Two-dimensional (2D) nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004, due to their intriguing physicochemical properties and wide-ranging applications in catalysis, energy-related devices, electronics and optoelectronics. To maximize the potential of 2D nanomaterials for their technological applications, controlled assembly of 2D nanobulding blocks into integrated systems is critically needed. This mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures, from in-situ assembly method to post-synthesis assembly. The applications of 2D assembled integrated structures are also covered, especially in the areas of energy, electronics and sensing, and we conclude with discussion on the remaining challenges and potential directions in this emerging field.
Utilizing vacuum-tuned-atmosphere induced dip coating method, we achieve the cross-dimensional macroscopic diverse self-assemblies by using one building block with one chemical functionality. Coordinated modulating the vacuum degree, colloid concentration and evaporation atmosphere, Au@Ag core/shell NCs can controllably assemble into diverse multi-dimensional superstructures. Under 0.08 MPa, we obtained the two-dimensional (2D) stepped superstructures with continuously tunable step width. In addition, we generated a series of tailorable nanoscale-roughened 2D Au@Ag NCs superstructures at 0.04 MPa, which exhibited the label-free ultrasensitive SERS detection for the different mutants of IAPP8-37 proteins. Under 0.01 MPa, we obtained the cross-dimensional tailorable Au@Ag NCs assemblies from random to macroscale 2D and three-dimensional (3D) densest superstructures by adjusting the capping ligand-environmental molecule interactions. This is a flexible method to generate as-prepared Au@Ag core/shell NCs into well-defined macroscopic diverse superstructures and to promote the exploitation into biological applications.
We propose a process of quantum-confined ion superfluid (QISF), which is enthalpy-driven confined ordered fluid, to explain the transmission of nerve signals. The ultrafast Na+ and K+ ions transportation through all sodium-potassium pump nanochannels simultaneously in the membrane is without energy loss, and leads to QISF wave along the neuronal axon, which acts as an information medium in the ultrafast nerve signal transmission. The QISF process will not only provide a new view point for a reasonable explanation of ultrafast signal transmission in the nerves and brain, but also challenge the theory of matter wave for ions, molecules and particles.
DNA is a self-assembled, double stranded natural molecule that can chelate and align nickel ions between its base pairs. The fabrication of a DNA-guided nickel ion chain (Ni-DNA) device was successful, as indicated by the conducting currents exhibiting a Ni ion redox reaction-driven negative differential resistance effect, a property unique to mem-elements (1). The redox state of nickel ions in the Ni-DNA device is programmable by applying an external bias with different polarities and writing times (2). The multiple states of Ni-DNA-based memristive and memcapacitive systems were characterized (3). As such, the development of Ni-DNA nanowire device-based circuits in the near future is proposed.
As a minimally invasive local cancer therapy, photothermal therapy (PTT) has aroused intensive interests in recent years. However, the therapeutic effect of PTT is still unsatisfying due to the production of heat shock proteins. Combination therapy has been regarded as a promising strategy to enhance therapeutic efficiency. In this study, a novel intelligent protoporphyrin (PpIX)-based polymer nanoplatform is developed for synergistic enhancement of cancer treatment through combined PTT and nitric oxide (NO) therapy. The core of the nanoparticle is composed of closely packed porphyrin-based NO donors and PpIX branches of the block copolymer. The prepared nanoparticles exhibit good photothermal conversion capability and high sensitivity to release NO under light illumination. And the produced high localized temperature and intracellular NO concentration could efficiently inhibit cancer cells both in vitro and in vivo. More important, this therapeutic nanoplatform can fundamentally eliminate the emergence of multidrug resistance and overcome the hypoxia microenvironment in tumors because of the absence of chemotherapeutic drugs and the oxygen-independent process, thus opening up new ideas for multifunctional therapeutic agent design for treatment of multidrug-resistant cancer.
Structure–activity relationship (SAR) is the key problem of nanoscience, thus to fabricate novel and well-defined nanostructure will provide a new insight on catalyst preparation method. Highly active and low cost electrocatalysts for oxygen evolution reaction (OER) are of great importance for future renewable energy conversion and storage. Herein, NiFe-based layered double hydroxides with laminar structure (NFLS) were successfully fabricated via a one-step hydrothermal approach by using sodium dodecyl sulfate as surfactant. The as-fabricated NFLS showed a well-defined periodic layered-stacking geometry with a scale down to 1-nm. Benefitting from the unique structure, NFLS exhibited an excellent catalytic activity towards OER with current densities of 10 mA·cm−2 at overpotential of 197 mV. The synergistic effect of Ni and Fe plays a key role in electrode reactions. The present work provides a new insight to improve the OER performance by rational design of electrocatalysts with unique structures.
Atherosclerotic plaque rupture results in thrombus formation and vessel occlusion, and is the leading cause of death worldwide. There is a pressing need to identify plaque vulnerability for the treatment of carotid and coronary artery diseases. Nanomaterials with enzyme-like properties have attracted significant interest by providing biological, diagnostic and prognostic information about the diseases. Here we showed that bioengineered magnetoferritin nanoparticles (M-HFn NPs) functionally mimic peroxidase enzyme and can intrinsically recognize plaque-infiltrated active macrophages, which drive atherosclerotic plaque progression and rupture and are significantly associated with the plaque vulnerability. The M-HFn nanozymes catalyze the oxidation of colorimetric substrates to give a color reaction that visualizes the recognized active macrophages for one-step pathological identification of plaque vulnerability. We examined 50 carotid endarterectomy specimens from patients with symptomatic carotid disease and demonstrated that the M-HFn nanozymes could distinguish active macrophage infiltration in ruptured and high-risk plaque tissues, and M-HFn staining displayed a significant correlation with plaque vulnerability (r = 0.89, P < 0.0001).
Elliptical metallic nanohole arrays possess much higher transmission and enhanced sensitivity compared with circular nanohole arrays. However, fabricating elliptical metallic nanohole arrays in large area with highly tunable aspect ratio remains a challenge. Herein, a brand-new method combining stretchable imprinting with colloidal lithography is figured out to fabricate deep-elliptical-silver-nanowell arrays (d-EAgNWAs). In this method, large area highly ordered silicon nanopillar arrays fabricated by colloidal lithography were taken as a master to transfer large area polydimethylsiloxane (PDMS) nanohole arrays. Benefit from the high elasticity of PDMS mold, the aspect ratio of d-EAgNWAs achieved can be facilely regulated from 1.7 to 5.0. Through optimization of polarization direction and the structural parameters including nanowell depth, aspect ratio, and hole size, the sensing performance of d-EAgNWAs was finally improved up to 1,414.1 nm/RIU. The best sensing behaved d-EAgNWAs were employed as an immunoassay platform finally to prove their great potential in label-free biosensing.
Graphene-h-BN hybrid nanostructures are grown in one step on the Pt(111) surface by ultra-high vacuum chemical vapor deposition using a single precursor, the dimethylamino borane complex. By varying the deposition conditions, different nanostructures ranging from a fully continuous hybrid monolayer to well-separated Janus nanodots can be obtained. The growth starts with heterogeneous nucleation on morphological defects such as Pt step edges and proceeds by the addition of small clusters formed by the decomposition of the dimethylamino borane complex. Scanning tunneling microscopy measurements indicate that a sharp zigzag in-plane boundary is formed when graphene grows aligned with the Pt substrate and consequently with the h-BN layer as well. When graphene is rotated by 30°, the graphene armchair edges are seamlessly connected to h-BN zigzag edges. This is confirmed by a thorough density functional theory (DFT) study. Angle resolved photoemission spectroscopy (ARPES) data suggests that both h-BN and graphene present the typical electronic structure of self-standing non-interacting materials.
We describe a route to the preparation of (metal yolk)/(porous ceria shell) nanostructures through the heterogeneous growth of ceria on porous metal nanoparticles followed by the calcination-induced shrinkage of the nanoparticles. The approach allows for the control of the ceria shell thickness, the metal yolk composition and size, which is difficult to realize through common templating approaches. The yolk/shell nanostructures with monometallic Pt and bimetallic PtAg yolks featuring plasmon-induced broadband light absorption in the visible region are rationally designed and constructed. The superior photocatalytic activities of the obtained nanostructures are demonstrated by the selective oxidation of benzyl alcohol under visible light. The excellent activities are ascribed to the synergistic effects of the metal yolk and the ceria shell on the light absorption, electron-hole separation and efficient mass transfer. Our synthesis of the (metal yolk)/(porous ceria shell) nanostructures points out a way to the creation of sophisticated heteronanostructures for high-performance photocatalysis.
Electrochemical N2 reduction offers a promising alternative to the Haber-Bosch process for sustainable NH3 synthesis at ambient conditions, but it needs efficient catalysts for the N2 reduction reaction (NRR). Here, we report that FeOOH quantum dots decorated graphene sheet acts as a superior catalyst toward enhanced electrocatalytic N2 reduction to NH3 under ambient conditions. In 0.1 M LiClO4, this hybrid attains a large NH3 yield rate and a high Faradaic efficiency of 27.3 µg·h−1·mg−1cat. and 14.6% at −0.4 V vs. reversible hydrogen electrode, respectively, rivalling the current efficiency of all Fe-based NRR electrocatalysts in aqueous media. It also shows strong durability during the electrolytic process.
The morphology and structural stability of metal/2D semiconductor interfaces strongly affect the performance of 2D electronic devices and synergistic catalysis. However, the structural evolution at the interfaces has not been well explored particularly at atomic resolution. In this work, we study the structural evolution of Au nanoparticles (NPs) on few-layer MoS2 by high resolution transmission electron microscope (HRTEM) and quantitative high-angle annular dark field scanning TEM. It is found that in the transition of Au from nanoparticles to dendrites, a dynamically epitaxial alignment between Au and MoS2 lattices is formed, and Moiré patterns can be directly observed in HRTEM images due to the mismatch between Au and MoS2 lattices. This epitaxial alignment can occur in ambient conditions, and can also be accelerated by the irradiation of high-energy electron beam. In situ observation clearly reveals the rotation of Au NPs, the atom migration inside Au NPs, and the transfer of Au atoms between neighboring Au NPs, finally leading to the formation of epitaxially aligned Au dendrites on MoS2. The structural evolution of metal/2D semiconductor interfaces at atomic scale can provide valuable information for the design and fabrication of the metal/2D semiconductor nano-devices with desired physical and chemical performances.
Vulnerable atherosclerotic plaques are responsible for most cardiovascular diseases (CVDs). Folate receptor (FR) positive activated macrophages were thought to be a prominent component in the development of vulnerable plaque. The objective of this study is to develop folate conjugated two-dimensional (2D) Pd@Au nanomaterials (Pd@Au-PEG-FA) for targeted multimodal imaging of the FRs in advanced atherosclerotic plaques. Pharmacokinetic and imaging studies (single photon emission computed tomography (SPECT), computed tomography (CT) and photoacoustic (PA) imaging) were performed to confirm the prolonged blood half-life and enrichment of radioactivity in atherosclerotic plaques. Strong signals were detected in vivo with SPECT, CT and PA imaging in heavy atherosclerotic plaques, which were significantly higher than those of the normal aortas after injection of Pd@Au-PEG-FA. Blocking studies with preinjection of excess FA could effectively reduce the targeting ability of Pd@Au-PEG-FA in atherosclerotic plaques, further demonstrating the specific binding of Pd@Au-PEG-FA for plaque lesions. Histopathological characterization revealed that the signal of probe was in accordance with the high-risk plaques. In summary, the Pd@Au-PEG-FA has favorable pharmacokinetic properties and provides a valuable approach for detecting high-risk plaques in the presence of FRs in atherosclerotic plaques.
Subtle structural changes during electrochemical processes often relate to the degradation of electrode materials. Characterizing the minute-variations in complementary aspects such as crystal structure, chemical bonds, and electron/ion conductivity will give an in-depth understanding on the reaction mechanism of electrode materials, as well as revealing pathways for optimization. Here, vanadium pentoxide (V2O5), a typical cathode material suffering from severe capacity decay during cycling, is characterized by in-situ X-ray diffraction (XRD) and in-situ Raman spectroscopy combined with electrochemical tests. The phase transitions of V2O5 within the 0–1 Li/V ratio are characterized in detail. The V–O and V–V distances became more extended and shrank compared to the original ones after charge/discharge process, respectively. Combined with electrochemical tests, these variations are vital to the crystal structure cracking, which is linked with capacity fading. This work demonstrates that chemical bond changes between the transition metal and oxygen upon cycling serve as the origin of the capacity fading.
Graphene nanosheets are a promising scaffold to accommodate S for achieving high performance Li/S battery. Nanosheet activation is used as a viable strategy to induce a micropore system and further improve the battery performance. Accordingly, chemical activation methods dominate despite the need of multiple stages, which slow down the process in addition to making them tiresome. Here, a three-dimensional (3D) N-doped graphene specimen was physically activated with CO2, a clean and single step process, and used for the preparation of a sulfur composite (A-3DNG/S). The A-3DNG/S composite exhibited outstanding electrochemical properties such as an excellent rate capability (1,000 mAh·g−1 at 2C), high reversible capacity and cycling stability (average capacity ~ 800 mAh·g−1 at 1C after 200 cycles), values which exceed those measured in chemically activated graphene. Therefore, these results support the use of physical activation as a simple and efficient alternative to improve the performance of carbons as an S host for high-performance Li-S batteries.
The unique structure of zero-dimensional (0D) perovskite-analogues has attracted a great amount of research interest in recent years. To date, the current compositional library of 0D perovskites is largely limited to the lead-based Cs4PbX6 (X = Cl, Br, and I) systems. In this work, we report a new synthesis of lead-free 0D Cs3BiX6 (X = Cl, Br) perovskite-analogue nanocrystals (NCs) with a uniform cubic shape. We observe a broad photoluminescence peak centered at 390 nm for the 0D Cs3BiCl6 NCs at low temperatures. This feature originates from a self-trapped exciton mechanism. In situ thermal stability studies show that Cs3BiX6 NCs remain stable upon heating up to 200 °C without crystal structural degradation. Moreover, we demonstrate that the Cs3BiX6 NCs can transform into other bismuth-based perovskite-analogues via facile anion exchange or metal ion insertion reactions. Our study presented here offers the opportunity for further understanding of the structure-property relationship of 0D perovskite-analogue materials, leading toward their future optoelectronic applications.
Lithium-sulfur batteries (LSBs) have been regarded as one of the most promising energy storage systems to break through the upper limit of lithium-ion batteries. However, the rampant diffusions of soluble lithium polysulfides (LiPSs) in the electrolyte induced the shuttle effect between anode and cathode, resulting in low sulfur utilization, low energy efficiency and short cycling life. Herein, we prove the rational design and construction of Ni nanoparticles filled in vertically grown N-doped bamboo-like carbon nanotubes (CNTs) on graphene nanosheets (Ni@NG-CNTs) as efficient polysulfide barrier for high-performance LSBs. The unique design integrates graphene nanosheets and CNTs into hierarchical architectures with one-dimensional (1D) CNTs, two-dimensional (2D) ultrathin nanosheets and abundant carbon nanocages. This design provides large surface area for lithium polysulfides (LiPSs) adsorption, accelerates electron transport and enhances electrochemical redox of LiPSs. Benefiting from the unique structural features, the LSBs with the Ni@NG-CNTs as polysulfide barrier keep high reversible specific capacities of 309.1 and 265.0 mAh·g−1 at 5 and 10 C rates after 500 cycles. This work provides a new strategy for constructing self-assembled hybrids of CNTs and graphene nanosheets with abundant carbon nanocages for high-performance LSBs.
A reproducible synthetic strategy was developed for facile large-scale (200 mg) synthesis of surface silanized magnetite (Fe3O4) nanoparticles (NPs) for biological applications. After further coupling a phosphate-specific affinity ligand, these functionalized magnetic NPs were used for the highly specific enrichment of phosphoproteins from a complex biological mixture. Moreover, correlating the surface silane density of the silanized magnetite NPs to their resultant enrichment performance established a simple and reliable quality assurance control to ensure reproducible synthesis of these NPs routinely in large scale and optimal phosphoprotein enrichment performance from batch-to-batch. Furthermore, by successful exploitation of a top-down phosphoproteomics strategy that integrates this high throughput nanoproteomics platform with online liquid chromatography (LC) and tandem mass spectrometry (MS/MS), we were able to specifically enrich, identify, and characterize endogenous phosphoproteins from highly complex human cardiac tissue homogenate. This nanoproteomics platform possesses a unique combination of scalability, specificity, reproducibility, and efficiency for the capture and enrichment of low abundance proteins in general, thereby enabling downstream proteomics applications.
Magnesium ion batteries are emerging as promising alternatives to lithium ion batteries because of their advantages including high energy density, dendrite-free features and low cost. Nevertheless, one of the major challenges for magnesium ion batteries is the kinetically sluggish magnesium insertion/extraction and diffusion in electrode materials. Aiming at this issue, biphase eutectic-like bismuth-tin film is designed herein to construct a self-supporting anode with interdigitated phase distribution and hierarchically porous structure, and further fabricated by a facile one-step magnetron cosputtering route. As benchmarked with single-phase bismuth or tin film, the biphase bismuth-tin film delivers high specific capacity (538 mAh/g at 50 mA/g), excellent rate performance (417 mAh/g at 1,000 mA/g) and good cycling stability (233 mAh/g at the 200th cycle). The superior magnesium storage performance of the sputtered bismuth-tin film could be attributed to the synergetic effect of the interdigitated bismuth/tin phase distribution, hierarchically porous structure and biphase buffering matrices, which could increase ionic transport channels, shorten diffusion lengths and reduce total volume changes.
Benzaldehyde byproduct is an imperative intermediate in the production of fine chemicals and additives. Tuning selectivity to benzaldehyde is therefore critical in alcohol oxidation reactions at the industrial level. Herein, we report a simple but innovative method for the synthesis of palladium hydride and nickel palladium hydride nanodendrites with controllable morphology, high stability, and excellent catalytic activity. The synthesized dendrites can maintain the palladium hydride phase even after their use in the chosen catalytic reaction. Remarkably, the high surface area morphology and unique interaction between nickel-rich surface and palladium hydride (β-phase) of these nanodendrites are translated in an enhanced catalytic activity for benzyl alcohol oxidation reaction. Our Ni/PdH0.43 nanodendrites demonstrated a high selectivity towards benzaldehyde of about 92.0% with a conversion rate of 95.4%, showing higher catalytic selectivity than their PdH0.43 counterparts and commercial Pd/C. The present study opens the door for further exploration of metal/metal-hydride nanostructures as next-generation catalytic materials.