Two-dimensional Nanoarchitectures Research Articles

Two-Dimensional Nanoarchitectonics of End-on Oligomers with Versatile Structures and Tunable Negative Differential Resistance.

Maximizing the molecular information density requires simultaneously functionalizing distinct monomers and their coupling connections. However, current synthesis generally focuses on distinct monomers rather than coupling reactions because the multistep reactions significantly escalate the synthetic complexity in an exponential increase. Here, we report the two-dimensional nanoarchitectures (2DNs) of end-on oligomers, with versatile molecular structures and negative differential resistance (NDR), synthesized by programmed and surface-initiated step electrosynthesis based on the simultaneous utilization of six reactions including cross- and homocouplings. The resulting vertically end-on oligomers, with similar values in thickness and molecular length, as crystalline 2DNs, exhibit subnanometer uniformity, ultrahigh compressive modulus of 40 GPa, and low-bias NDR at 0.13 V with an ultralow power consumption of down to 0.05 nW/μm2. This highly controlled electrosynthesis provides a unique dimension to enhance the structural diversity of molecular 2D nanomaterials for high-density and low-power consumption electronics.

Catalytic applications of single-atom metal-anchored hydroxides: Recent advances and perspective

Developing isolated single atomic noble metal catalysts is one of the most effective methods to maximize noble metal atom utilization efficiency and enhance catalytic performances. Layered double hydroxides (LDHs) are two-dimensional nanoarchitectures in which M3+ and M2+ sites are atomically isolated due to static repulsions, providing special anchoring sites for single noble metal atoms and enabling the tuning of catalytic activity. Herein, a comprehensive review of the advances in LDHs supported single-atom catalysts (M/LDH SACs) is presented, focusing on the synthetic strategies, structure characterization, and application of M/LDH SACs in energy devices. Strong electronic coupling between single atomic noble metal atoms and corresponding anchoring sites of LDHs determines not only the catalytic activity of M/LDH SACs but also the stability during catalytic reactions. Furthermore, a perspective is proposed to highlight the challenges and opportunities for understanding the reaction mechanism and development of highly efficient M/LDH SACs.

Biological synthesis of nanostructured ZnO as a solar-light driven photocatalyst and antimicrobial agent

A good photocatalyst should have a high surface area, a substantial absorption capacity, and a visible light active bandgap. Semi-conductive materials, particularly nanostructured ones, have recently received more attention for photocatalytic applications since they have nearly all of the properties of a perfect photocatalyst. Therefore, modern material scientists attempt to develop a cost-effective and environmentally acceptable method for nanoscale fabrication of semi-conductive materials. Herein, we fabricate a two-dimensional (2D) nanoarchitecture of ZnO by reducing zinc nitrate precursor using plant extract (Cleome brachycarpa). Flavonoids are antioxidants that are found in high amounts in the roots, leaves, and stems of Cleome brachycarpa. Crystal structure, morphological characteristics, elemental compositions, and functional group analyses of the as-synthesized ZnO sample were carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared (FTIR), and other techniques. XRD analysis confirmed that ZnO with a nano-crystallite size (18.377 nm) and a wurtzite phase had been formed successfully. The FTIR and UV–visible analyses of the as-prepared ZnO nanoarchitecture verify the nanoarchitecture's Zn–O vibrational mode and visible light-triggered band gap (2.89 eV), respectively. SEM and EDX examinations validated the sample's two-dimensional nanoarchitecture and impurity-free chemical composition, respectively. The photocatalytic efficiency of the ZnO was analyzed under solar against crystal violet dye (CV) for 70 min. Briefly, the nanostructured ZnO catalyst eliminated 88.4% CV (mineralization + adsorption) at the rate constant (k) of 0.022 min-1. Agar well diffusion was employed to evaluate the antibacterial potential of the produced ZnO sample, which proved to be effective against both G + ive and G-ive bacterial strains. ZnO's exceptional photo-mineralization and antibacterial characteristics are owing to its innovative 2D nanoarchitecture, and visible-light triggered bandgap. The production of nanostructured semi-conductive materials from naturally occurring plant products might be advocated as an environmentally friendly alternative to chemical techniques in the future.

Advanced core-shell nanostructures based on porous NiCo-P nanodiscs shelled with NiCo-LDH nanosheets as a high-performance electrochemical sensing platform

The development of robust and efficient earth-abundant electrocatalysts based on complex core-shell arrays with ordered two-dimensional nano-architectures for different electrochemical technologies is an ongoing challenge. In this matter, the fabrication of core-shell arrays with a core of bimetallic phosphides nanodisc-like building blocks has not been reported yet. Herein, advanced core-shell nanostructures consisting of porous nickel-cobalt phosphide nanodiscs (NiCo-P NDs) shelled with nickel-cobalt layered double hydroxide nanosheets (NiCo-LDH NSs) were rationally designed (NiCo-P@NiCo-LDH). The NiCo-P@NiCo-LDH core-shell nanodiscs/nanosheets have unique features such as high conductivity, large specific surface area, more contact area between nanomaterials and analyte, and numerous active sites for enhancing electrochemical performance. The electrocatalytic performance of fabricated core-shell arrays was evaluated toward electrochemical sensing of isoprenaline (IPN) as a templet. Some competencies of glassy carbon electrode coated with NiCo-P@NiCo-LDH core-shell arrays (NiCo-P@NiCo-LDH/GCE) to IPN determination are including speedy response time (∆t <1s), low detection limit (0.17 µM), wide linear range (0.5–2110 µM), long-term stability, good reproducibility, low cost, and portability. This report is promising for application in other electrochemical technologies and it will pave the way for the development of new core-shell nanostructures based on multi-metallic phosphide nanodiscs.

Multidisciplinary Materials Research in KAIST Over the Last 50 Years

Multidisciplinary Materials Research in KAIST Over the Last 50 Years

Enhancing intramolecular features and identifying defects in organic and hybrid nanoarchitectures on a metal surface at room temperature using a NaCl-functionalized scanning tunneling microscopy tip

Scanning tunneling microscopy using an NaCl-functionalised tip is a powerful method to assess the morphology of two-dimensional nanoarchitectures and their local variations of electronic properties.

Engineering porous and compact two-dimensional nanoarchitectures on surfaces taking advantage of bisterpyridine-derivatives self-assembly

The self-assembly of bis-terpyridine molecules is investigated using STM. Images reveal that close-packed as well as porous two-dimensional nanoarchitectures can be engineered by changing the molecular backbone separating the terpyridine groups.

Functional two-dimensional nanoarchitectures based on chemically converted graphene oxide and hematoporphyrin under the sulfuric acid treatment

Abstract A model photosensitizer, hematoporphyrin (HP), captured by graphene oxide (GO) nanocarrier with and without the treatment by sulfuric acid was investigated for UV–VIS absorption, luminescence properties and Raman scattering. We demonstrate that combination of optical techniques can be efficiently used to detect an interfacial structure of hematoporphyrine/graphene oxide (HP/GO) nanoensembles. Finally, stable in aqueous media at neutral pH HP/GO nanocomposite were obtained as a result of esterification reaction catalyzed by sulfuric acid. The nanocomposite with stronger absorption and emission represents a layered structure composed of hematoporphyrine oligomers adsorbed on the surface of GO in monolayer through electrostatic and π-stacking interactions. The formation of such hybrid structures, where graphene oxide plays a role of a non-toxic sheet-like nanocarrier, open the way to create a functional nanocomposites with a high level of selective emission and efficient photosensitizing ability utilizing unique graphene properties as singlet oxygen generation enhancer.

Compact Hydrogen-Bonded Self-Assembly of Ni(II)–Salen Derivative Investigated Using Scanning Tunneling Microscopy

The self-assembly of a Ni(II)–salen-derived complex bearing benzoate groups is investigated using scanning tunneling microscopy (STM) at the solid/liquid interface. STM reveals that the molecules form a two-dimensional nanoarchitecture of close-packed hydrogen-bonded chains on graphite surface. Favorable salen chain-shaped complementarity and molecular dipolar interactions appear to be at the origin of the compact molecular chain-packing.

Two-dimensional Self-assembly of Amphiphilic Peptide at the Solid/Water Interface toward a Facile Method for Metal Nanoparticle Alignment

Abstract An amphiphilic peptide that adopts a random-coil or β-sheet conformation depending on the pH of the dissolved aqueous solution forms a monolayered fiber array when a mica substrate is immersed in the random-coil solution. The random-coil peptide adsorbed on the substrate spontaneously transforms into a fibrous structure at the mica/water interface. Such specific self-assembly behavior at the solid/water interface is profitably utilized to construct a two-dimensional nanoarchitecture of gold nanoparticles.

Synthesis and Capacitive Performances of Graphene/N-Doping Porous Carbon Composite with High Nitrogen Content and Two-Dimensional Nanoarchitecture

Synthesis and Capacitive Performances of Graphene/N-Doping Porous Carbon Composite with High Nitrogen Content and Two-Dimensional Nanoarchitecture

Self-Assembly of CdTe Nanocrystals into Two-Dimensional Nanoarchitectures at the Air−Liquid Interface Induced by Gemini Surfactant of 1,3-Bis(hexadecyldimethylammonium) Propane Dibromide

In this paper, we report the self-assembly of CdTe nanocrystals into two-dimensional nanoarchitectures at the air−liquid interface induced by a gemini-type surfactant, 1,3-bis(hexadecyldimethylammo...