carbon (NNSC) is reported to address the issue. Cycling stability with very low decay rate of 0.004% per cycle over 2000 cycles and excellent rate capability (i.e., 261 mAh g−1 at 100 mA g−1 and 108 mAh g−1 at 5000 mA g−1) are achieved. The superior performance is attributed to the unique structure of NNSC, in which the three-dimensional interconnected hierarchical porous structure with hollow nanosphere as network units not only can effectively alleviate the volume expansion induced by the insertion of large K+, but also can offer fast pathways for K+ diffusion. In addition, the local graphitized carbon shell of NNSC can promote conductivity of material and reduce the resistance to K+ transportation. Thus, the NNSC has great potential in developing stable-structure and high-rate electrodes for next generation KIBs.

Micelle-template synthesis of a 3D porous FeNi alloy and nitrogen-codoped carbon material as a bifunctional oxygen electrocatalyst

The sluggish kinetics of oxygen reduction reaction and oxygen evolution reaction (ORR/OER) are the key scientific issues that need to be addressed for the application of renewable energy technologies. Rational coupling transition metal with porous heteroatom-doped carbon is extensively investigated as an efficient strategy to achieve high performance ORR/OER nonprecious metal electocatalysts. In this study, a FeNi alloy coated with N-doped carbon material (namely FeNi/NC) was designed by using triblock copolymer Pluronic F127 as a surfactant co-assembly with g-C3N4. This strategy enabled FeNi/NC possessing a high BET surface area in terms of three-dimensional hierarchical porous structure together with abundant defect sites. The optimized FeNi/NC catalyst displays an excellent oxygen electrode electrocatalytic activity with a potential gap △E of 0.77 V in alkaline media which substantially outperformed benchmark Pt/C + RuO2 (△E = 0.80 V). Furthermore, it shows almost no decay after long-time cycling tests for ORR/OER. The excellent catalytic performance along with the low cost for FeNi/NC catalyst makes it possible to commercialize the renewable energy devices.

Ion Exchange Synthesis of Cobalt Ion Modified Titanate Nanoarray as an Electrocatalyst toward Efficient Hydrogen Evolution Reaction

Cobalt ion modified titanate nanoarray (CTO NA) with a three-dimensional hierarchical structure is synthesized via a facile ion exchange strategy and further developed as an electrocatalyst toward ...

Hydrothermally Synthesized CuCo2S4 Nanosheets as an Easily Accessible and Convenient Heterogeneous Catalyst for the Sonogashira Cross-Coupling Reactions

A high surface area and the possibility of high charge separation and transportability make the two-dimensional (2D) nanomaterials very special in many applications, particularly in the field of catalysis. The usefulness of 2D nanomaterial is positively demonstrated in this study by employing it as an efficient heterogeneous catalyst in Sonogashira cross-coupling reaction, where the later one is well known for the formation of carbon–carbon bonds. 2D nanosheets of CuCo2S4 are synthesized using a hydrothermal synthesis and the average thickness of the sheets is found to be in the range of 10−15 nm. The transparent nanosheets are interconnected to form thick sheets and then aggregated to form a highly open three-dimensional hierarchical structure. This study explores the Sonogashira reaction very efficiently in water/ethanol at room temperature using hydrothermally synthesized CuCo2S4 nanosheets as catalyst for the C-C coupling reaction for the first time. The developed method is found to be economic, green, high yields, low catalyst loading and reusability of the catalysts. This present CuCo2S4 nanosheet heterogeneous catalyst afford the Sonogashira coupling of various aryl halides with terminal alkynes, giving a variety of aryl acetylenes in excellent yields and can be recovered by a simple filtration and reused for at least ten consecutive reactions with almost constant yield and activity.