A diverse range of remarkable boron nitride (BN) nanostructures subsuming nano-horns, nano-rods, nano-platelets, and clusters of hollow nanospheres (nano-onions, arguably of greatest applied and fundamental interest) have been produced exclusively from crystalline BN precursor powder via lamp ablation. The procedure is safe, devoid of toxic reagents, simple, rapid and scalable—generating some genres of nanoparticles that had previously proved elusive. Product structure and composition were unambiguously assessed by high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy.
The capping agents for liquid metal (LM) nanodroplets in aqueous solutions are restricted to thiol-containing and positively-charged molecules or macromolecules. However, both thiolate-metal complex and electrostatic interaction are liable to detachment upon strong mechanical forces such as sonication, leading to limited stability and applications. To address this, we utilized ultrasmall water soluble melanin nanoparticles (MNPs) as the capping agent, which exhibited strong metal binding capability with the oxide layer of gallium based LMs and resulted in enhanced stability. Interestingly, shape-controlled synthesis of LM nanodroplets can be achieved by the incorporation of MNPs. Various EGaIn nanostructures including nanorice, nanosphere and nanorod were obtained by simply tuning the feed ratio, sonication time, and suspension temperature. Among these shapes, EGaIn nanorice has the best photothermal conversion efficiency, which could be leveraged for photothermal therapy.
Nanoparticles (NPs) which are innovation and research focus in drug delivery systems, still have some disadvantages limiting its application in clinical use, such as short circulation time, recognition and clearance by reticuloendothelial system (RES) and passive targeting in certain organs. However, the recent combination of natural components and nanotechnology has offered new solutions to address these problems. A novel biomimetic platform consisting of nanoparticle core and membrane shell, such as cell membrane, exosome or vesicle vastly improves properties of nanoparticles. These coated nanoparticles can replicate the unique functions of the membrane, such as prolonged blood circulation, active targeting capability and enhanced internalization. In this review, we focus on the newest development of biological-camouflaged nanoparticles and mainly introduce its application related to cancer therapy and toll-like receptor.
Anisotropic two-dimensional (2D) materials exhibit lattice-orientation dependent optical and electrical properties. Carriers doping of such materials has been used to modulate their energy band structures for opto-electronic applications. Herein, we show that by stacking monolayer rhenium disulfide (ReS2) on a flat gold film, the electrons doping in ReS2 can affect the in-plane anisotropic Raman enhancement of molecules adsorbed on ReS2. The change of enhancement factor and the degree of anisotropy in enhancement with layer number are sensitively dependent on the doping level of ReS2 by gold, which is further confirmed by Kelvin probe force microscopy (KPFM) measurements. These findings could open an avenue for probing anisotropic electronic interactions between molecules and 2D materials with low symmetry using Raman enhancement effect.
We present a new scheme for visibly-opaque but near-infrared-transmitting filters involving 7 layers based on one-dimensional ternary photonic crystals, with capabilities in reaching nearly 100% transmission efficiency in the near-infrared region. Different decorative reflection colors can be created by adding additional three layers while maintaining the near-infrared transmission performance. In addition, our proposed structural colors show great angular insensitivity up to ±60° for both transverse electric and transverse magnetic polarizations, which are highly desired in various fields. The facile strategy described here involves a simple deposition method for the fabrication, thereby having great potential in diverse applications such as image sensors, anti-counterfeit tag, and optical measurement systems.
Small-sized bimetallic nanoparticles that possess numerous accessible metal sites and optimal geometric/electronic structures show great promise for advanced synergetic catalysis but remain synthetic challenge so far. Here, an universial synthetic method is developed for building a library of bimetallic nanoparticles on mesoporous sulfur-doped carbon supports, consisting of 24 combinations of 3 noble metals (that is, Pt, Rh, Ir) and 7 other metals, with average particle sizes ranging from 0.7 to 1.4 nm. The synthetic strategy is based on the strong metal-support interaction arising from the metal-sulfur bonding, which suppresses the metal aggregation during the H2-reduction at 700 °C and ensure the formation of small-sized and alloyed bimetallic nanoparticles. The enhanced catalytic properties of the ultrasmall bimetallic nanoparticles are demonstrated in the dehydrogenation of propane at high temperature and oxidative dehydrogenations of N-heterocycles.
Oxygen evolving catalyst (OEC) is a critical determinant for the efficiency of photoelectrochemical (PEC) water splitting. Here we report an approach to depositing a novel manganese borate (Mn-Bi) OER catalyst on BiVO4 nanocone photoanode by photodeposition in sodium borate buffer solution containing Mn(II) ions. Due to the spontaneous photo-electric-field-enhancement effect at the vertically oriented BiVO4 nanocone structure, spherical Mn-Bi nanoparticle was selectively photodeposited at the apex of BiVO4 nanocone. Significant improvement of photocurrent was observed for the obtained hierarchical Mn-Bi/BiVO4 photoanode which could be ascribed to enhanced hole injection efficiency, especially in low bias region. It was observed that the injection efficiency of Mn-Bi/BiVO4 is 98% which gave a photocurrent of 0.94 mA/cm2 at 1.5 V vs. RHE.
DNA-based nanofabrication of inorganic nanostructures has potential application in electronics, catalysis, and plasmonics. Previous DNA metallization has generated conductive DNA-assembled nanostructures; however, the use of semiconductors and the development of well-connected nanoscale metal—semiconductor junctions on DNA nanostructures are still at an early stage. Herein, we report the first fabrication of multiple electrically connected metal—semiconductor junctions on individual DNA origami by location-specific binding of gold and tellurium nanorods. Nanorod attachment to DNA origami was via DNA hybridization for Au and by electrostatic interaction for Te. Electroless gold plating was used to create nanoscale metal—semiconductor interfaces by filling the gaps between Au and Te nanorods. Two-point electrical characterization indicated that the Au—Te—Au junctions were electrically connected, with current—voltage properties consistent with a Schottky junction. DNA-based nanofabrication of metal—semiconductor junctions opens up potential opportunities in nanoelectronics, demonstrating the power of this bottom-up approach.
Carbon coating has been a routine strategy for improving the performance of Si-based anode materials for lithium-ion batteries. The ability to tailor the thickness, homogeneity and graphitization degree of carbon-coating layers is essential for addressing issues that hamper the real applications of Si anodes. Herein, we report the construction of two-dimensional (2D) assemblies of interconnected Si@graphitic carbon yolk-shell nanoparticles (2D-Si@gC) from commercial Si powders by exploiting oleic acid (OA). The OA molecules act as both the surface-coating ligands for facilitating 2D nanoparticle assembly and the precursor for forming uniform and conformal graphitic shells as thin as 4 nm. The as-prepared 2D-Si@gC with rationally designed void space exhibits excellent rate capability and cycling stability when used as anode materials for lithium-ion batteries, delivering a capacity of 1,150 mAh·g−1 at an ultrahigh current density of 10 A·g−1 and maintaining a stabilized capacity of 1,275 mAh·g−1 after 200 cycles at 4 A·g−1. The formation of yolk-shell nanoparticles confines the deposition of solid electrolyte interphase (SEI) onto the outer carbon shell, while simultaneously providing sufficient space for volumetric expansion of Si nanoparticles. These attributes effectively mitigate the thickness variations of the entire electrode during repeated lithiation and delithiation, which combined with the unique 2D architecture and interconnected graphitic carbon shells of 2D-Si@gC contributes to its superior rate capability and cycling performance.
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.
Oligo(p-phenyleneethynylene)s (OPEs) end-capped with (alkynyl)bis(diphosphine)ruthenium and thiol/thiolate groups stabilize ca. 2 nm diameter gold nanoparticles (AuNPs). The morphology, elemental composition and stability of the resultant organometallic OPE/AuNP hybrid materials have been defined using a combination of molecular- and nano-material chacterization techniques. The hybrids display long-term stability in solution (more than a month), good solubility in organic solvents, reversible ruthenium-centered oxidation, and transparency beyond 800 nm, and possess very strong nonlinear absorption activity at the first biological window, and unprecedented two-photon absorption activity in the second biological window (σ2 up to 38,000 GM at 1,050 nm).
A novel tri-layer approach for immobilizing metal nanoparticles in SiO2 supports is presented. In this work, we show that under rapid heating to temperatures of approximately 1,000 °C, metal nanoparticles less than 15 nm in size will entrench in the SiO2 layer on a silicon wafer to create pores as deep as 250 nm. We studied and characterized this entrenching behavior and subsequent nanopore formation for a wide variety of metal nanoparticles, including Au, Ag, Pt, Pd, and Cu. We also demonstrate that an Al2O3 layer acts as a barrier to such pore formation. Thus, by creating a tri-layer architecture consisting of SiO2 on Al2O3 on silicon wafers, we can control the depth to which nanoparticles entrench between 3–5 nm. This small range allows one to entrench particles for the purpose of immobilization but still present them above the surface. The two advances of moving into the sub-15 nm size regime and of controlled particle immobilization through entrenchment have important implications in studying site-isolated and stabilized metal nanoparticles for applications in sensing, separations, and catalysis.
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.
Lithium metal anode for batteries has attracted extensive attentions, but its application is restricted by the hazardous dendritic Li growth and dead Li formation. To address these issues, a novel Li anode is developed by infiltrating molten Li metal into conductive carbon cloth decorated with zinc oxide arrays. In carbonate-based electrolyte, the symmetric cell shows no short circuit over 1,500 h at 1 mA·cm−2, and stable voltage profiles at 3 mA·cm−2 for ∼ 300 h cycling. A low overpotential of ∼ 243 mV over 350 cycles at a high current density of 10 mA·cm−2 is achieved, compared to the seriously fluctuated voltage and fast short circuit in the cell using bare Li metal. Meanwhile, the asymmetric cell withstands 1,000 cycles at 10 C (1 C = 167 mAh·g−1) compared to the 210 cycles for the cell using bare Li anode. The excellent performance is attributed to the well-regulated Li plating/stripping driven from the formation of LiZn alloy on the wavy carbon fibers, resulting in the suppression of dendrite growth and pulverization of the Li electrode during cycling.
Nanoparticle photosensitizers possess technical advantages for photocatalytic reactions due to enhanced light harvesting and efficient charge transport. Here we report synthesis of semiconductor nanoparticles through covalent coupling and assembly of metalloporphyrin with condensed carbon nitride. The resultant nanoparticles consist of light harvesting component from the condensed carbon nitride and photocatalytic sites from the metalloporphyrins. This synergetic particle system effectively initiates efficient charge separation and transport and exhibits excellent photocatalytic activity for CO2 reduction. The CO production rate can reach up to 57 µmol/(gh) with a selectivity of 79% over competing H2 evolution. Controlled experiments demonstrate that the combination of light harvesting with photocatalytic activity via covalent assembly is crucial for the high photocatalytic activity. Due to effective charge separation and transfer, the resultant nanoparticle photocatalysts show exceptional photo stability against photo-corrosion under light irradiation, enabling for long-term utilization. This research opens a new way for the development of stable, effective nanoparticle photocatalysts using naturally abundant porphyrin pigments.
Electronic sensors based on biomaterials can lead to novel green technologies that are low cost, renewable, and eco-friendly. Here we demonstrate bioelectronic ammonia sensors made from protein nanowires harvested from the microorganism Geobacter sulfurreducens. The nanowire sensor responds to a broad range of ammonia concentrations (10 to 106 ppb), which covers the range relevant for industrial, environmental, and biomedical applications. The sensor also demonstrates high selectivity to ammonia compared to moisture and other common gases found in human breath. These results provide a proof-of-concept demonstration for developing protein nanowire based gas sensors for applications in industry, agriculture, environmental monitoring, and healthcare.
Two-dimensional nanosheet membranes with responsive nanochannels are appealing for controlled mass transfer/separation, but limited by everchanging thicknesses arising from unstable interfaces. Herein, an interfacially stable, thermo-responsive nanosheet membrane is assembled from twin-chain stabilized metal-organic framework (MOF) nanosheets, which function via two cyclic amide-bearing polymers, thermo-responsive poly(N-vinyl caprolactam) (PVCL) for adjusting channel size, and non-responsive polyvinylpyrrolidone for supporting constant interlayer distance. Owing to the microporosity of MOF nanosheets and controllable interface wettability, the hybrid membrane demonstrates both superior separation performance and stable thermo-responsiveness. Scattering and correlation spectroscopic analyses further corroborate the respective roles of the two polymers and reveal the microenvironment changes of nanochannels are motivated by the dehydration of PVCL chains.
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.
A strategy has been developed for analyzing growth kinetics of colloidal metal nanoparticle quantitatively by focusing both the very early and the very late growth stages, at which the size of growing nanoparticles and the reaction time follow linear functions. Applying this extreme-condition model to a microwave-assistant synthesis of colloidal silver nanoparticles, for the first time, results in the determination of intrinsic kinetics parameters involving in the growth of the silver nanoparticles. The diffusion coefficient (D) of the precursor species containing Ag+ is 4.9 × 10–14 m2/s and the surface reaction rate constant (k) of the precursor species on the surface of the growing silver nanoparticles is 8.7 × 10–8 m/s in an ethylene glycol solution containing 0.15 M polyvinylpyrrolidone at 140 °C. The extreme-condition model is ready to deconvolute the intrinsic kinetics parameters of growing colloidal nanoparticles once the enlargement rate of the nanoparticles can be experimentally measured in real time and with high temporal resolution. Availability of the high-fidelity values of k and D will provide the crucial information to guide the design and synthesis of colloidal metal nanoparticles with the desirable properties.
Recovered carbon black (rCB), a very economical and abundance source of material, is transformed into dazzling multicolour fluorescence and visual display for the first time by way of a scanning focused laser treatment. This laser-initiated process is both straightforward and versatile, catering to both micro- and macro-scopic patterning with the sample in ambient or helium environment. The observed phenomenon is attributed to both chemical and structural induced colouration of rCB powder. Chemically, carbon infusion of oxidised metal occurs when photothermal reaction takes place in ambient. After laser modification with the sample in helium environment, the powder not only fluoresces due to sulphur impurities, control annealing of these powders results in formation of periodic arrangements of carbon nanoparticles. The periodicity of these arrangement falls within the range of visible wavelength, hence contributing to the visually observable rainbow coloured rCB flakes. The patterned sample is also transferrable using PDMS stamps. This in turn broadens the application of this material in flexible electronic devices/displays. Photocurrent measurements show most significant enhancement under yellow light illumination. Furthermore, in the presence of an applied potential, the fluorescence detected from the sample can easily be switched off. All in all, we present a simple process to add multiple functionalities to a material that is both inexpensive and sustainable.