Nanorod Core Research Articles

Core-shell CdS@MnS nanorods as highly efficient photocatalysts for visible light driven hydrogen evolution

This work provides a hydrothermal method to synthesize noble-metal-free materials core-shell CdS@MnS nanorods as catalysts for photocatalytic hydrogen evolution. To characterize the hydrothermally synthesized products, XRD, UV–vis DRS, TEM, HRTEM and XPS were carried out. Extraordinarily high hydrogen evolution rate under visible light irradiation (λ ≥ 400 nm) can be achieved. TEM images show that MnS is uniformly coated on the surface of CdS nanorods. The hydrogen evolution results show that coated MnS can significantly improve the photocatalytic efficiency of CdS nanorods. The hydrogen evolution rate reaches an optimal value up to 15.55 mmol g−1h−1 with MnS content of 5 wt% and is about 3.44 times higher than that of bare CdS nanorods. The large and intimate coaxial heterojunction between CdS nanorod core and MnS thin shell benefits the separation and transportation of photo-induced charge carriers.

Superstructural Raman Nanosensors with Integrated Dual Functions for Ultrasensitive Detection and Tunable Release of Molecules

It is highly desirable but extremely difficult to actively control the release dynamics of molecules from nanoparticle carriers and monitor the release process in real time. In this work, we report the design, fabrication, and manipulation of a superstructural Raman nanosensor, offering integrated dual functions in ultrasensitive biodetection and dynamic control in molecule release. The device has a designed porous superstructure consisting of gold (Au) nanorod cores and silica shells embedded with arrays of nanocavities arranged in concentric layers in three-dimensions (3D), where high-density plasmonic silver (Ag) nanoparticles are grown both in the nanocavities and on the outer surfaces. The Ag nanoparticles provide substantially enhanced Raman sensitivity for detection of molecules owing to the large number of hotspots as well as the near-field coupling of Ag nanoparticles due to their 3D concentric arrangement. Furthermore, by controlling the external electric field, the release of molecules can be f...

Direct Chemical Vapor Deposition Growth of Monolayer MoS2 on TiO2 Nanorods and Evidence for Doping-Induced Strong Photoluminescence Enhancement

Herein, we demonstrate a simple technique to control the population of nonradiative trions and radiative neutral excitons in single-layer MoS2 to enhance its photoluminescence (PL) emission by forming a core–shell heterostructure (HS) of MoS2 on TiO2 nanorods (NRs). The monolayer MoS2 (1L-MoS2) shell is grown directly on a hydrothermally grown TiO2 NR core by chemical vapor deposition, and the HS shows a strong enhancement of PL intensity by about 2 orders of magnitude over the pristine 1L-MoS2 at room temperature. The enhancement of PL in the HS is attributed, first, to the p-doping in the MoS2 lattice through charge transfer from MoS2 to TiO2, and, second, to the radiative recombination of excitons which dominates over the nonradiative ones in the HS, as confirmed by the low-temperature PL analysis. The enhancement of PL because of the p-doping effect in the bare 1L-MoS2 has been confirmed by the oxygen plasma treatment causing the adsorption of oxygen molecules at the defect sites of MoS2, as revealed ...

Rattle-Structured Rough Nanocapsules with in-Situ-Formed Gold Nanorod Cores for Complementary Gene/Chemo/Photothermal Therapy.

The morphology of nanoparticles influences their cellular uptake process, while rough surface-enhanced affinity renders rough nanoparticles desirable in related biomedical applications. In this work, rattle-structured rough nanocapsules (Au@HSN-PGEA, AHPs) composed of in-situ-formed gold nanorod (Au NR) cores and polycationic mesoporous silica shells were constructed for trimodal complementary cancer therapy. Taking advantage of surface roughness, near-infrared (NIR) responsiveness, and controlled release manner, AHPs were expected to realize the co-delivery of sorafenib (SF, a hydrophobic antiproliferative and antiangiogenic drug) and antioncogene p53 for malignant hepatocellular carcinoma treatment. The rough surface feature of AHP was investigated for cellular uptake and the subsequent gene transfection. The feasibility of photothermal Au NR cores for NIR-triggered SF release was also tested. Notably, synergistic effects based on photothemal therapy-enhanced chemotherapy were achieved. In addition, the good in vivo performance of the proposed multifunctional nanoparticles with rough surfaces was also demonstrated. The current work extends the biomedical applications of the intriguing rough nanoparticles and provides a facile strategy to construct flexible platforms for complementary gene/chemo/photothermal therapy.

Coordination-responsive drug release inside gold nanorod@metal-organic framework core–shell nanostructures for near-infrared-induced synergistic chemo-photothermal therapy

Multifunctional core–shell nanostructures formed by integration of distinct components have received wide attention as promising biological platforms in recent years. In this work, crystalline zeolitic imidazolate framework-8 (ZIF-8), a typical metal-organic framework (MOF), is coated onto single gold nanorod(AuNR) core for successful realization of synergistic photothermal and chemotherapy triggered by near-infrared (NIR) light. Impressively, high doxorubicin hydrochloride (DOX) loading capacity followed by pH and NIR light dual stimuli-responsive DOX release can be easily implemented through formation and breakage of coordination bonds in the system. Moreover, under NIR laser irradiation at 808 nm, these novel AuNR@MOF core–shell nanostructures exhibit effective synergistic chemo-photothermal therapy both in vitro and in vivo, confirmed by cell treatment and tumor ablation via intravenous injection.

(Invited) Progress in Gradient Cathode Materials for High-Performance Rechargeable Lithium-Ion Batteries

High-energy-density rechargeable batteries are needed to fulfill various demands such as self-monitoring analysis and reporting technology (SMART) devices, energy storage systems, and (hybrid) electric vehicles. As a result, high-energy electrode materials enabling a long cycle life and reliable safety need to be developed. To ensure these requirements, new material chemistries can be derived from combinations of at least two compounds in a secondary particle with varying chemical composition and primary particle morphologies having a core−shell structure and spherical cathode-active materials, specifically a nanoparticle core and shell, nanoparticle core and nanorod shell, and nanorod core and shell. To this end, several layer gradient cathode materials were developed to ensure high capacity, reliability, and safety. One of the most promising oxides is full concentration gradient (FCG) lithium nickel-cobalt-manganese oxide composed of a Mn-rich outer surface providing excellent safety and Ni-rich center achieving high capacity. In addition, we extended the FCG concept and report a new novel Li[NixCoyMnz]O2 cathode material with two-sloped full concentration gradients (TSFCG) of Ni, Co, and Mn ions throughout the cathode particles to maximize the average Ni concentration at the core as active redox species and the Mn concentration in the area near the particle surface. Comparison of electrochemical and thermal properties of the TSFCG with those of NCA and conventional cathode Li[NixCoyMnz]O2 is presented.

Coordination-Responsive Drug Release inside Gold Nanorod@MOF for NIR-Induced Synergistic Chemo-Photothermal Therapy

Multifunctional core-shell nanostructures by integration of distinct components have received wide attention as a promising biological platform in recent years. In this work, the crystalline zeolitic imidazolate framework-8 (ZIF-8), a typical metal-organic framework (MOF), is coated onto single gold nanorod (AuNR) core for successful realization of synergistic photothermal and chemotherapy triggered by near-infrared (NIR) light. Impressively, the high doxorubicin hydrochloride (DOX) loading capacity followed by pH and NIR light dual stimuli-responsive DOX release can be easily implemented through formation and breakage of coordination bonds in the system. Moreover, under 808 nm NIR laser irradiation, these novel core-shell NP@MOF nanostructures exhibit effective chemo-photothermal synergistic therapy both in vitro and in vivo, confirmed by both cell treatment and tumor ablation via intravenous injection.

Construction of CdS@UIO-66-NH2 core-shell nanorods for enhanced photocatalytic activity with excellent photostability

A novel class of CdS@UIO-66-NH2 core shell heterojunction was fabricated by the facile in-situ solvothermal method. Characterizations show that porous UIO-66-NH2 shell not only allows the visible light to be absorbed on CdS nanorod core, but also provides abundant catalytic active sites as well as an intimate heterojunction interface between UIO-66-NH2 shell and CdS nanorod core. By taking advantage of this property, the core-shell composite presents highly solar-driven photocatalytic performance compared with pristine UIO-66-NH2 and CdS nanorod for the degradation of organic dyes including malachite green (MG) and methyl orange (MO), and displays superior photostability after four recycles. Furthermore, the photoelectrochemical performance of CdS@UIO-66-NH2 can be measured by the UV–vis spectra, Mott-Schottky plots and photocurrent. The remarkably enhanced photocatalytic activity of CdS@UIO-66-NH2 can be ascribed to high surface areas, intimate interaction on molecular scale and the formation of one-dimensional heterojunction with n-n type. What’s more, the core-shell heterostructural CdS@UIO-66-NH2 can facilitate the effective separation and transfer of the photoinduced interfacial electron-hole pairs and protect CdS nanorod core from photocorrosion.

Synthesis of novel MnOx@TiO2 core-shell nanorod catalyst for low-temperature NH3-selective catalytic reduction of NOx with enhanced SO2 tolerance

In this study, a MnOx@TiO2 core-shell catalyst prepared by a two-step method was used for the low-temperature selective catalytic reduction of NOx with NH3. The catalyst exhibits high activity, high stability, and excellent N2 selectivity. Furthermore, it displays better SO2 and H2O tolerance than its MnOx, TiO2, and MnOx/TiO2 counterparts. The prepared catalyst was characterized systematically by transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Raman, BET, X-ray photoelectron spectroscopy, NH3 temperature-programmed desorption and H2 temperature-programmed reduction analyses. The optimized MnOx@TiO2 catalyst exhibits an obvious core-shell structure, where the TiO2 shell is evenly distributed over the MnOx nanorod core. The catalyst also presents abundant mesopores, Lewis-acid sites, and high redox capability, all of which enhance its catalytic performance. According to the XPS results, the decrease in the number of Mn4+ active centers after SO2 poisoning is significantly lower in MnOx@TiO2 than in MnOx/TiO2. The core-shell structure is hence able to protect the catalytic active sites from H2O and SO2 poisoning.

Light-Responsive Polymer Particles as Force Clamps for the Mechanical Unfolding of Target Molecules

Single-molecule force spectroscopy techniques are powerful tools for investigating the mechanical unfolding of biomolecules. However, they are limited in throughput and require dedicated instrumentation. Here, we report a force-generating particle that can unfold target molecules on-demand. The particle consists of a plasmonic nanorod core encapsulated with a thermoresponsive polymer shell. Optical heating of the nanorod leads to rapid collapse of the polymer, thus transducing light into mechanical work to unfold target molecules. The illumination tunes the duration and degree of particle collapse, thus controlling the lifetime and magnitude of applied forces. Single-molecule fluorescence imaging showed reproducible mechanical unfolding of DNA hairpins. We also demonstrate the triggering of 50 different particles in <1 min, exceeding the speed of conventional atomic force microscopy. The polymer force clamp represents a facile and bottom-up approach to force manipulation.

Sacrificial-template-free synthesis of core-shell C@Bi2S3 heterostructures for efficient supercapacitor and H2 production applications

Core-shell heterostructures have attracted considerable attention owing to their unique properties and broad range of applications in lithium ion batteries, supercapacitors, and catalysis. Conversely, the effective synthesis of Bi2S3 nanorod core@ amorphous carbon shell heterostructure remains an important challenge. In this study, C@Bi2S3 core-shell heterostructures with enhanced supercapacitor performance were synthesized via sacrificial- template-free one-pot-synthesis method. The highest specific capacities of the C@Bi2S3 core shell was 333.43 F g−1 at a current density of 1 A g−1. Core-shell-structured C@Bi2S3 exhibits 1.86 times higher photocatalytic H2 production than the pristine Bi2S3 under simulated solar light irradiation. This core-shell feature of C@Bi2S3 provides efficient charge separation and transfer owing to the formed heterojunction and a short radial transfer path, thus efficiently diminishing the charge recombination; it also facilitates plenty of active sites for the hydrogen evolution reaction owing to its mesoporous nature. These outcomes will open opportunities for developing low-cost and noble-metal-free efficient electrode materials for water splitting and supercapacitor applications.

Probing conducting polymers@cadmium sulfide core-shell nanorods for highly improved photocatalytic hydrogen production

We report three types of conducting polymers (CPs), polyaniline (PANI), polypyrrole (PPY) and poly (3,4-ethylenedioxythiophene) (PEDOT) to modify the surface of the CdS nanorods to probe their photocorrosion inhibition and photocatalytic hydrogen production. Various characterizations, such as high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and density function theory (DFT) calculations have been conducted to reveal the intrinsic structure of the as-constructed CPs@CdS (@ means CPs at the surface of CdS) core-shell nanorods. The results show that the PANI and PPY shells with abundant N and C atoms can significantly enhance the binding energy of Cd and S atoms on the surface of the CdS nanorods. However, there is no obvious enhancement of binding energy at the interface of the PEDOT shell and the CdS nanorods core. Therefore, PANI@CdS and PPY@CdS possess stronger driving force than PEDOT@CdS to inject the photogenerated holes in conducting polymer shells. As a result, the polyaniline (PANI) modified PANI@CdS core-shell nanorods demonstrate the most effectively enhanced hydrogen production rate of ∼9.7 mmol h−1 g−1 and effective photocorrosion inhibition in 30 h without deactivation under visible-light irradiation. The hydrogen production performance of PPY@CdS is not effectively promoted owing to the weak transmittance of light for the PPY shell. The PEDOT shell cannot improve the hydrogen production and stability property of the CdS nanorods. This work could shed some light on conducting polymers modifying metal sulfides nanostructures that is of inconceivable significance for effective photocorrosion inhibition and highly enhanced photocatalytic activities.

Preparation of dye-sensitized solar cells using template free TiO2 nanotube arrays for enhanced power conversion

By using the vertically aligned ZnO nanorod arrays (NRAs), TiO2 nanoparticles attached ZnO nanorods (TiO2@ZnO) and TiO2 nanotube arrays (NTAs) were prepared from feasible seed-induced template free sol-gel dip coating method. TiO2 NTAs were prepared by removing the ZnO nanorod cores using wet-chemical etching. By using TiO2 NTAs as working electrode, dye-sensitized solar cell with enhanced power conversion efficiency was obtained. To verify the formation of TiO2 NTAs various characterization techniques such as X-ray diffraction, UV-VIS absorbance spectra, Field Emission Scanning Electron Microscopy (FESEM), Energy-Dispersive Spectra (EDS), and High-Resolution Transmission Electron Microscopy (HRTEM) have been used. X-ray diffraction patterns of ZnO NRAs and TiO2@ZnO NRAs indicate that prepared films possess both the ZnO wurtzite (002) and TiO2 anatase (101) phase. FESEM image clearly shows that vertically aligned ZnO nanorods having the diameter and length of ∼180–240 nm and ∼1.5 μm, respectively, have been formed. The FESEM image also clearly showed that diameter and length of TiO2@ZnO NRAs are ∼250–320 nm and ∼1.5 μm, respectively. By using UV-VIS absorption spectra, the band gap of vertically aligned ZnO NRAs, TiO2@ZnO NRAs, and TiO2 NTAs have been calculated and its values were 3.14, 3.20, and 3.52 eV, respectively. The dye-sensitized solar cell was prepared by using three different working electrodes ZnO NRAs, TiO2@ZnO, and TiO2 NTAs. The power conversion efficiency of dye-sensitized solar cells prepared using ZnO NRAs, TiO2@ZnO, and TiO2 NTAs are 3.53%, 4.04%, and 5.18%, respectively. TiO2 NTAs with 10 s HCl etching exhibited the highest photoelectric conversion efficiency of 5.18% with short-circuit photocurrent density (Jsc) = 13.34 mA/cm2 and open-circuit photovoltage (Voc) = 0.63 V.

Nanoscopic insights into the effect of silicon on core-shell InGaN/GaN nanorods: Luminescence, composition, and structure

GaN-based nanorods and nanowires have recently shown great potential as a platform for future energy-efficient photonic and optoelectronic applications, such as light emitting diodes and nanolasers. Currently, the most industrially scalable method of growing III-nitride nanorods remains metal-organic vapour phase epitaxy: whilst this growth method is often used in conjunction with extrinsic metallic catalyst particles, these particles can introduce unwanted artifacts in the nanorods such as stacking faults. In this paper, we examine the catalyst-free growth of GaN/InGaN core-shell nanorods by metal-organic vapor phase epitaxy for optoelectronic applications using silane to enhance the vertical growth of the nanorods. We find that both the silane concentration and exposure time can greatly affect the nanorod properties, and that larger concentrations and longer exposure times can severely degrade the nanorod structure and thus result in reduced emission from the InGaN QW shell. Finally, we report that the mechanism behind the effect of silane on the nanorod structure is the unintentional formation of an SiNx interlayer following completion of the growth of the nanorod core. This interlayer induces the growth of GaN islands on the nanorod sidewalls, the spatial distribution of which can affect their subsequent coalescence during the lateral growth stages and result in non-uniformity in the nanorod structure. This suggests that careful control of the silane flow must be exerted during growth to achieve both high aspect ratio nanorods and uniform emission along the length of the nanorod.

Upconverting nanocomposites with combined photothermal and photodynamic effects.

Lanthanide-doped upconverting nanoparticles (UCNPs) have been studied for diverse biomedical applications due to their inherent ability to convert near-infrared (NIR) excitation light to higher energies (spanning the ultraviolet, visible, and NIR regions). To explore additional functionalities, rational combination with other optically active nanostructures may lead to the development of new multimodal nanoplatforms with theranostic (therapy and diagnostic) capabilities. Here, we develop a nanocomposite consisting of NaGdF4:Er3+, Yb3+ UCNPs, mesoporous silica (SiO2), gold nanorods (GNRs) and a photosensitizer, with integrated functionalities including luminescence imaging, photothermal generation, nanothermometry and photodynamic effects. Under 980 nm irradiation, GNRs and UCNPs are simultaneously excited due to the overlap between the surface plasmon resonance of the GNRs and the absorption of the UCNPs leading to plasmonic enhancement of the upconverted luminescence, while concomitantly creating a temperature gradient. The temperature increase can be determined from the intensity ratio of the upconverted green emission of the UCNPs. Finally, a photosensitizer, zinc phthalocyanine, was loaded into the mesoporous SiO2. Upon laser irradiation, the upconverted visible light subsequently activates the photosensitizer to release reactive oxygen species. The multifunctional GNR@SiO2@UCNPs nanocomposites showed strong luminescence signal when incubated in HeLa cervical cancer cells, making them ideal bioprobes for future theranostic applications.

Hexagonal WO3 Nanorods as Ambipolar Electrode Material in Asymmetric WO3//WO3/MnO2 Supercapacitor

Unique efficacy of hexagonal WO3 (h-WO3) nanorods (NRs) both as anode and cathode materials realized via a core-shell design for constructing an asymmetric supercapacitor (ASC) with compelling performances is demonstrated. The WO3/MnO2 core-shell NR cathode designed by combining ultra-thin MnO2 nano-flake shell with h-WO3 NR core shows ameliorated electrochemical performance in terms of areal capacitance and rate capability in relation to pristine MnO2 electrodes. The study also elucidates the high charge storage capacity of h-WO3 NRs anode with contributions arising both from redox pseudocapacitance and intercalation capacitance due to proton intercalation/deintercalation inside the intracrystalline tunnels in h-WO3. Accordingly, the WO3//WO3/MnO2 ASC exhibits stable capacitance within a potential window of 1.8 V in an aqueous electrolyte with a volumetric capacitance of 7.22 F/cm3 and an energy density of 3.25 mWh/cm3, characterizing it as one of the state-of-the-art ASCs in the present scenario. The use of versatile h-WO3 NRs in designing both the negative and positive electrodes could be critical in realizing next-generation high-performance supercapacitors.

CoO/CoFe2O4 bi-component nanorod core with S-doped carbon shell as excellent anode for lithium ion battery

In this work, a novel CoO/CoFe2O4 bi-component nanorod coated with S-doped carbon nanospheres shell (CO/CFO@SC Nr) composites have been synthesized through one in-situ polymerization and subsequent annealing treatment. The S-doped carbon shell, special structure and synergistic effect between CoO and CoFe2O4 significantly enhance the electrochemical performance of the CoO/CoFe2O4 anode material. CO/CFO@SC Nr composites present an impressive capacity of 511.3 mAh g−1 after 700 cycles when tested at a high current density of 2000 mA g−1. In addition, this is the first time that polythiophene is used as sulfur and carbon source to synthesis transition metal oxide (TMO) @S-doped carbon core-shell composites. This work illuminates a new preparation way for fabrication other TMO@S-doped carbon core-shell materials for lithium-ion batteries and other energy storage devices.

Heteroaggregation Approach for Depositing Magnetite Nanoparticles onto Silica-Overcoated Gold Nanorods

Hydrophobic, oleylamine-stabilized magnetite nanoparticles (Fe3O4 NPs) dispersed in hexanes can assemble into dense coatings on the surface of silica-overcoated gold nanorods (SiO2-GNRs) dispersed in ethanol by mixing. In this nonaqueous heteroaggregation process, Fe3O4 NPs are destabilized when ethanol is added, resulting in core/satellite Fe3O4-SiO2-GNRs within a few minutes. The composition of the solvent mixture allows tuning of the polarity and driving forces toward aggregation. At the optimal 2:1 volume ratio of hexanes:ethanol, heteroaggregation to form Fe3O4-SiO2-GNRs occurs quickly, while avoiding homoaggregation of Fe3O4 NPs or SiO2-GNRs. Fe3O4-SiO2-GNRs retain the longitudinal surface plasmon resonance of the gold nanorod cores and are magnetically responsive and separable. The Fe3O4 NPs remain bound on the surface of the Fe3O4-SiO2-GNRs during multiple cycles of magnetic extraction and redispersion. Oleylamine ligands on the Fe3O4 NPs render the Fe3O4-SiO2-GNRs dispersible in nonpolar solvents...

Structure-dependent performance of TiO2/C as anode material for Na-ion batteries

The performance of energy storage materials is highly dependent on their nanostructures. Herein, hierarchical rod-in-tube TiO2 with a uniform carbon coating is synthesized as the anode material for sodium-ion batteries by a facile solvothermal method. This unique structure consists of a tunable nanorod core, interstitial hollow spaces, and a functional nanotube shell assembled from two-dimensional nanosheets. By adjusting the types of solvents used and reaction time, the morphologies of TiO2/C composites can be tuned to nanoparticles, microrods, rod-in-tube structures, or microtubes. Among these materials, rod-in-tube TiO2 with a uniform carbon coating shows the highest electronic conductivity, specific surface area (336.4m2g−1), and porosity, and these factors lead to the best sodium storage capability. Benefiting from the unique structural features and improved electronic/ionic conductivity, the as-obtained rod-in-tube TiO2/C in coin cell tests exhibits a high discharge capacity of 277.5 and 153.9 mAh g−1 at 50 and 5000mAg−1, respectively, and almost 100% capacity retention over 14,000 cycles at 5000mAg−1. In operando high-energy X-ray diffraction further confirms the stable crystal structure of the rod-in-tube TiO2/C during Na+ insertion/extraction. This work highlights that nanostructure design is an effective strategy to achieve advanced energy storage materials.

Nanoantagonists with nanophase-segregated surfaces for improved cancer immunotherapy

The blockade of PD-1/PD-L1 interaction by peptide antagonists can unleash and enhance pre-existing anti-cancer immune responses of T cells to eradicate cancer cells. However, low proteolytic stability is the “Achilles' Heel” of peptides. Here, we first report a nanoantagonist with a physiological temperature sensitive nanophase-segregated surface that exhibits significantly enhanced blood circulation, peptide stability and PD-L1 immune checkpoint blockade efficacy. Thermosensitive polymers with different phase transition temperatures (Tt) are used to form the nanophase-segregated surface on an Au nanorod core. Importantly, the nanophase-segregated surface aids the nanoantagonist to resist protein adsorption and enhance the systemic stability of the linked peptides. Finally, the as-designed nanoantagonist effectively blocks PD-1/PD-L1 interaction in vitro and in vivo, enhances the pre-existing CD8+ T cell tumor destruction capability and inhibits tumor growth. This study offers a new strategy for designing nano-formulations for cancer immunotherapy.