3D Hierarchical Nanostructures Research Articles

Hierarchical nanostructure engineering endows ammonium vanadate as high capacity and ultra-long cycle cathode for wide-temperature aqueous zinc-ion batteries

Vanadium-based materials are the most promising cathode materials for Zinc-Ion batteries (ZIBs) due to their rich crystal structures and variable valence states. However, the structural collapse during multiple cycles leads to poor cycle life. Therefore, this work develops a 3-dimensional (3D) hierarchical nanostructure NH4V4O10 microspheres composed of nanosheets by a simple hydrothermal method, which are composed of nanosheets, this hierarchical nanostructure can promote the diffusion kinetics of Zn2+ and effectively mitigate the volume change of NH4V4O10 during the charging and discharging processes. As a result, the ZIBs assembled by the NH4V4O10 cathode exhibits high specific capacity of 522.9 mAh g−1 at 0.1 A g−1 and energy density of 348.96 Wh kg−1 at 215.12 W kg−1. At 20 A g−1, the NH4V4O10//Zn aqueous ZIB has 87.2 % capacity retention after 20,000 cycles. In addition, it exhibits excellent specific capacity and cycling performance over a wide-temperature range. At 10 A g−1, the NH4V4O10//Zn aqueous ZIB only loses 5.1 % capacity after 3500 cycles at −20 °C. Even at a high temperature of 50 °C, the capacity of NH4V4O10 battery is able to maintain 95.8 % after 450 cycles. This work informs the development of aqueous ZIBs for long cycle stability in a wide temperature range.

Binding Site Programmable Self-Assembly of 3D Hierarchical DNA Origami Nanostructures.

DNA nanotechnology has broad applications in biomedical drug delivery and programmable materials. Characterization of the self-assembly of DNA origami and quantum dots (QDs) is necessary for the development of new DNA-based nanostructures. We use computation and experiment to show that the self-assembly of 3D hierarchical nanostructures can be controlled by programming the binding site number and their positions on DNA origami. Using biotinylated pentagonal pyramid wireframe DNA origamis and streptavidin capped QDs, we demonstrate that DNA origami with 1 binding site at the outer vertex can assemble multimeric origamis with up to 6 DNA origamis on 1 QD, and DNA origami with 1 binding site at the inner center can only assemble monomeric and dimeric origamis. Meanwhile, the yield percentages of different multimeric origamis are controlled by the QD:DNA-origami stoichiometric mixing ratio. DNA origamis with 2 binding sites at the αγ positions (of the pentagon) make larger nanostructures than those with binding sites at the αβ positions. In general, increasing the number of binding sites leads to increases in the nanostructure size. At high DNA origami concentration, the QD number in each cluster becomes the limiting factor for the growth of nanostructures. We find that reducing the QD size can also affect the self-assembly because of the reduced access to the binding sites from more densely packed origamis.

Heterojunction engineering decorated TiO2/ZnO three‐dimensional hierarchical structure with g‐C3N4 for solar driving water splitting

AbstractImproving the carrier separation efficiency plays a decisive role in designing and constructing a high‐efficiency photocatalysis reaction system. Derived from providing a directional transport channel for photogenerated carriers, three‐dimensional (3D) nanostructures greatly improve the charge separation efficiency. Herein, TiO2/ZnO (TZ)/g‐C3N4 3D hierarchical nanostructure was constructed to artificially simulate photosynthesis of green plants. The optimal TZ/g‐C3N4 photoanode exhibits a photocurrent density of 1.46 mA/cm2 at 1.23 V versus reversible hydrogen electrode potential, 1.6 times that of pure TiO2 (0.9 mA/cm2). Moreover, under constant illumination (100 mW/cm2), the hydrogen production reached 80 μmol/cm2 within 180 min. It is worth noting that the TZ/g‐C3N4 photoanode shows surprising stability, which is an important indicator for the practical application of the photoelectrode. The excellent photoelectrochemical performance benefits from the following two aspects: TZ nanotree structure provides a directional transport channel for photogenerated carriers, and the modification of TZ by g‐C3N4 extends the response range to the visible region.

Ionic liquid dopant induced 3D hierarchical CuO nanostructures with doped heteroatoms and highly dispersed Ag for electrochemical upgrading of 5-hydroxymethylfurfural

The electrocatalytic 5-hydroxymethylfurfural oxidation reaction (HMFOR) has received increasing attention due to its carbon–neutral and value-added chemical properties, and the development of electrocatalyst with highly active and selective is crucial. Highly dispersing metal atoms throughout the catalyst can maximize the catalytic efficiency. Here, we synthesized a 3D hierarchical CuO nanostructure induced by ionic liquid with heteroatoms doping and Ag dispersing (Ag-CuO@IL), and this self-supported catalyst can reach 10 mA cm−2 at only 1.33 V vs RHE and achieved HMF conversion of 98.5 %, FDCA yield of 97.1 % and Faraday efficiency of 92.2 %. The excellent catalytic performance of Ag-CuO@IL for HMFOR is attributed to the doped heteroatoms derived from ILs to promote electron redistribution and the generated oxygen vacancies induced by IL anions to highly disperse Ag. Also, the catalyst was the nanosheet-assembled spherical clusters with 3D nanostructure, which exposed a large number of active sites. Density functional theory calculations showed that Ag-CuO@IL possessed moderate adsorption strengths of HMF and OH–, thus facilitating the desorption of the products in the reaction process. The design that induced by ionic liquid dopant not only provides an effective and green mean for HMFOR, but also has the large potential to guide the synthesis of other catalysts with improved performances in various applications.

Highly efficient bifunctional nanofiber catalysts with 3D hierarchical nanostructures as building blocks for rechargeable Zn–air batteries

The well-distributed cobalt nanoparticles, coupled with the large specific surface area and high conductivity of the catalyst, expand the effective number of active sites to achieve high catalytic activity toward both the ORR and OER.

Cactus-like (Ni,Co)Se2 nanosheets with 3D structure decorated on the conductive substrate for efficient hydrogen evolution reaction

Transition metal selenides are a fascinating class of substitute for traditional noble metal electrocatalysts for hydrogen evolution reaction (HER). However, the monometallic selenides still have the disadvantages of low electroactive sites and electrical conductivity. To address such drawbacks, three-dimensional (3D) hierarchical nanostructures composed of bimetallic compounds have aroused great attention. In this study, cactus-like bimetallic nickel–cobalt nanosheets with a 3D nanostructure are successfully prepared on the surface of conductive substrate by a one-step hydrothermal reaction. Then a high-efficiency bimetallic catalyst ((Ni,Co)Se2/CFP) is obtained by a facile chemical vapor deposition. Benefiting from bimetallic components and the unique 3D structure, the cactus-like (Ni,Co)Se2/CFP only requires a low overpotential of 154 mV to reach the current density of 10 mA cm−2. The Tafel slope of (Ni,Co)Se2/CFP (67 mV dec−1) further shows that (Ni,Co)Se2/CFP has faster HER kinetics. Besides, the long-term stability test demonstrates the excellent durability of (Ni,Co)Se2/CFP in 0.5 M H2SO4. This research offers a useful technique and guide for improving the structure of bimetallic selenides based on transition metals to design high-efficient HER electrocatalysts.

Fabrication and characterization of copper/cobalt sulfides catalyst on nickel substrate with enhanced monopersulfate-activated degradation of industrial dyes

This research aims to create a new material based on metal sulfides which have 3D hierarchical nanostructures for the purpose of monopersulfate (MPS) activation. Notably, the creation of a 3D catalyst with a hierarchical structure involved the growth of CuCo-layered double hydroxide (LDH) upon a nickel substrate, with subsequent direct sulfurization, producing CuS/CoS/NF (CCSNF). X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen physisorption analysis, and UV–visible diffuse reflectance spectroscopy were employed to evaluate the structures, morphologies, chemical bonds, pore size distribution, surface area, and optical properties of the samples in the study. To assess the catalytic activity of the samples, the decomposition of methylene blue, methyl orange, methyl red, and rhodamine B was examined. In comparison to CuCo-LDH/NF (CCHNF) and CuCo2O4/NF (CCONF), CCSNF was demonstrated to offer enhanced chemical and physical properties, such as greater pore volume and surface area. The morphology of CCSNF is unusual in taking the form of floral bunches which comprise nano-needles on a nickel substrate surface. The catalytic degradation efficiency for CCSNF reached 99% after 1 h. This catalyst could be re-used while offering a high level of stability. Further experiments were then conducted to determine and validate the activation mechanism and pathway of dye degradation using by MPS activated by CCSNF.

3D Self‐Supported Catalyst with Multiple Active Components for Efficient Neutral Hydrogen Evolution Reaction

AbstractUp to now, the hydrogen evolution reaction (HER) are mainly investigated in strong acidic/alkaline electrolytes. However, the HER in extreme conditions shows several drawbacks, including the corrosion of electrolyzer, water pollution, and the use of expensive anion/cation exchange membranes. The HER in neutral media is desirable to address these issues. Nevertheless, the neutral HER still faces a great challenge due to its slow kinetics. Herein, we report a plasma‐assisted approach to synthesize an efficient electrocatalyst (denoted as 3D P−Mo−NiFe LDH) with multiple active components (Ni nanoparticles, Ni3Mo alloy nanoparticles, oxygen vacancies, and molybdate‐incorporated NiFe layered double hydroxide nanosheets) supported on Cu2+1O nanorod array for neutral HER. The 3D hierarchical nanostructure can endow the catalyst with enhanced mass transfer and more exposed active sites, while the multiple active components can accelerate the HER kinetics in neutral media. As expected, the 3D P−Mo−NiFe LDH exhibits outstanding HER activity (24 mV@10 mA cm−2) and excellent stability (up to 200 h) in 1 M phosphate buffer solution (PBS).

Edge-hosted CoFeB active sites with graphene nanosheets for highly selective nitrogen reduction reaction towards ambient ammonia synthesis

Electrocatalytic nitrogen reduction reaction (NRR) offers a suitable alternative to the conventional high energy intensive Haber–Bosch process for ambient ammonia (NH3) production without the release of greenhouse gases. Herein, a chemical reduction method is employed to effectively fabricate a hierarchical 3D nanostructure composed of CoFeB nanospheres precisely enveloped and interconnected with dynamically adaptable reduced graphene oxide (rGO) nanosheets for electrocatalytic NRR. Interconnected 3D CoFeB@ rGO nanostructures selectively reduced gaseous N2 to NH3 and demonstrated high Faradaic efficiency (31.6%) and NH3 yield rate (35 μg h−1 mg−1) at − 0.2 V in 0.05 M H2SO4, comparable to various state-of-the-art electrocatalytic materials for ambient NRR. Density functional theory (DFT) simulations additionally verify that interconnected CoFeB nanospheres with mechanically flexible graphene nanosheets are beneficial in lowering the energy threshold for N2 adsorption and successive protonation. First example of CoFeB@rGO heterostructures as electrocatalysts for high efficiency, pH-universal NRR to NH3 synthesis is highlighted in this study.

Hierarchical Cu Nanoarray/NiFe Hydroxide Nanostructures for Efficient Electrochemical Water Oxidation

Three-dimensional (3D) hierarchical nanostructures have shown great promise for electrocatalysis, while a conductive core is paramount to boost the ultimate catalytic activity. In the present study, hierarchical NiFe hydroxide–Cu arrays are prepared through solution etch and sequential electrolysis as the electrocatalysts for oxygen evolution reaction (OER). The electrochemically reduced Cu nanoarrays as the core provide superior conductivity for electron transfer, while the unique hierarchical 3D structure provides a large active surface area, a short ion diffusion path, and open channels for efficient gas release. The resulting NiFe hydroxide–Cu arrays on copper foam (CF) exhibit outstanding catalytic performance of 245 and 300 mV, respectively, to achieve current densities of 10 and 100 mA cm–2 in a 1 M KOH solution. A small Tafel slope of 51 mV dec–1 and superior electrochemical durability of up to 100 h are also demonstrated.

Emergence and Stability of Hierarchical Structures under Cylindrical Confinement

AbstractFocusing on the formation of hierarchical structure under cylindrical confinement, the self‐assembly of A(BC)2B multiblock copolymer of chain length N in a nanopore with size R is studied using the self‐consistent field theory. The hierarchical concentric ring (HCk), hierarchical perforated cylinder (HPk), hierarchical helix (HHk), and even hierarchical disk (HDk) is obtained with different number of mid‐thin layers k via a proposed design principle. The results show that large pore size and χAB favor the hierarchical structure with more k, while χBC prefers hierarchical structure with less k, consistent with the results of hierarchical structure in bulk. By investigating the effect of the volume fraction of the tail A block (fA), the phase transition sequence, HCk → HPk → HHk → HDk is explored, which shares the same transition of multiblock copolymer in bulk with Lk → Gk → Ck → Sk. Finally, the phase diagram with respect to the fA and R is explored, where the stability regime of these hierarchical structures is well understood. The results provide a compelling panacea for the fabrication of hierarchical 3D nanostructures under confinement.

Solvothermal synthesis of 3D hierarchical rutile TiO2 nanostructures for efficient dye-sensitized solar cells

3D hierarchical rutile TiO2 nanostructures were successfully prepared using the solvothermal method. X-ray diffraction (XRD) revealed the formation of the anatase phase. A high-resolution transmission electron microscope (HRTEM) shows that several hundred radially distributed nanofibers with a length of 1 μm were self-assembled to form a nanostructure. Current vs voltage (I-V) measurements for the cone-shaped nanostructure showed a short circuit current density (Isc) of 2.8 mA/cm2, an open circuit voltage (Voc) of 0.70 V, and the fill factor (FF) is 0.55. The efficiency obtained for cone-shaped hierarchical rutile TiO2 structures was 1.12 %.

Hierarchical covalent organic framework-foam for multi-enzyme tandem catalysis.

Covalent organic frameworks (COFs) are ideal host matrices for biomolecule immobilization and biocatalysis due to their high porosity, various functionalities, and structural robustness. However, the porosity of COFs is limited to the micropore dimension, which restricts the immobilization of enzymes with large volumes and obstructs substrate flow during enzyme catalysis. A hierarchical 3D nanostructure possessing micro-, meso-, and macroporosity could be a beneficial host matrix for such enzyme catalysis. In this study, we employed an in situ CO2 gas effervescence technique to induce disordered macropores in the ordered 2D COF nanostructure, synthesizing hierarchical TpAzo COF-foam. The resulting TpAzo foam matrix facilitates the immobilization of multiple enzymes with higher immobilization efficiency (approximately 1.5 to 4-fold) than the COF. The immobilized cellulolytic enzymes, namely β-glucosidase (BGL), cellobiohydrolase (CBH), and endoglucanase (EG), remain active inside the TpAzo foam. The immobilized BGL exhibited activity in organic solvents and stability at room temperature (25 °C). The enzyme-immobilized TpAzo foam exhibited significant activity towards the hydrolysis of p-nitrophenyl-β-d-glucopyranoside (BGL@TpAzo-foam: Km and Vmax = 23.5 ± 3.5 mM and 497.7 ± 28.0 μM min-1) and carboxymethylcellulose (CBH@TpAzo-foam: Km and Vmax = 18.3 ± 4.0 mg mL-1 and 85.2 ± 9.6 μM min-1 and EG@TpAzo-foam: Km and Vmax = 13.2 ± 2.0 mg mL-1 and 102.2 ± 7.1 μM min-1). Subsequently, the multi-enzyme immobilized TpAzo foams were utilized to perform a one-pot tandem conversion from carboxymethylcellulose (CMC) to glucose with high recyclability (10 cycles). This work opens up the possibility of synthesizing enzymes immobilized in TpAzo foam for tandem catalysis.

Recent advances in nanoflowers: compositional and structural diversification for potential applications.

In recent years, nanoscience and nanotechnology have emerged as promising fields in materials science. Spectroscopic techniques like scanning tunneling microscopy and atomic force microscopy have revolutionized the characterization, manipulation, and size control of nanomaterials, enabling the creation of diverse materials such as fullerenes, graphene, nanotubes, nanofibers, nanorods, nanowires, nanoparticles, nanocones, and nanosheets. Among these nanomaterials, there has been considerable interest in flower-shaped hierarchical 3D nanostructures, known as nanoflowers. These structures offer advantages like a higher surface-to-volume ratio compared to spherical nanoparticles, cost-effectiveness, and environmentally friendly preparation methods. Researchers have explored various applications of 3D nanostructures with unique morphologies derived from different nanoflowers. The nanoflowers are classified as organic, inorganic and hybrid, and the hybrids are a combination thereof, and most research studies of the nanoflowers have been focused on biomedical applications. Intriguingly, among them, inorganic nanoflowers have been studied extensively in various areas, such as electro, photo, and chemical catalysis, sensors, supercapacitors, and batteries, owing to their high catalytic efficiency and optical characteristics, which arise from their composition, crystal structure, and local surface plasmon resonance (LSPR). Despite the significant interest in inorganic nanoflowers, comprehensive reviews on this topic have been scarce until now. This is the first review focusing on inorganic nanoflowers for applications in electro, photo, and chemical catalysts, sensors, supercapacitors, and batteries. Since the early 2000s, more than 350 papers have been published on this topic with many ongoing research projects. This review categorizes the reported inorganic nanoflowers into four groups based on their composition and structure: metal, metal oxide, alloy, and other nanoflowers, including silica, metal-metal oxide, core-shell, doped, coated, nitride, sulfide, phosphide, selenide, and telluride nanoflowers. The review thoroughly discusses the preparation methods, conditions for morphology and size control, mechanisms, characteristics, and potential applications of these nanoflowers, aiming to facilitate future research and promote highly effective and synergistic applications in various fields.

Microwave-assisted synthesis of a ternary MoS2/carbon-FeOx composites with 3D hierarchical nanostructure for lithium-ion battery application

Microwave-assisted synthesis of a ternary MoS2/carbon-FeOx composites with 3D hierarchical nanostructure for lithium-ion battery application

Localizing electrons on atomic platinum by metal phosphides for accelerating electrocatalytic hydrogen evolution

The development of the electrical metal-support interaction for boosting alkaline hydrogen evolution reaction (HER) is essential for the high catalytic performance of Pt-based single atom catalysts (SACs). Herein, we design the Pt single atoms immobilized Ni2P nanosheet arrays on the nickel foam (PtSA-Ni2P@NF) to construct a 3D hierarchical nanostructure as an alkaline HER catalyst. It is found that the 3D continuous NF and the conductive Ni2P array support provide an efficient electron transport path for Pt single atoms, which can significantly reduce the charge transfer impedance and increase the electrochemical active sites to accelerate HER process in the alkaline electrolyte. Density functional theory calculations and structural analytical data confirm that PtSA-Ni2P@NF displays the suitable interaction between Pt single atoms and Ni2P support with the formation of Pt-P bonds at the interface, contributing to the high electric field intensity to provide more localized free electrons for accelerating H2O dissociation process to enhance the favorable H* adsorption and H2 release. The energy required to remove adsorbed H from the reaction site for our PtSA-Ni2P@NF is found to be the lowest for PtSA-Ni2P@NF (ΔE = −0.05 eV). Electrocatalytic experiments exhibit that PtSA-Ni2P@NF displays the outstanding HER activity with a low overpotential of 26 mV at a current density of 10 mA cm−2. The mass activity (19.2 mgPt−1) of PtSA-Ni2P@NF is 43.6 times higher than that of the commercial benchmark catalyst (0.4 A mgPt−1, 20 % Pt/C).

Singlet oxygen-dominated activation of peroxymonosulfate by 3D hierarchical MnO2 nanostructures for degradation of organic pollutants in water: Surface defect and catalytic mechanism

Manganese dioxide (MnO2) is attracting significant attention in the activation of persulfate for the degradation of organic pollutants in water. But the factor determining the catalytic efficiency of MnO2, and the evolution of reactive oxygen species (ROS) remain equivocal and elusive. Herein, three-dimensional (3D) hierarchical MnO2 nanostructures are synthesized via the calcination of hydrothermal product and used to active peroxymonosulfate (PMS) for degradation of acid orange 7 (AO7) in water. The results show that the calcination temperature can tune the morphology of 3D hierarchical MnO2 nanostructures from flower to urchin-like as well as phase transformation from δ-MnO2 to α-MnO2. Owing to the presence of more surface defects and surface adsorbed oxygen species, the urchin-like α-MnO2 nanostructures prepared at 500 °C (MnO2-500) deliver the best catalytic activity in activation of PMS, and 98.3 % of AO7 is degraded in 300 s. Additionally, the MnO2-500 shows wide pH applicability (3.5–9.6). Quenching tests and electron paramagnetic resonance spectra reveal that the catalytic oxidation of AO7 in the MnO2-500/PMS system is mainly mediated by the non-radical pathway, and the dominated ROS is 1O2. Besides, electrochemical experiment confirms the presence of electron transfer in the catalytic process. Density functional theory calculations indicate that the CN and CS groups of AO7 with high electron density are easily attacked by electrophilic ROS, which is further confirmed by liquid chromatography-mass spectrometry. Finally, MnO2-500 exhibits gradually enhanced catalytic activity with the increased cycle number due to the increased surface defects and the surface adsorbed oxygen. This study provides new insight into the PMS activation by MnO2-based catalyst for the remediation of organic pollutants in water.

Mn-Based Hierarchical Polyhedral 2D/3D Nanostructures MnX2 (X = S, Se, Te) Derived from Mn-Based Metal–Organic Frameworks as High-Performance Electrocatalysts for the Oxygen Evolution Reaction

Three-dimensional (3D) nanomaterials are being explored extensively to serve as efficient electrocatalyts, which can be designed through the modification of electronic states of active sites in energy conversion applications. In this work, for the first time, a series of hierarchical polyhedral 3D nanostructures of Fe-doped manganese-based chalcogenides MnX2 (X = S, Se, Te) incorporating amorphous carbon (C) is synthesized using an Mn-based metal–organic framework as the precursor via a two-step hydrothermal route. The MnX2/C hierarchical polyhedral nanostructures (HPNs) (X = S, Se, Te) display remarkable results such as lower overpotentials of 305, 276, and 246 mV at a current density of 10 mA cm–2 and small Tafel slopes of 85, 90, and 48 mV dec–1, respectively. Moreover, iron-doped MnX2 (Fe–MnX2/C-HPNs, X = S, Se, Te) display improved electrocatalytic activity, achieving lower overpotentials of 280, 246, and 210 mV at a current density of 10 mA cm–2 and smaller Tafel slopes of 85, 65, and 48 mV dec–1, respectively. The enhanced efficiency of two-dimensional (2D)/3D hierarchical polyhedral nanostructures (Fe–MnX2/C-HPNs, X = S, Se, Te) is due to the larger specific surface area, easy charge transport, and integrated amorphous carbon. Hence, the construction of exceptionally efficient and low-cost electrocatalysts could be facilitated by this MOF-template approach for multilayer nanostructured materials for future applications.

Polyol-assisted hydrothermal synthesis of Mn-doped α – Fe2O3(MFO) nanostructures: Spin disorder-induced magnetism and photocatalytic properties.

Hierarchical nanostructures play an important role in environmental clean-up and sustainability applications. The magnetic and photocatalytic characteristics of flower-like Mn-doped α-Fe2O3 nanostructures were prepared by using a polyol-assisted hydrothermal method. Crystallite sizes are in the range of 35–42 nm, and the existence of 3D hierarchical nanostructures was observed in FESEM pictures. The optical band gap energy varies between 2.08 and 2.16 eV, while XPS examination exposes the ions' charge states and validates Mn3+ inclusion in the Fe3+ lattice. At room temperature, the addition of Mn to α-Fe2O3 results in a spin disorder ferromagnetism and coercivity of about 600 Oe was achieved. Methylene blue (MB) dye solution degraded by 92% when 2.5% Mn doped with α-Fe2O3 under visible conditions for 120 min irradiation time.

3D prickle-like hierarchical NiO nanostructures with oxygen vacancies for electrochemical detection of enrofloxacin antibiotics

3D prickle-like hierarchical NiO nanostructures with oxygen vacancies for electrochemical detection of enrofloxacin antibiotics