3D Flower-like Nanostructures Research Articles

Smart nanozymes coupled with dynamic magnet field and laser exposures for cancer therapy

Developing nanozymes for cancer therapy has attracted great attention from researchers. However, enzymes-loaded magnetic particles triggered by both a low-frequency vibrating magnetic field (VMF) and laser for inhibiting tumor growth have never been reported. Herein, we developed a magnetic nanozyme with 3D flower-like nanostructures for cancer therapy. Specifically, the flower-like nanozymes exposed to a VMF could efficiently damage the mitochondrial membrane and cell structure, and inhibit tumor growth through magneto-mechanical force. In parallel, magnetic nanozymes in a weak acid environment containing glucose could generate abundant hydrogen peroxide through glucose oxidase-catalyzed oxidation of glucose, and further significantly promote the Fenton reaction. Interestingly, both glucose oxidase- and Fenton-based catalytic reactions were significantly promoted by the VMF exposure. Flower-like magnetic nanospheres upon a near-infrared laser irradiation could also damage cancer cells and tumor tissues through photothermal effect. The cell-killing efficiency of magnetic nanozymes triggered by the VMF or laser significantly increased in comparison with that of nanozymes without exposures. Mouse tumors grown after injection with magnetic nanozymes was inhibited in a significant way or the tumors disappeared after exposure to a VMF and laser due to the synergistic effect of four major stimuli, viz., magneto-mechanical force, photothermal conversion, improved Fenton reaction, and intratumoral glucose consumption-based starvation effect. This is a great platform that may be suitable for treating many solid tumors.

Engineering of Micro-mesoporous two-dimensional CeO2-based heterojunction oxides for energy storage applications

With growing demands on energy supply and storage, there is a need for advanced devices that can meet the high power and energy requirements. One such device is a supercapacitor, which is classified into two types, namely the electrical double-layer capacitor (EDLC) and the pseudocapacitor. Pseudocapacitors show energy storage properties that are between EDLCs and batteries and generally, transition metal oxides are used for these applications. Recent work has demonstrated that CeO2 is a potential material for such applications owing to its reversible charge-switching capabilities and good stability in different environments. In the present work, novel ultrathin nanosheets of CeO2-x and a composite of ruthenium (Ru)-CeO2-x, with the Ru in the form of mixed heteroatoms and dopants were synthesised using a Ce-based coordination polymer (Ce-CP) as the precursor using modified anodic chronoamperometric electrodeposition (MACE) technique. The ready exfoliation of Ce-CP in triethanolamine, which was the exfoliation medium, followed by solvent removal and annealing at 300 °C resulted in the formation of ultrathin 2D CeO2 nanosheets that are partially stacked, resulting in the formation of flower-like 3D nanostructures. The ultrathin 2D CeO2 formed 3D flower-like nanostructures with high concentrations of defects, active sites, and mesopores, which increased with the concentration of Ru in the CeO2-x nanostructure. Additionally, the specific surface area of the Ru-CeO2-x samples was higher, increasing to 354 m2·g−1 compared to the value of 146 m2·g−1 for pristine CeO2-x. The cyclic voltammetry analysis revealed that the introduction of Ru increased the capacitance of pristine CeO2-x from 665 F·g−1 to 923 F·g−1 at a scan rate of 5 mV·s−1. These findings suggest that Ru-CeO2-x nanosheets have potential for use in supercapacitor applications.

Three-dimensional core–shell CoFe Prussian blue analog at NiCoFe layered ternary hydroxide electrocatalyst for efficient oxygen evolution reaction

Layered double hydroxides are one of the most effective electrocatalysts owing to their compositional and structural flexibility. However, their self-stacking leads to limited active sites and low conductivity. In this work, a three-dimensional (3D) core–shell architecture with spatially separated active sites has been fabricated based on layered ternary nickel cobalt iron hydroxide (NiCoFe-LTH) nanosheets and cobalt iron Prussian blue analog (CoFe-PBA) on nickel foam (NF) (i.e., CoFe-PBA@NiCoFe-LTH/NF) with CoFe-PBA as self-sacrificial templates that are partially in situ transformed into NiCoFe-LTH nanosheets. The CoFe-PBA@NiCoFe-LTH/NF has a well-defined core–shell 3D flower-like nanostructure in which NiCoFe-LTH nanosheets create the larger shell while CoFe-PBA nanocubes form the small core. This hybrid structure is evaluated as an electrocatalyst for oxygen evolution reaction (OER) and found to exhibit a low overpotential of 228 mV at 10 mA cm−2, a low Tafel slope of 36 mV dec−1, and good catalytic stability for 72 h in 1.0 M alkaline solution. The strong performance is attributed to the unique 3D core–shell flower-like nanosheet architecture that avoids the stacking of the 2D LTH, provides abundant spatially separated active sites, and enhances electron transport and stability. Furthermore, the OER mechanism and growth process of the electrocatalysts were systematically studied. These results suggest that such electrocatalysts with unique architecture are promising for efficient and durable OER.

Nanostructural Co–MoS2/NiCoS supported on reduced Graphene oxide as a high activity electrocatalyst for hydrogen evolution in alkaline media

There are many tremendous challenges to enhance the hydrogen evolution reaction (HER) activity of MoS2. In this study, nanoflower-like Co–MoS2/NiCoS structure supported on reduced Graphene Oxide (rGO) was rationally developed via a simple hydrothermal route, where the synergistic regulations of both interface structural and electronic conductivity were successfully presented by using controllable interface engineering and Co metal ions doped into MoS2 nanosheets. Ascribed to the 3D flower-like nanostructure with massive active sites, the interface coupling effect between MoS2 and Ni–Co–S phase, and Co-doped MoS2 can modulate its surface electronic density. The optimal Co–MoS2/NiCoS/rGO hybrid exhibits excellent HER activity in 1.0 M KOH, with a small overpotential (η10, 84 mV) at 10 mA cm−2 and a low Tafel slope (46 mV dec−1), accompanied by good stability. This work provides an effective route to produce other electrocatalysts based on interface structure and electronic conductivity engineering for HER in the future.

The Adsorptive Ability of 3D Flower-Like Titanium Phosphate for U(VI) in Aqueous Solution

In the present work, 3D flower-like nanostructure titanium phosphates (F-TiP/T; T is the temperature of preparation in Celsius) were prepared through the reaction of tetrabutyl titanate (TBOT) with concentrated phosphoric acid. And F-TiP/T were applied to remove of U(VI). Furthermore, the effects of the preparation temperature, initial solution pH, and the kinetics and thermodynamics of U(VI) adsorbed by F-TiP/T were comprehensively explored. The characterization results of SEM and XRD indicated that the morphology of F-TiP/T was flower-like with a phase of Ti(HPO4)2•2H2O. Moreover, the adsorption results indicated that the processes were fitting to pseudo-first-order and Sips models and the saturated adsorption capacity was recorded as 295.13 mg·g−1. The extraction of U(VI) on F-TiP/T was dominated by ion exchange. The results above indicate that F-TiP/T is a potentially efficient U(VI) adsorbent, which could be utilized in the removal and immobilization of U(VI) in wastewater.

General synthesis of Pd-pm (pm = Ga, In, Sn, Pb, Bi) alloy nanosheet assemblies for advanced electrocatalysis.

Owing to the synergistic compositional and structural advantages, ultrathin bimetallic nanosheet assembly nanostructures are widely recognized as advanced catalysts for alcohol electrooxidation reaction. Although numerous efforts have been made, the fabrication of well-defined ultrathin bimetallic nanosheet assemblies (NSAs) at large scale is still a tough challenge. Herein, a universal synthetic approach has been proposed to produce a series of well-defined Pd-pm (pm = Ga, In, Sn, Pb, Bi) alloy NSAs. Due to multiple merits of their unique 3D flower-like nanostructure and alloyed crystalline features, the self-supported Pd-pm NSAs show excellent electrocatalytic performance for the methanol oxidation reaction (MOR) and glycerol oxidation reaction (GOR). Given the eco-friendly synthetic concept, facile universality, and outstanding electrocatalytic properties of the generated bimetallic Pd-pm NSAs, we believe that this method could be employed for building more advanced nanocatalysts toward efficient electrocatalytic applications.

Biomass carbon modified flower-like Bi2WO6 hierarchical architecture with improved photocatalytic performance

Novel Biomass carbon modified Bi2WO6 with 3D flower-like nanostructures were firstly fabricated through a hybridization approach, and investigated by multiple techniques including XRD, XPS, SEM and TEM analysis, etc. Compared with the pristine Bi2WO6, Bi2WO6/C hybrids exhibit higher visible-light photocatalytic activity and stability for tetracycline (TC) photodegradation. Moreover, the obviously enhanced photodegradation performance of Bi2WO6/C hybrids was mainly attributed to the modification of biomass carbon with good natures in specific surface area, narrow band gap (2.51 eV) and electronic transmission, which greatly improved the adsorption capacity and facilitated the separation of charge carriers. Furthermore, a possible photocatalytic mechanism of Bi2WO6/C hybrids in the view of active radicals has been discussed, which was also ascribed to the outstanding degraded ability of the ·OH evolved from the supersaturated ·O2− through trapping and ESR experiments. More importantly, these findings provide new insights to the utilization of biomass carbon modified other Bi-based photocatalysts and enhancing the photocatalytic performance to address environmental problems.

3D flower-like heterostructured TiO2@Ni(OH)2 microspheres for solar photocatalytic hydrogen production

TiO2@Ni(OH)2 core-shell microspheres were synthesized by a facile strategy to obtain a perfect 3D flower-like nanostructure with well-arranged Ni(OH)2 nanoflakes on the surfaces of TiO2 microspheres; this arrangement led to a six-fold enhancement in photocatalytic hydrogen evolution. The unique p-n type heterostructure not only promotes the separation and transfer of photogenerated charge carriers significantly, but also offers more active sites for photocatalytic hydrogen production. A photocatalytic mechanism is proposed based on the results of electrochemical measurements and X-ray photoelectron spectroscopy.

Fabricating visible-light photoactive 3D flower-like BiOCl nanostructures via a one-step solution chemistry method at room temperature

Three dimensional (3D) flower-like BiOCl nanostructures were synthesized by a facile and mild solution chemistry method at room temperature without any post-treatment. It is found that the volume ratios of ethylene glycol to water (EG-W) play an important role in the nucleation and growth of BiOCl, which consequently determine the self-assembly and thus the morphology of BiOCl nanostructures. In the solution of high EG-W ratio, the thin nanosheets self-assemble into 3D flower-like nanostructures, resulting in large surface area and abundant oxygen vacancies. The oxygen vacancies facilitate the trapping and transfer of photogenerated electrons to adsorbed oxygen molecules, producing active O2·− species. As a result, the BiOCl nanoflowers exhibit much higher photocatalytic activity for RhB degradation under visible light irradiation than their nanosheets counterparts synthesized in the solution of low EG-W ratios.

Fe-based multi-phase nanocrystalline ribbons with hierarchically flowerlike structured metal oxides after modified by Orange II for CrVI absorption

Three-dimensional flowerlike nanostructured metal oxides attached on the surfaces of Fe-based multi-phase nanocrystalline ribbons (Fe-MNRs) were prepared by a simple way (through immersing the Fe-MNRs in Orange II solution). It has been found that the as-prepared Fe-MNRs with 3D flowerlike nanostructures (Fe-MNRs + FNs) exhibit good absorption property for a typical heavy metal ion (CrVI) in wastewater, while Fe-MNRs do not possess such properties. The Fe-MNRs + FNs could remove 99% CrVI ions from the solution in 40 min, and this adsorption property can be attributed to the ion exchange between CrVI and surface hydroxyl groups (O–H) of 3D flowerlike nanostructures. The present result suggests that the Fe-MNRs + FNs, prepared by facile way, possess great potentials in removing heavy metallic ions in wastewater.

Nitrogen-doped 3D flower-like carbon materials derived from polyimide as high-performance anode materials for lithium-ion batteries

Nitrogen-doped 3D flower-like carbon materials (NFCs) have been fabricated using a simple and effective strategy, namely, the hierarchical assembly of polyimide (PI) and subsequent thermal treatment. The effect of pyrolysis temperature on the structural evolution process of PI is also investigated systematically. When evaluated as anode materials for lithium ion batteries (LIBs), the as-obtained NFCs, especially NFCs-550, exhibit good electrochemical performance, including a high reversible capacity (1488.1mAhg−1 at 0.05Ag−1), excellent rate performance (287.6mAhg−1 at 2Ag−1), and good cycling stability (645mAhg−1 with 96% retention after 300 cycles at 0.1Ag−1). The good electrochemical performance is attributed to the synergistic effect between 3D flower-like nanostructure and high nitrogen content. This approach may provide some inspiration to construct a series of heteroatom doped and hierarchical structured carbon materials using polymers for LIBs.

CZTS synthesis in aqueous media by microwave irradiation

Copper zinc tin sulfide (Cu2ZnSnS4, CZTS), a p-type semiconductor composed of non-toxic earth abundant elements, is a promising material for absorber layer application in thin film solar photovoltaics. The present work describes a relatively faster and reliable microwave irradiation technique to prepare CZTS powder in aqueous media. The CZTS phase of the as-synthesized powder was confirmed by X-ray diffraction and Raman spectroscopy. Optical properties i.e. band gap determined from Tauc plot of the optical absorption spectrum measured by UV–Vis spectroscopy was 1.27 eV, which is suitable for absorbing the solar radiation. The particle morphology studied under SEM and TEM analysis was found to be a 3D flower-like nanostructure formed from 2D layers of CZTS crystals. Further, the most probable mechanism for the formation of CZTS phase is explained.

Rapid room-temperature synthesis and visible-light photocatalytic properties of BiOI nanoflowers

Uniform hierarchical BiOI nanoflowers composed of nanoplates with rough surfaces have been synthesized by a mild and rapid room-temperature solution synthesis approach. The effects of reaction parameters on the formation of 3D flower-like nanostructure were discussed. The morphology variations of the nanostructures were achieved by simply varying the reaction parameters in the system. The photocatalytic properties of the obtained samples for photodegradation of RhB dye under visible light irradiation were investigated, indicating that the flowerlike BiOI hierarchical nanostructure exhibits much higher photocatalytic activity than the sphere-like BiOI nanostructures owing to the larger surface areas, higher light absorption, and better photo-induced charge separation.

Solvothermal synthesis and electrochemical performance in super-capacitors of Co3O4/C flower-like nanostructures

Novel three dimensional (3D) Co3O4/C flower-like nanostructures are synthesized via a facile solvothermal strategy. The samples are characterized by XRD, XPS, FT-IR, Raman, TG, SEM and HRTEM. The results show that the 3D flower-like nanostructures are consisted of numerous 2D nanosheets with the thickness of about 20 nm. The pseudocapacitive behaviors of Co3O4/C and bare Co3O4 flower-like nanostructures are investigated by cyclic voltammograms, galvanostatic charge–discharge and electrochemical impedance spectroscopy test. The results reveal that the Co3O4/C delivers a large specific capacitance of as high as 865 F g−1 and 330 F g−1 at 1 mV s−1 and 0.5 A g−1, according to CV and galvanostatic test, respectively; while the bare Co3O4 has a poor electrochemical performance, which exhibits specific capacitance of 131.7 F g−1 and 46.1 F g−1 at the same condition. The excellent electrochemical performance is attributed to the carbon present on the Co3O4 and the morphology, which possesses large surface area, unique flower-like nanostructures and low equivalent series resistance.

3D flower-like magnesium borate microspheres assembled by nanosheets synthesized via PVP-assisted method

We report a facile route using precipitation reaction and sequential calcination to synthesize three-dimensional (3D) flower-like magnesium borate (Mg3B2O6) nanoarchitectures with poly(vinyl pyrrolidone) (PVP) as the template. The structure and morphology were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM). The results indicate that 3D flower-like Mg3B2O6 microspheres with diameters of 0.6–1.0μm are composed of large numbers of single crystalline nanosheets with thickness of about 10nm. The N2 sorption result and pore-size distribution analysis show that mesopores and macropores exist in the 3D flower-like nanostructures. The mesopores and macropores will endow the hierarchical microspheres with novel application potentials.

Controlled fabrication of highly conductive three-dimensional flowerlike poly (3,4-ethylenedioxythiophene) nanostructures

Poly(3,4-ethylenedioxythiophene) (PEDOT) with three-dimensional (3D) flowerlike nanostructures was fabricated by chemical oxidation polymerization in a ternary phase system, which was composed of the surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT), aqueous FeCl3 solution and p-xylene. This kind of 3D flowerlike PEDOT formed by nanofibers was prepared by controlling the molar ratio of water (used to dissolve FeCl3) to the surfactant, AOT. This molar ratio is defined as N which equals nH2O/nAOT. In particular, both the conductivity and specific surface area increased with the molar ratio, N, increasing. The room temperature conductivity of the synthesized PEDOT reached a relative high value of 137 S cm−1. Moreover, the novel 3D flowerlike nanostructures endow a high specific surface area of around 46 m2 g−1. The measurements of UV-visible spectroscopy (UV-vis) and X-ray photoelectron spectroscopy (XPS) indicate that the doping level played a key role in improving conductivity of PEDOT. This study is significant to the potential applications of PEDOT on supercapacitors, sensors, actuators, transistors, and so on.

Synthesis and characterization of novel flower-like CeF 3 nanostructures via a rapid microwave method

Novel flower-like CeF 3 nanostructures with a mean diameter of 190 nm were successfully synthesized via a rapid and facile microwave irradiation route using ethylenediaminetetraacetic acid disodium as the complexing reagent. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photoluminescence (PL). XRD patterns showed that the CeF 3 nanoflowers were hexagonal phase and had good crystallinity and purity. TEM and SEM images showed that the as-prepared CeF 3 samples displayed 3D flower-like nanostructures and had uniform sizes and morphologies. The experimental results revealed that the as-prepared CeF 3 nanoflowers might be assembled by nanodisks. The formation process of the CeF 3 nanoflowers was preliminarily investigated.

Hydrothermal Synthesis and High Photocatalytic Activity of 3D Wurtzite ZnSe Hierarchical Nanostructures

Novel 3D wurtzite ZnSe hierarchical nanostructures have been synthesized by a mild hydrothermal treatment. The as-prepared flowerlike nanostructures efficiently catalyze the photodegradation of methylene blue and ethyl violet present in aqueous solutions under UV light irradiation, exhibiting higher photocatalytic activity than the commercially available photocatalysts P25 and ZnSe microspheres. We also demonstrate that flowerlike morphology is important for the excellent photocatalytic activity. The high photoactivity of the hierarchical nanoflowers can be attributed to the combined effects of several factors, namely, large surface areas, the existence of mesopores, and the high band gap energy. In addition, the photocatalysts work effectively under natural sunlight as well. To the best of our knowledge, this is the first time that wurtzite ZnSe 3D flowerlike nanostructures with high photocatalytic activity have been synthesized in solution.

ZnO 3D flower-like nanostructure synthesized on GaN epitaxial layer by simple route hydrothermal process

Abstract The 3D type, flower-like ZnO nanostructures from particle to flower-like or chestnut bur are fabricated on the GaN epitaxial layer substrate through the simple-route hydrothermal process. Structural characterization was made for the ZnO 3D nanostructures synthesized in different pH ranging from 9.5 to 11.0. The growth model was proposed and discussed regarding the fabrication mechanism and morphology of ZnO 3D flower-like nanostructure. The flower-like ZnO is composed of many thin single crystals ZnO nanorods. Bigger and thicker ZnO structure is fabricated with the increase of pH in solution. The enhanced UV emission in the PL measurement and the spectra in the Raman spectroscopy for ZnO–GaN heterojunction material were discussed.

Self‐Assembled 3D Flowerlike Iron Oxide Nanostructures and Their Application in Water Treatment

An ethylene-glycol-mediated self-assembly process is adopted to synthesize 3D flowerlike nanostructures of iron oxide (see figure) using inexpensive and nontoxic ferric chloride. A two-stage growth process is identified during the morphological evolution of the iron oxide precursor. α-Fe2O3, γ-Fe2O3, and Fe3O4 with the same flowerlike structure are readily obtained from the same precursor but by different calcination procedures. The as-obtained iron oxides show excellent ability to remove various pollutants from water.