Coral-like Nanostructures Research Articles

Bimetallic-Coordinated Covalent Triazine Framework-Derived FeNi Alloy Nanoparticle-Decorated Coral-Like Nanocarbons for Oxygen Electrocatalysis.

It is highly desirable to fabricate transition bimetallic alloy-embedded porous nanocarbons with a unique nanoarchitecture for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in rechargeable zinc-air batteries. In this work, we introduce a template-assisted in situ alloying synthesis of FeNi alloy nanoparticle-decorated coral-like nanocarbons (FeNi-CNCs) as efficient OER/ORR dual-functional electrocatalysts. The present materials are produced through polycondensation of a covalent triazine framework (CTF), the coordination of Ni and Fe ions, and sequential pyrolytic treatment. Through the pyrolysis process, the nanolamellar FeNi-CTF precursors can be facilely converted into FeNi alloy nanoparticle-decorated nanocarbons. These nanocarbons possess a distinctive three-dimensional (3D) coral-like nanostructure, which is favorable for the transport of oxygen and the diffusion of electrolyte. As a result, FeNi-CNC-800 with the highest efficiency exhibited remarkable electrocatalytic performance and great durability. Additionally, it also can be assembled into rechargeable zinc-air batteries that can be assembled in both liquid and solid forms, offering a superior peak power density, large specific capacity, and outstanding reusability during charging/discharging cycles (e.g., 5160 charging-and-discharging cycles at 10 mA cm-2 for the liquid forms). These traits make it a highly promising option in the burgeoning field of wearable energy conversion.

Assembling molybdenum-doped platinum clusters into a coral-like nanostructure for highly enhanced oxygen reduction

Regulating the electronic and geometric structures of electrocatalysts is an effective strategy to boost their catalytic properties. Herein, a coral-like nanostructure is assembled with Mo-doped Pt clusters to form a highly active catalyst toward the oxygen reduction reaction (ORR). The advantages of a Mo-doped porous skeleton, grain boundaries, and MoOx species on the Pt cluster surfaces synergistically boost the electrocatalytic performance. This unique architecture delivers 3.5- and 2.8-fold higher mass and specific activities, respectively, than commercial Pt/C. Density functional theory calculations reveal that the Mo-doped Pt clusters have an optimized Pt–O bond length of 2.110 ​Å, which weakens the adsorption energy of the intermediate O∗ to yield great ORR activity. Moreover, the catalyst shows a decay in the half-wave potential of only 8 ​mV after 10,000 cycles of accelerated durability testing. The high stability arises from the increased dissociation energy of Pt atoms and the stable architecture of the coral-like structure of clusters.

Alkaline Media Regulated NiFe-LDH-Based Nickel–Iron Phosphides toward Robust Overall Water Splitting

The search for low-cost, high-performance, and robust stability bifunctional electrocatalysts to substitute noble metals-based counterparts for overall water splitting to generate clean and sustainable hydrogen energy is of great significance and challenges. Herein, a high-efficient bi-functional nickel–iron phosphide on NiFe alloy foam (denoted as e-NFP/NFF) with 3D coral-like nanostructure was controllably constructed by means of alkali etching and the introduction of non-metallic atoms P. The unique superhydrophilic coral-like structure can not only effectively facilitate the exposure of catalytic active sites and increase the electroactive surface area, but also accelerate charge transport and bubble release. Furthermore, owing to the synergistic effect between the bicomponent of nickel–iron phosphides as well as the strong electronic interactions of the multiple metal sites, the as-fabricated catalyst behaves with excellent bifunctional performance for the hydrogen evolution reaction (overpotentials of 132 and 286 mV at 10 and 300 mA·cm−2, respectively) and oxygen evolution reaction (overpotentials of 181 and 303 mV at 10 and 300 mA·cm−2, respectively) in alkaline electrolytes. Impressively, cells with integrated e-NFP/NFF electrodes as a cathode and anode require only a low cell voltage (1.58 V) to drive a current density of 10 mA·cm−2 for overall water splitting, along with remarkable stability in long-term electrochemical durability tests. This study provides a tunable synthetic strategy for the development of efficient and durable non-noble metal bifunctional catalysts based on the construction of an elaborate structure framework and rational design of the electronic structure.

One-pot electrochemical synthesis of ultrathin trimetallic Mn-Sn-Co oxide coral-like nanostructure as free-standing active electrode material for energy storage applications

The present study proposes a facile and controllable approach for the design and fabrication of an ultrathin binder-free trimetallic oxide nanostructure on nickel foam as an efficient hybrid supercapacitor. The morphological and physicochemical characteristics of the as-prepared Mn-Sn-Co-1 oxide (MSCO-1) electrode were validated using various techniques. The integrated MSCO-1 electrode displayed a high area-specific capacitance of 4.15 F cm−2 at 1 A g−1, good rate capability, and excellent cycling stability of 92.9 % capacitance retention after 3000 CD cycles in a three-electrode system. Its superior electrochemical performance is related to the distinctive coral-like morphology with a hierarchical porous network structure and synergistic effects of the multi-component metal oxides, effectively improving the electroactive sites and assisting the ease penetration of both electrolyte ions and electrons. Likewise, the corresponding asymmetric supercapacitor (ASC) was successfully fabricated by assembling MSCO-1 and activated carbon (AC) as cathode and anode, respectively, exhibiting a high energy density of 39.6 Wh kg−1 at 800 W kg−1 along with superior cycling stability. Moreover, the asymmetric supercapacitor suggests a good state of health with a small leakage current and low self-discharge, which can maintain 1.2 V of its initial voltage (1.6 V) after eight hours of self-discharge test. We also demonstrated the illumination of a yellow LED indicator for more than 480 s. These exciting results render that the MSCO-1 nanostructure could be a promising electrode in developing energy storage systems for feasible applications.

Design a SnWO4 coral-like nanostructure for triethylamine (TEA) sensing

The gas sensors of semiconducting metal oxide are commonly deemed to be a promising sensor type. This work introduces a synthesizing method for SnWO4 sensor with coral-like by simple hydrothermal strategy. The acquired SnWO4 products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Tests revealed scheelite SnWO4 sample was successfully prepared and the vacancy oxygen and lattice oxygen respectively accounted for 74.35% and 25.65% in the oxygen element distribution. The gas sensing performances of SnWO4 coral-like were investigated via static gas sensor testing system. What's more, the response of SnWO4 sensor to 200 ppm triethylamine (TEA) is 17.58 at the optimum operating temperature (240 °C). And it expresses unique selectivity and long-term stability to triethylamine (TEA). This paper proves for the first time that SnWO4 nanomaterial can be used as a noval material in gas sensor field.

Investigation into anti-dust wetting surface with coral-like nanostructures reinforced by electrospun composite nanofibers

Investigation into anti-dust wetting surface with coral-like nanostructures reinforced by electrospun composite nanofibers

Photo-Induced Synthesis of Coral-Like Hierarchical Ag–Fe Bimetallic Multifunctional Nanostructures

Herein, we report, for the first time, rapid and facile photo-induced synthesis of hierarchical Ag–Fe bimetallic nanostructures with tailorable morphologies based on variation of Fe2+ concentrations at the submillimolar level. The synthesis methodology relies on the photo-oscillation of the Fe(II)–Fe(III)–Fe(II) system in the aqueous medium, leading to reduction of Ag+ to Ag0 nanoparticles ,wherein Ag0 nanoparticles are stabilized in an Fe-oxide framework. The morphology of the product is tailored from scattered to prominent coral-like nanostructures by simply varying the Fe2+ concentrations at the submillimolar level. The developed method eliminates the essential need of presynthesized precursor metal nanoparticles, toxic templates or surfactants, organic solvents, and sophisticated instrumentations or stringent reaction conditions. Coral-like FeFe2O4 nanostructures with hairy extensions ensured high surface area wherein monodispersed nano-Ag0 (2.31 ± 1.01 nm) are homogeneously distributed and stabilized without any capping agent. The excellent As3+ removal efficiency (99.9%) of the synthesized material, even from a low but realistic contamination concentration (100 ppb) and high Kd value (4.9 × 106 mL/g), is ascribed to the synergistic effect due to reactivity of Ag and Fe toward arsenite. A single treatment with the material (0.15 g/L) efficiently lowers As(III) concentration to well below the U.S. Environmental Protection Agency drinking water limits (10 ppb). Ag–Fe bimetallic also exhibits excellent synergistic antibacterial efficacy against both Gram (+/−) bacteria. Thus, the findings open-up the possibility of expanding the applications of hierarchical Ag–Fe bimetallic nanostructures in water treatment.

Mechanically and chemically robust molybdenum carbide-graphene hybrid conductors

Although transition metal carbides (TMCs) exhibit intriguing physical and chemical properties, a central issue for multifaceted applications based on TMC materials is to meet a large-scale and reliable synthetic route of air-stable TMC materials. Here, the primary aim is to address the issues by synthesizing Mo2C encapsulated with multilayer graphene coral-like nanostructure. The oxidation stability of Mo2C can be effectively compensated by the complementary hybridization of multilayer graphene, which serves as a perfect chemical barrier. Large-scale graphene/Mo2C can be readily synthesized on commercial Mo foils by surface-oxidation-mediated chemical vapor deposition. Explicit structural and chemical evaluation was implemented to explore the structural and chemical manipulation of Mo2C by selecting the starting material (Mo or MoO3). Differences in the thickness of the oxide layers on the Mo surface led to structural and material diversities for the formation of Mo2C with nanogranular and graphene/Mo2C coral-like nanostructures. The capability of graphene/Mo2C for applications in nanostructured electrodes and heaters was validated by its extraordinary electrical conductivity, substantial enhancement in chemical durability and mechanical flexibility, and outstanding performance of deformable heaters.

Facile fabrication of a three-dimensional coral-like silicon nanostructure coated with a C/rGO double layer by using the magnesiothermic reduction of silica nanotubes for high-performance lithium-ion battery anodes

Silicon has an ultrahigh theoretical capacity and has been regarded as the best choice for next-generation lithium-ion battery anodes, but it also suffers from dramatic expansion during cycling. Herein, a novel three-dimensional coral-like Si nanostructure coated with C/rGO (CL-Si@C/rGO) was facilely prepared through the high-temperature magnesiothermic reduction of SiO2 nanotubes, which were then coated with C/rGO. Systematic tests verified the unique coral-like nanostructure, which was formed by the magnesiothermic reduction of several SiO2 nanotubes at high temperature. The internal voids and outer C/rGO layer of CL-Si@C/rGO could effectively manage the volume expansion phenomenon while enhancing the electrical conductivity of the electrode, respectively. Benefiting from the ability to maintain the electrode integrity and the outer C/rGO layer of this unique nanostructure, the CL-Si@C/rGO composite electrode could maintain a reversible specific discharge capacity of 739.1 mAh g−1, even at a high current density of 2 A g−1. Furthermore, this composite electrode exhibited a 0.5% capacity loss from the 3rd to the 100th cycle at a current density of 1 A g−1. This work provides a simple, economic, and environmentally friendly procedure for the industrial production of high-performance Si-based anodes.

Correction to Chemical Self-Assembly of Multifunctional Hydroxyapatite with Coral-like Nanostructure for Osteoporotic Bone Reconstruction.

Correction to Chemical Self-Assembly of Multifunctional Hydroxyapatite with Coral-like Nanostructure for Osteoporotic Bone Reconstruction.

Preparation of Coral-like SnO2 Hierarchical Nanostructures and Its Application in Ethanol Gas-sensing Performance

Coral-like SnO2 hierarchical nanostructures were successfully fabricated by a simple hydrothermal route. By means of a comprehensive analysis of microstructures and morphologies of the hierarchical SnO2, we found that the coral-like nanostructures were comprised of irregular nanorods and nanosheets. Considering the essential advantages of hierarchical architectures, its gas sensitivity and the formation mechanism have been further explored. The sensor response to 100 ppm ethanol is about 25 at the optimum working temperature of 240 °C, and the response and recovery time are about 17 s and 7 s, respectively. Based on the experimental results, a possible morphology-dependent sensing mechanism are speculated.

Irradiation effects of H/He neutral beam on different forged tungsten materials

Tungsten has been considered as the most promising plasma-facing materials (PFMs) for the future fusion reactor due to its excellent chemical and physical properties. In this work, different kinds of tungsten-based PFMs including pure W, W-K, and W-Y2O3 alloys were prepared via powder metallurgy. Then, high-energy rate forging was used for the plastic deformation to refine the grain size of the samples and increase their densities. To evaluate the service performance of these tungsten-based PFMs under edge plasma conditions, the deformed samples were exposed to high-energy hydrogen (H) neutral beam doped with 6 at% helium (He). Sequentially, edge-localized mode-like transient loadings (1 ms, 100 cycles) were carried out on the specimens with neutral beam pre-loading to study the impact of H/He pre-loading on the generation and propagation of cracks. The microstructural changes of the exposed surfaces were observed by scanning electron microscopy with the help of focused ion beam. The experimental results indicate that H/He neutral beam irradiation could induce obvious surface damages of the tested samples. For example, pinhole and coral-like nanostructures were formed on the surfaces of the exposed samples, as the surface temperatures were relatively high. The cracking thresholds of the W-Y2O3 samples with and without neutral beam pre-irradiations were both between 0.22 and 0.33 GW m−2, while the cracking thresholds of pure W and W-K samples were less than 0.22 GW m−2. This result indicates that the H/He neutral beam pre-loading has no significant impact on the cracking threshold. In addition, the crack pattern on the surface of the exposed samples closely depends on the grain boundary pattern.

Efficient Photocatalytic Fuel Cell via Simultaneous Visible-Photoelectrocatalytic Degradation and Electricity Generation on a Porous Coral-like WO3/W Photoelectrode.

Photocatalytic fuel cells (PFCs) have proven to be effective for generating electricity and degrading pollutants with a goal to resolve environmental and energy problems. However, the degradation of persistent organic pollutants (POPs), such as perfluorooctanoic acid (PFOA), remains challenging. In the present work, a porous coral-like WO3/W (PCW) photoelectrode with a well-designed energy band structure was used for the photoelectrocatalytic degradation of POPs and the simultaneous generation of electricity. The as-constructed bionic porous coral-like nanostructure greatly improved the light-harvesting capacity of the PCW photoelectrode. A maximum photocurrent density (0.31 mA/cm2) under visible light (λ > 420 nm) irradiation and a high incident photon conversion efficiency (IPCE) value (5.72% at 420 nm) were achieved. Because of the unique porous coral-like structure, the suitable energy band position, and the strong oxidation ability, this PCW photoelectrode-based PFC system exhibited a strong ability for simultaneous photoelectrocatalytic degradation of PFOA and electricity generation under visible-light irradiation, with a power output of 0.0013 mV/cm2 using PFOA as the fuel. This work provides a promising way to construct a reliable PFC using highly toxic POPs to generate electricity.

Fabrication of 3D hierarchically structured carbon electrode for supercapacitors by carbonization of polyaniline/carbon nanotube/graphene composites

Composite materials with carbon nanotubes (CNTs) and graphene oxide (GO) are considered to be superior for energy storage applications due to their intriguing structural and electrical properties. The electrochemical performance of CNT/GO-based electrodes can be improved by introducing porous carbon materials into them. Herein, we have carbonized the composite consisted of polyaniline (PANI), GO and CNTs on stainless steel plates and investigated their electrochemical performances as a free-standing and binder-free electrode for supercapacitors. The carbonized PANI with a coral-like nanostructure was formed over CNT and GO surface. Furthermore, the introduction of GO efficiently prevents the excessive agglomeration of PANI in the resultant composite materials. The carbonized composite electrode exhibited the high specific capacitance of 465 mF cm−2 at a current density of 1 mA cm−2. Moreover, the carbon electrode obtained by annealing at a higher temperature of 550 °C showed the excellent rate capability and cyclic stability. For example, the 78% of initial capacitance retention was observed when the current density changed from 1 mA cm−2 to 8 mA cm−2, and the capacitance retention of 84% was achieved after 1000 charge/ discharge cycles. This 3D hierarchically structured carbon electrode can be considered as a potential candidate for next-generation energy storage devices.

A tandem photoelectrochemical water splitting cell consisting of CuBi2O4 and BiVO4 synthesized from a single Bi4O5I2 nanosheet template.

We report on a simple and facile synthetic approach for preparing both a CuBi2O4 photocathode and BiVO4 photoanode from a single Bi4O5I2 nanosheet template. A nanosheet structured Bi4O5I2 (nanoBi4O5I2) template, solvothermally deposited on a conducting glass substrate, can be converted to a textured CuBi2O4 photocathode and a BiVO4 photoanode with coral-like nanostructure by drop-casting a copper ion-containing and a vanadium ion-containing solution, respectively, with a follow-up heat treatment. UV-vis absorption spectra and Mott-Schottky analyses confirm CuBi2O4 and BiVO4 have well-suited band gaps for absorbing a large portion of visible light and complementary band structures for proton reduction and water oxidation, respectively. A photoelectrochemical tandem cell, consisting of a cobalt based catalyst modified CuBi2O4 photocathode and a cobalt based catalyst modified BiVO4 photoanode shows promising photoelectrochemical properties towards water splitting, and can be operated without an external bias. Factors limiting the performance of the tandem cell are also discussed.

Synthesis of 3D-coral like polyaniline nanostructures using reactive oxide templates and their high performance for ultrasensitive detection of blood cancer

We report the synthesis of 3D coral like polyaniline nanostructures (PANI-NC), using in situ sacrificial oxidative template route. The coral-like nanostructures were developed as electrode materials for biosensing applications by depositing it electrophoretically onto indium tin oxide (ITO) coated glass substrates. These fabricated electrodes were characterized using various microscopic, and spectroscopic techniques which confirms the deposition of 3D PANI-NC on ITO electrode (PANI-NC/ITO). Electrochemical studies of the PANI-NC/ITO showed improved electron transfer behavior with a diffusion coefficient of 3.097 × 10−8 cm2/s and heterogeneous electron-transfer rate constant of 4.52 × 10−4 cm/s. Further, these electrodes were utilized for the immobilization of biotinylated DNA sequence (22 base pairs), identified from BCR–ABL fusion gene using avidin-biotin coupling. The electrochemical impedance spectroscopy analysis showed that the nucleic acid sensor exhibits a linear dynamic range from 10-6 M to 10-17 M of target DNA with a low detection limit (7 × 10−18 M). The high differentiation ability and specificity of the nucleic acid biosensor with various target DNA sequences (complementary, noncomplementary, one base mismatch and two base mismatch) and clinical samples of CML positive patients demonstrate its potential for clinical diagnostics.

Preparation and photocatalytic activity of CuO/ZnO composite nanostructured films

CuO/ZnO composite nanostructured films have been prepared by a simple two-step low-temperature hydrothermal approach. The morphology and structure characterizations demonstrated that CuO coral-like nanostructures were deposited on ZnO nanorod arrays. Experiment on the degradation of methylene blue under Xe lamp irradiation was carried out to evaluate the photocatalytic activities of the samples. It was found that the CuO/ZnO composite nanostructured films exhibited enhanced photocatalytic performances compared with the pure ZnO. This improvement can be ascribed to the enhanced visible light absorption and effective separation of photoexcited electrons and holes.

Chemical Self-Assembly of Multifunctional Hydroxyapatite with a Coral-like Nanostructure for Osteoporotic Bone Reconstruction.

Bone defects/fractures are common in older people suffering from osteoporosis. Traditional hydroxyapatite (HA) materials for osteoporotic bone repair face many challenges, including limited bone formation and aseptic loosening of orthopedic implants. In this study, a new multifunctional HA is synthesized by spontaneous assembly of alendronate (AL) and Fe3O4 onto HA nanocrystals for osteoporotic bone regeneration. The chemical coordination of AL and Fe3O4 with HA does not induce lattice deformation, resulting in a functionalized HA (Func-HA) with proper magnetic property and controlled release manner. The Func-HA nanocrystals have been encapsulated in polymer substrates to further investigate their osteogenic capability. In vitro and in vivo evaluations reveal that both AL and Fe3O4, especially the combination of two functional groups on HA, can inhibit osteoclastic activity and promote osteoblast proliferation and differentiation, as well as enhance implant osseointegration and accelerate bone remodeling under osteoporotic condition. The as-developed Func-HA with coordinating antiresorptive ability, magnetic property, and osteoconductivity might be a desirable biomaterial for osteoporotic bone defect/fracture treatment.

Controlled hydrothermal synthesis of graphene supported NiCo2O4 coral-like nanostructures: An efficient electrocatalyst for overall water splitting

With decreasing fossil fuels and rising environmental issues, harvesting energy in a large amount and in a clean way has been a great challenge for the whole world. Developing the efficient electrocatalysts with less expense and achieving the better electrocatalytic behavior for oxygen evolution reaction (OER), oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER) is very essential for extensive commercialization of fuel cells, water electrolyzers and metal air batteries. In the same pursuit, herein, we report a bifunctional coral-like NiCo2O4 nanostructure supported on reduced graphene oxide (rGO) sheets, which was prepared by a facile, controlled hydrothermal reaction protocol. The structural, morphological and electrochemical characterizations have been carried out to explore the properties of this nanocomposite. The unique morphology, large electroactive surface area and the synergistic effect of the metal ions on the electrocatalytic activity makes this material a suitable candidate for electrochemical water splitting. The low onset potential, high current density, lower Tafel slope and long-term stability in both HER and OER has been shown by rGO-NiCo2O4 coral like nanostructure, which reveals the high catalytic activity of this material, underlying the finding and importance of current work.

Facile fabrication of polyaniline with coral-like nanostructure as electrode material for supercapacitors

Polyaniline (PANI) with coral-like nanostructure was prepared via chemical oxidative polymerization in the presence of sunset yellow (SY) as dopant and surfactant. The results showed that in comparison with the microsized bulky structure of PANI undoped with SY, the coral-like nanostructure of PANI doped with SY (PANI/SY) was observed and the diameter of coral branch decreased from 180nm to 100nm with the increase of feeding molar ratio of SY to aniline. Coral-like PANI/SY showed the large specific capacitance of 467F/g and nice electrochemical stability when the feeding molar ratio of SY to aniline was 0.035:1, owning to its special coral-like nanostructure and high conductivity of 15.0S/cm, which was essentially attributed to the synergistic effects of high doping level, ordered arrangement of PANI chain and strong π–π interaction between PANI and SY.