2D Nanoarchitectures Research Articles

Seeded Heteroepitaxial Growth of Crystallizable Collagen Triple Helices: Engineering Multifunctional Two-Dimensional Core–Shell Nanostructures

Engineering free-standing 2D nanomaterials with compositional, spatial, and functional control across size regimes from the nano- to mesoscale represents a significant challenge. Herein, we demonstrate a straightforward strategy for the thermodynamically controlled fabrication of multicomponent sectored nanosheets in which each sector can be chemically and spatially addressed independently and orthogonally. Collagen triple helices, comprising collagen-mimetic peptides (CMPs), are employed as molecularly programmable crystallizable units. Modulating their thermodynamic stability affords the controlled synthesis of 2D core-shell nanostructures via thermally driven heteroepitaxial growth. Structural information, gathered from SAXS and cryo-TEM, reveals that the distinct peptide domains maintain their intrinsic lattice structure and illuminates various mechanisms employed by CMP triple helices to alleviate the elastic strain associated with the interfacial lattice mismatch. Finally, we demonstrate that different sectors of the sheet surface can be selectively functionalized using bioorthogonal conjugation chemistry. Altogether, we establish a robust platform for constructing multifunctional 2D nanoarchitectures in which one can systematically program their compositional, spatial, and functional properties, which is a significant step toward their deployment into functional nanoscale devices.

Advancements in electrochemical sensing of hydrogen peroxide, glucose and dopamine by using 2D nanoarchitectures of layered double hydroxides or metal dichalcogenides. A review.

This review (with 105references) describes the progress that has been made in the past few years in the use of 2D nanoarchitectures in electrochemical sensors for the clinically highly significant parameters hydrogen peroxide, glucose and dopamine. Following an introduction into the field, we summarize the improvements in electrochemical sensors that can be accomplished by using such nanomaterials, with a specific focus on sensors for in-vitro diagnostics. A further large section covers sensors based on the use of layered double hydroxides (LDHs), with subsections on sensors for hydrogen peroxide, glucose and dopamine. Dichalcogenides based electrochemical sensors are treated in next section, again with subsections on hydrogen peroxide, glucose and dopamine. We also summarize key sensor parameters including limits of detection, linear ranges and real time applications in pharmaceutical, environmental and clinical fields. The next section summarizes the work related to sensing of hydrogen peroxide released from different live cells as signalling molecule indicating cellular stress. The review concludes with a discussion of current challenges and future perspectives. Graphical abstract Schematic illustration of layered double hydroxides (LDHs) and dichalcogenides based electrochemical sensors for sensitive determination of hydrogen peroxide (H2O2), glucose and dopamine (DA) from biological fluids as biomarkers for early diagnosis.

A self-calibrated 2D nanoarchitecture for label-free SERS quantitation and distribution imaging of target

To achieve handy and reliable quantitative measurements of surface-enhanced Raman spectroscopy (SERS) for universal analysis, this work designs a self-calibrated 2D nanoarchitecture as a flexible sensor. This sensor consists of a self-assembled gold nanostars (AuNSs) monolayer sandwiched between two pieces of graphene, and can be easily attached on the surface of arbitrary samples. The inner AuNSs can offer a huge number of hot spots for strong Raman enhancement, and the existence of graphene further improves the stability and reproducibility of SERS signals for precise detection. By implanting Raman reporters as internal standard (IS) onto one side of the device and attaching the device with opposite side on sample surface, the distinct SERS signals from both IS and target can be quickly collected, which offers reliable quantification information of the target by IS calibration and has been demonstrated at the theoretical and experimental levels. Using carcinogenic dyestuff and agricultural fungicide as target models, this flexible nanoarchitecture realizes fast quantitative response to target in sample solution, and rapid in situ imaging of target distribution on solid surface. This sensor shows excellent reusability, good durability, and diversified structure collocation along with the simple operability, indicating great promise for fast on-site SERS detection in quantification and imaging applications.

Two-Dimensional Holey Nanoarchitectures Created by Confined Self-Assembly of Nanoparticles via Block Copolymers: From Synthesis to Energy Storage Property.

Advances in liquid-phase exfoliation and surfactant-directed anisotropic growth of two-dimensional (2D) nanosheets have enabled their rapid development. However, it remains challenging to develop assembly strategies that lead to the construction of 2D nanomaterials with well-defined geometry and functional nanoarchitectures that are tailored to specific applications. Here we report a facile self-assembly method leading to the controlled synthesis of 2D transition metal oxide (TMO) nanosheets containing a high density of holes. We utilize graphene oxide sheets as a sacrificial template and Pluronic copolymers as surfactants. By using ZnFe2O4 (ZFO) nanoparticles as a model material, we demonstrate that by tuning the molecular weight of the Pluronic copolymers we can incorporate the ZFO particles and tune the size of the holes in the sheets. The resulting 2D ZFO nanosheets offer synergistic characteristics including increased electrochemically active surface areas, shortened ion diffusion paths, and strong inherent mechanical properties, leading to enhanced lithium-ion storage properties. Postcycling characterization confirms that the samples maintain structural integrity after electrochemical cycling. Our findings demonstrate that this template-assisted self-assembly method is a useful bottom-up route for controlled synthesis of 2D nanoarchitectures, and these holey 2D nanoarchitectures are promising for improving the electrochemical performance of next-generation lithium-ion batteries.

Sandwich-like mesoporous graphene@magnetite@carbon nanosheets for high-rate lithium ion batteries

Sandwich-like mesoporous GS@Fe3O4@C nanosheets with a 2D nanoarchitecture have been successfully synthesized by one-step solvothermal treatment. Such type of 2D nanoarchitecture is made up of a number of Fe3O4 nanoparticles uniformly grown on a graphene sheet and an even amorphous carbon layer covering on their surface. The Li-cycling properties of GS@Fe3O4@C nanosheets have been evaluated by galvanostatic discharge-charge cycling and impedance spectroscopy. Results indicate that the GS@Fe3O4@C nanosheets with about 5 wt % of graphene content provides a very high discharge capacity of 913.2 mAh g−1 at a current densities of 200 mA g−1 after 100 cycles and reveals a stable discharge capacity of 483.2 mAh g−1 at a rate of 1600 mA g−1.

Tailoring the Structure of Two‐Dimensional Self‐Assembled Nanoarchitectures Based on NiII–Salen Building Blocks

The synthesis of a series of Ni(II) -salen-based complexes with the general formula of [Ni(H2 L)] (H4 L=R(2) -N,N'-bis[R(1) -5-(4'-benzoic acid)salicylidene]; H4 L1: R(2) =2,3-diamino-2,3-dimethylbutane and R(1) =H; H4 L2: R(2) =1,2-diaminoethane and R(1) =tert-butyl and H4 L3: R(2) =1,2-diaminobenzene and R(1) =tert-butyl) is presented. Their electronic structure and self-assembly was studied. The organic ligands of the salen complexes are functionalized with peripheral carboxylic groups for driving molecular self-assembly through hydrogen bonding. In addition, other substituents, that is, tert-butyl and diamine bridges (2,3-diamino-2,3-dimethylbutane, 1,2-diaminobenzene or 1,2-diaminoethane), were used to tune the two-dimensional (2D) packing of these building blocks. Density functional theory (DFT) calculations reveal that the spatial distribution of the LUMOs is affected by these substituents, in contrast with the HOMOs, which remain unchanged. Scanning tunneling microscopy (STM) shows that the three complexes self-assemble into three different 2D nanoarchitectures at the solid-liquid interface on graphite. Two structures are porous and one is close-packed. These structures are stabilized by hydrogen bonds in one dimension, while the 2D interaction is governed by van der Waals forces and is tuned by the nature of the substituents, as confirmed by theoretical calculations. As expected, the total dipolar moment is minimized.

CHISELED NICKEL HYDROXIDE NANOPLATES GROWTH ON GRAPHENE SHEETS FOR LITHIUM ION BATTERIES

The morphologies and structures of Ni ( OH )2–graphene hybrid materials were tailored by using different mineralizers in this work. It was revealed that the synergic effects of the highly oxidized graphene sheets and the mineralizers played a crucial role in controlling the morphology and structure of the nanocomposites, and Na 2 CO 3 is a very effective mineralizer for growing chiseled 2D nanoplates of Ni ( OH )2 on graphene sheets. When produced with NaOH , fragmental Ni ( OH )2 crystals with irregular shapes erratically decorated on graphene sheets. In contrast, chiseled Ni ( OH )2 hexagonal nanoplates grown on graphene sheets were obtained when Na 2 CO 3 was used as the mineralizer. These unique 2D–2D nanoarchitectures with higher contact area between the nanocrystals and graphene substrate can increase the interfacial interaction and then efficiently improve the structural stability of the composite material, thus exhibiting an enhanced Li storage capacity and excellent cycling performance of 562 mAh g-1 after the 36th cycle.

Tailored Formation of N-Doped Nanoarchitectures by Diffusion-Controlled on-Surface (Cyclo)Dehydrogenation of Heteroaromatics

Surface-assisted cyclodehydrogenation and dehydrogenative polymerization of polycyclic (hetero)aromatic hydrocarbons (PAH) are among the most important strategies for bottom-up assembly of new nanostructures from their molecular building blocks. Although diverse compounds have been formed in recent years using this methodology, a limited knowledge on the molecular machinery operating at the nanoscale has prevented a rational control of the reaction outcome. We show that the strength of the PAH-substrate interaction rules the competitive reaction pathways (cyclodehydrogenation versus dehydrogenative polymerization). By controlling the diffusion of N-heteroaromatic precursors, the on-surface dehydrogenation can lead to monomolecular triazafullerenes and diazahexabenzocoronenes (N-doped nanographene), to N-doped oligomeric or polymeric networks, or to carbonaceous monolayers. Governing the on-surface dehydrogenation process is a step forward toward the tailored fabrication of molecular 2D nanoarchitectures distinct from graphene and exhibiting new properties of fundamental and technological interest.

A novel precursor-derived one-step growth approach to fabrication of highly antireflective, mechanically robust and self-healing nanoporous silica thin films

A novel precursor-derived one-step growth (POG) approach has been developed to fabricate highly antireflective, mechanically robust and self-healing nanoporous silica thin films. The nanoporous silica thin films were uniform and smooth with low roughness. Their transmittance decreased with the increase of exposure time to wet air, but it could completely self-heal after exposure to dry air. The key to achieving the antireflective nanoporous silica thin films is to control the growth time, CTAB/TEOS ratio and reaction temperature in the Stober solution. The maximum transmittance of coated substrates reached as high as 99.2%. The thin film coated glass substrates also exhibited excellent reduced reflection at high incident angles in addition to a significant reduction in broadband reflection. Meanwhile the thin films have excellent mechanical strength and stability (passed the 6H pencil hardness test, sand flow test and washability test). The current approach is facile, effective and versatile, and may open a new avenue to advanced multifunctional optical films of varied compositions and other 2D nanoarchitectures, and provide many new and exciting opportunities in the fabrication of functional devices for optics, electronics, optoelectronics, electrochemistry, molecule separation, and so on.