1D Hierarchical Structures Research Articles

Highly stretchable and sensitive SBS/Gr/CNTs fibers with hierarchical structure for strain sensors

• Hierarchical fiber with CNTs and graphene was fabricated by solution etching. • The sensing performance of strain sensor was greatly improved by solution etching. • The sensor has a gauge factor up to 1667 over a wide strain range from 0 to 500%. • Its working range was 31 times larger than that of the non-etched fiber based sensor. Most of the reported flexible strain sensors can only normally sense external stretch in a quite narrow working range and with low sensitivity. In order to overcome these drawbacks, elastomeric fiber based strain sensors incorporating graphene (Gr) and carbon nanotubes (CNTs) were initially fabricated via coaxial wet spinning. The solution etching method was employed for forming a 1D@2D@1D hierarchical structure, with pores and microcracks on fibers, to reconstruct their conductive networks. The solution etched fiber based strain sensors achieved a significant improvement in obtaining a high maximum gauge factor of 1667 and capability of working over a wide strain range (0-500%, approximately 31 times larger than that for the non-etched fiber). Furthermore, the strain sensor showed excellent durability over 10000 tensile strain cycles. Finally, the based strain sensor was used to monitor physiological movements such as finger, elbow and knee bending with fast and accurate responses.

Integrating Multi‐Heterointerfaces in a 1D@2D@1D Hierarchical Structure via Autocatalytic Pyrolysis for Ultra‐Efficient Microwave Absorption Performance (Small 13/2022)

Microwave Absorption In article number 2105411, Xiaolong Jia and co-workers construct a 1D@2D@1D hierarchical structure integrated with multi-heterointerfaces to boost the microwave absorption efficiency of materials. This design has greatly reduced the threat of electromagnetic pollution caused by the explosive development of communication technology.

Integrating Multi-Heterointerfaces in a 1D@2D@1D Hierarchical Structure via Autocatalytic Pyrolysis for Ultra-Efficient Microwave Absorption Performance.

Developing microwave absorption (MA) materials with ultrahigh efficiency and facile preparation method remains a challenge. Herein, a superior 1D@2D@1D hierarchical structure integrated with multi-heterointerfaces via self-assembly and an autocatalytic pyrolysis is designed to fully unlock the microwave attenuation potential of materials, realizing ultra-efficient MA performance. By precisely regulating the morphology of the metal organic framework precursor toward improved impedance matching and intelligently integrating multi-heterointerfaces to boosted dielectric polarization, the specific return loss value of composites can be effectively tuned and optimized to -1002dB at a very thin thickness of 1.8mm. These encouraging achievements shed fresh insights into the precise design of ultra-efficient MA materials.

Hydrothermal synthesis of caterpillar-like one-dimensional NiCO3 nanosheet arrays and primary lithium battery application.

Transition metal carbonates have shown great potential as anode materials for next-generation lithium-ion batteries (LIBs), due to their super-high capacity. However, pure-phase NiCO3 with high electrochemical activity has not been reported to date. Herein, highly uniform caterpillar-like one-dimensional (1D) NiCO3 nanosheet arrays have been successfully synthesized using a facile hydrothermal route and have been evaluated as an anode material for LIBs. Profiting from the unique 1D hierarchical structure and spaces between the neighboring nanosheets, the as-prepared NiCO3 requires lower activation energy and delivers quick lithium-ion diffusion kinetics. These attributes result in a high capacity of 893 mA h g-1 after 150 cycles and excellent rate performance, superior to those of most reported transition metal carbonates. Cyclic voltammetry, ex situ X-ray diffraction and X-ray photoelectron spectroscopy reveal the lithium storage mechanism.

Multi-Path Electron Transfer in 1D Double-Shelled Sn@Mo2 C/C Tubes with Enhanced Dielectric Loss for Boosting Microwave Absorption Performance.

1D tubular micro-nano structural materials have been attracting extensive attention in the microwave absorption (MA) field for their anisotropy feature, outstanding impedance matching, and electromagnetic energy loss capability. Herein, unique double-shelled Sn@Mo2 C/C tubes with porous Sn inner layer and 2D Mo2 C/C outer layer are successfully designed and synthesized via a dual-template method. The composites possess favorable MA performance with an effective absorption bandwidth of 6.76GHz and a maximum reflection loss value of -52.1dB. Specifically, the rational and appropriate construction of Sn@Mo2 C/C tubes promotes the multi-path electron transfer in the composites to optimize the dielectric constant and consequently to enhance the capacity of electromagnetic wave energy dissipation. Three mechanisms dominate the MA process: i) the conductive loss resulted from the rapid electron transmission due to the novel 1D hollow coaxial multi-shelled structure, especially the metallic Sn inner layer; ii) the polarization loss caused by abundant heterogeneous interfaces of Sn-Mo2 C/C and Mo2 CC from the precise double-shelled structure; iii) the capacitor-like loss by the potential difference between Mo2 C/C nanosheets. This work hereby sheds light on the design of the 1D hierarchical structure and lays out a profound insight into the MA mechanism.

Nickel-doped Co4N nanowire bundles as efficient electrocatalysts for oxygen evolution reaction

Cost-efficient electrocatalysts composed of earth-abundant elements are highly desired for enhanced oxygen evolution reaction (OER). As a promising candidate, metallic Co4N already demonstrated electrocatalytic performance relying on specific nanostructures and electronic configurations. Herein, nickel was introduced as the dopant into one-dimensional (1D) hierarchical Co4N structures, achieving effective electronic regulation of Co4N toward high OER performance. The amount of Co3+ increased after Ni-doping, and the in-situ formed surface oxyhydroxide during OER enhanced the electrocatalytic kinetics. Meanwhile, the 1D hierarchical structure further promoted the performances of Co4N owing to the high electrical conductivity and abundant active-sites on the rough surface. As expected, the optimal Ni-doped Co4N with a Ni/Co molar ratio of 0.25 provides a small overpotential of 233 mV at a current density of 10 mAcm−2, with a low Tafel slope of 61 mV dec−1, and high long-term stability in 1.0 mol L−1 KOH. Following these results, the enhancement by doping the Co4N nanowire bundles with Fe and Cu was further evidenced for the OER.

In-situ fabrication of carbon-metal fabrics as freestanding electrodes for high-performance flexible energy storage devices

Hierarchical 1D carbon structures are attractive due to their mechanical, chemical and electrochemical properties however the synthesis of these materials can be costly and complicated. Here, through the combination of inexpensive acetylacetonate salts of Ni, Co and Fe with a solution of polyacrylonitrile (PAN), self-assembling carbon-metal fabrics (CMFs) containing unique 1D hierarchical structures can be created via easy and low-cost heat treatment without the need for costly catalyst deposition nor a dangerous hydrocarbon atmosphere. Microscopic and spectroscopic measurements show that the CMFs form through the decomposition and exsolution of metal nanoparticle domains which then catalyze the formation of carbon nanotubes through the decomposition by-products of the PAN. These weakly bound nanoparticles form structures similar to trichomes found in plants, with a combination of base-growth, tip-growth and peapod-like structures, where the metal domain exhibits a core(graphitic)-shell(disorder) carbon coating where the thickness is in-line with the metal-carbon binding energy. These CMFs were used as a cathode in a flexible zinc-air battery which exhibited superior performance to pure electrospun carbon fibers, with their metallic nanoparticle domains acting as bifunctional catalysts. This work therefore unlocks a potentially new category of composite metal-carbon fiber based structures for energy storage applications and beyond.

Polypyrrole Nanofibers with Extended 1D Hierarchical Structure

AbstractA two‐step electrochemical synthesis of polypyrrole nanofibers with a fractal‐like surface structure is described. The bilayer structure of polypyrrole on a Pt substrate provided protection of the polymer against overoxidation. The polypyrrole bilayer is electronically conductive. Specific charge‐transport properties originated from the primary counter ions used in the two‐step electrosynthesis. When the outer layer of polypyrrole was involved in cation exchange during redox switching, the inner layer of anion exchanging polypyrrole was set at its conductive oxidized state, thus providing a stable reversible redox activity of the former. The growth dimensionality of the outer layer (1D or 2D) depended on the concentration of the anionic surfactant in the polymerization solution.

Solution synthesis of conveyor-like MnSe nanostructured architectures with an unusual core/shell magnetic structure

We report for the first time one-dimensional (1D) wurtzite (WZ) MnSe nanoconveyors with a single-crystalline configuration fabricated by a solution-processed colloidal method. High-resolution transmission electron microscopy (HRTEM) measurements show that the stem of MnSe nanoconveyors grows along the [100] direction, while the teeth grow along the [0001] direction. We find that the initial WZ nanobelts with the [100] growth direction are crucial to the formation of nanoconveyors, whereas the teeth are a result of a self-catalyzed growth process induced by the Mn-terminated (0001) surface. The magnetic measurements suggest that 1D WZ MnSe nanoconveyors consist of an antiferromagnetic core and a ferromagnetic shell below the blocking temperature. Furthermore, the hysteresis measurements indicate that these nanoconveyors have 300 Oe coercive fields, which is attributed to the high surface-to-volume ratio of the nanoconveyors. This facile solution-based strategy can be anticipated to synthesize WZ metal chalcogenide nanomaterials with 1D hierarchical structures, for potential applications from spintronics to photocatalysis.

Bismuth Telluride quantum dot assisted Titanium Oxide microflowers for efficient photoelectrochemical performance

The 3D TiO2 microflowers sensitized by Bi2Te3 nanoparticles such novel nanostructure employed by two step synthesis strategy such as hydrothermal method and potentiostatic electrodeposition technique. Herein we have successfully synthesized Bi2Te3 nanoparticles loaded TiO2 photoanode for quantum dot-sensitized solar cells (QDSSCs). The combined 3D and 1D hierarchical structure has significant potential as an efficient photoanode for QDSSC.

Electrospinning technique synthesis and electrical performances of one dimensional Ca2Co2O5 with hierarchical structure

One dimensional (1D) Ca2Co2O5 with hierarchical structure has been fabricated by electrospinning successfully for the first time. The formation process of hierarchical structure Ca2Co2O5 are investigated by powder X-ray diffraction and scanning electron microscopy. High Seebeck coefficient (maximum value of 191μVK−1) and power factor (maximum value of 1.85×10−4Wm1K−2 at 963K) could be realized by fabricating 1D hierarchical structure assembled by nanoplates. This work provides a step forward in the design of other materials with similar layered building blocks in the crystal structure.

Formation of 1D Hierarchical Structures Composed of Ni3S2 Nanosheets on CNTs Backbone for Supercapacitors and Photocatalytic H2 Production

AbstractOne‐dimensional (1D) hierarchical structures composed of Ni3S2 nanosheets grown on carbon nanotube (CNT) backbone (denoted as CNT@Ni3S2) are fabricated by a rational multi‐step transformation route. The first step involves coating the CNT backbone with a layer of silica to form CNT@SiO2, which serves as the substrate for the growth of nickel silicate (NiSilicate) nanosheets in the second step to form CNT@SiO2@NiSilicate core‐double shell 1D structures. Finally the as‐formed CNT@SiO2@NiSilicate 1D structures are converted into CNT‐supported Ni3S2 nanosheets via hydrothermal treatment in the presence of Na2S. Simultaneously the intermediate silica layer is eliminated during the hydrothermal treatment, leading to the formation of CNT@Ni3S2 nanostructures. Because of the unique hybrid nano‐architecture, the as‐prepared 1D hierarchical structure is shown to exhibit excellent performance in both supercapacitors and photocatalytic H2 production.