Nanorod Structure Research Articles

CeO2-C nanorods obtained by high-temperature carbonization of Ce-MOF as separator coating for Li-S battery

Lithium-sulfur batteries (LSBs) are of great interest to researchers due to their high theoretical specific capacity and high energy density. Unfortunately, because of sulfur's weak conductivity and the shuttle effect of polysulfides, the application prospects of LSBs are facing great challenges. To suppress the shuttle effect of polysulfides, nanorod-like CeO2 and CeO2-C using Ce-MOF as the precursor was successfully prepared and applied to the separator of LSBs. Coating CeO2 and CeO2-C obtained by calcination in different atmospheres on PE separators can effectively enhance the electrochemical properties of LSBs due to the excellent chemisorption and catalytic effect of CeO2 on lithium polysulfides. In particular, CeO2-C which is obtained by calcination of Ce-MOF in N2 atmosphere has abundant micro and meso porous structures, which can quickly adsorb polysulfide in the electrolyte and accelerate the redox kinetics at the same time. Moreover, the nano-rod structure of CeO2 and CeO2-C also improves the conductivity of the separator. After a series of electrochemical tests, it was discovered that the discharge capacity of the CeO2-C coated separator battery on the first cycle was 1240 mA h g−1 when the cathode sulfur loading was approximately 2.5 mg cm−2, and that the discharge capacity remained 520 mA h g−1after 500 loops at 0.5 C. Even when the sulfur loading reaches 5.5 mg cm−2, it also has a good cyclic stability, demonstrating its application potential.

Multi-Effect Enhanced Raman Scattering Based on Au/ZnO Nanorods Structures.

Surface-enhanced Raman scattering (SERS) was considered a potential spectroscopic technique for applications of molecular detection and has drawn great research interest during the past decade. So far, fabrications of cost-effective SERS substrates with high sensitivity and stability and the corresponding enhanced mechanisms are always among the list of research topics, although great progress has been made. In this work, Au particles were decorated on Si, ZnO film and ZnO nanorod arrays simultaneously by an economical method of ion sputtering, generating three kinds of SERS substrates for R6G detection. The morphology difference of Au particles on different samples and the consequent influence on Raman scattering were studied. The experiment results exhibited that substrates with Au particles decorated on ZnO nanorods had the highest Raman enhancement factor. Furthermore, multi-effect enhanced mechanisms summarized as localized surface plasmon resonance (LSPR) filed coupling, electron transferring induced by LSPR of Au particles and whispering gallery mode (WGM) effect of the ZnO cavity were presented. This work provides a convenient and efficient method of fabricating SERS substrates and indicates that such proper metal/semiconductor composite structures are promising candidates for SERS applications.

Electrochemical synthesis of snowflake-like brass nanorod structures

Electrochemical synthesis of snowflake-like brass nanorod structures

Efficient cascade C-N coupling reactions catalyzed by a recyclable MoOx/Nb2O5 nanomaterial for valuable N-heterocycles synthesis

The efficient cascade synthesis of pharmaceutically valuable N-heterocycles at solvent-free conditions was achieved using a robust, recyclable MoOx/Nb2O5 nanocatalyst. The results of catalyst screening revealed that the MoOx/Nb2O5 nanorods, calcined at 500 °C (MoNb5), exhibit excellent catalytic activity in the oxidative coupling of benzylamine with 96.5% conversion and >99.6% selectivity to the desirable imine product. The uniform dispersion of Mo-oxide nanoparticles (average particle size: 5.2 ± 0.5 nm) on shape-controlled Nb2O5 nanorods (width: 5.3 ± 0.5 nm and length: 23–38 nm) in MoNb5 catalyst led to improved structural and acid properties, beneficial for the cascade C-N bond construction. The shape-controlled MoNb5 catalyst showed versatile activity in various cascade C-N coupling reactions to obtain 2-phenylbenzimidazole, 2-phenylquinaxoline, and 2-phenyl-2,3-dihydroquinazolin-4(1H)-one with good to excellent yields at solvent-free conditions. The optimum ratio of Lewis/Brønsted acid sites, the unique structure of Nb2O5 nanorods, and the strong MoO3-Nb2O5 interaction are the key reasons for the higher activity of MoNb5 catalyst. The efficient reusability of MoNb5 catalyst, its remarkable activity in diverse N-heterocycles synthesis, and efficient gram-scale synthesis emphasize its practical application for the cascade C-N coupling reactions under benign conditions.

Effect of the thickness on the photocatalytic and the photocurrent properties of ZnO films deposited by spray pyrolysis

In this work, we have investigated the structure, morphology, photoluminescence, photocatalytic and photocurrent properties of ZnO thin films as a function of their film thickness (tZnO) fabricated via ultrasonic spray pyrolysis technique. The X-Ray diffraction patterns exhibited the formation of polycrystalline wurtzite phase of ZnO. Scanning electron microscopy images showed the uniform morphology with nanorod structure. The photosensitivity and photocatalytic efficiency are found to be optimum at tZnO = 1200 nm and are attributed to the improved photogeneration of charge carriers and higher concentration of oxygen vacancies. A direct correlation is established between the photosensitivity and photodegradation process. The incident photon-to-electron conversion efficiency (IPCE) and photocatalytic efficiency for the ZnO film at tZnO = 1200 nm are estimated to be 31.5% and 100% respectively. The obtained result suggests that ZnO thin films are potential candidates for applications in various optoelectronic devices.

Preparation of TiN nanorods for SERS substrate by controlling pulse frequency of high power impulse magnetron sputtering

The surface-enhanced Raman scattering (SERS) substrate was fabricated using titanium nitride nanorods structures (TiN NRs) which were prepared by the combination of high-power impulse magnetron sputtering (HiPIMS) and glancing angle depositions (GLAD) techniques. The surface morphology, crystalline structures and chemical composition of TiN NRs were characterized by field-emission scanning electron microscopy (FE-SEM), grazing incidence X-ray diffraction (GIXRD) and X-ray photoelectron spectroscopy, (XPS) respectively. Additionally, a portable Raman spectroscopy at 532 nm was used to inspect the performance of Raman signal enhancement. The cubic phase of TiN NRs was shown on (111), (200) and (220) planes. The efficiency of the generated Raman signal of Rhodamine 6 G be measured at a detection limit of 10–6 M with a long shelf-life of TiN NR SERS of more than 28 days. According to the experimental results, TiN NRs are a promising candidate for SERS substrates fabricated cost effectively.

Investigation of Intensity Dependent Nonlinear Absorption in Cerium Phosphate Nanorods

Cerium Phosphate (CePO4) is a material that has attracted attention because of its unique properties, redox capabilities, and a wide variety of applications. Cerium Phosphate nanoparticles with a nanorod structure were successfully synthesized by a hydrothermal synthesis procedure using Cerium Nitrate Hexahydrate (Ce (NO3)3.6H2O) and Diammonium Hydrogen Phosphate ((NH4)2HPO4) as the precursors without adding any surfactants. The synthesized CePO4 nanorods were characterized using X-ray Powder Diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis which showed pure monoclinic nanorod structures. The linear absorption was analyzed by UV-visible absorption spectrometry. The nonlinear absorption was measured by the open aperture Z-scan technique using a Q switched Nd-YAG laser at 532nm. The Z-scan curve exhibited reverse saturable absorption. In this study, the dependence of nonlinear absorption of CePO4 on the intensity of incident light was investigated. The non-linear absorption coefficient was measured and it was found that the non-linear absorption decreased with the increasing intensity.

001]-oriented LiMn0.6Fe0.4PO4/C nanorod microspheres contributing high-rate performance to olivine-structured cathode for lithium-ion battery

Recently, cathode materials for Li-ion batteries (LIBs) with high-voltage platforms have become a research hotspot. Olivine-structured LiMnPO4 has the advantage of 4.1 V voltage platform but also has been plagued by poor e-/Li+ conductivity. Here, we report a facile synthetic strategy to fabricate LiMn0.6Fe0.4PO4/C (LMFP) composite. Such composite is composed of [001]-oriented nanorods and assembled into dense microspheres. The [001]-oriented nanorod structure exhibits a shortened Li+ diffusion length resulting from a smaller dimensional size in the [010] direction. Meanwhile, the conductive carbon nanolayer is uniformly coated on the surface of LiMn0.6Fe0.4PO4 nanorods, which greatly improves the e- conductivity of the material. The [001]-oriented structure feature combined with improved e- conductivity contributes to the delivery of extraordinary rate capabilities (141.6 mAh/g at 10C) and remarkable cycling stabilities (97.8% retention rate after 300 cycles at 1C). Such rational-designed nanorod microspheres are good candidates for the next generation of olivine-structured cathode for high-rate, high-energy, and high-safety LIBs.

Coral-like Sb2Se3/SnS2 photocathode co-optimized by bilayer Sb2Se3 structure and hole-storage layer for photoelectrochemical water splitting

Achieving high light absorption efficiency and low photogenerated carrier recombination rates is critical in the production of H 2 by photoelectrochemical water splitting. Antimony selenide (Sb 2 Se 3 ) has recently received much attention due to its favorable optoelectronic properties, low cost and unique nanorod structure. Herein, we constructed coral-like Sb 2 Se 3 /SnS 2 heterojunction by introducing SnS 2 with a nanosheet structure, which contributes to enhanced light absorption and provides more reaction sites. On this basis, synergistic optimization is carried out by the bilayer Sb 2 Se 3 structure and ferrihydrite (Fh) to effectively inhibit charge recombination at the interface and facilitate electron transport. Compared to monolayer Sb 2 Se 3 (1.54%), the IPCE value of bilayer Sb 2 Se 3 /SnS 2 /Fh can reach 20.56% (735 nm). The prepared bilayer Sb 2 Se 3 /SnS 2 /Fh has a maximum photocurrent density of approximately − 1.0 mA cm −2 at 0 V RHE , continuous testing for 1 h compared to monolayer Sb 2 Se 3 still maintains more than 4 times improvement. This work provides a basis for the development of high efficiency and low cost Sb 2 Se 3 -based optoelectronic devices. • The bilayer Sb 2 Se 3 structure was constructed by sequential deposition. • A combination between 1D Sb 2 Se 3 nanorods and 2D SnS 2 nanosheets has been achieved. • Surface modification using ferrihydrite as an interface engineering material. • Optimized photoelectrode current density is 50 times higher than original sample. • The PEC mechanism of bilayer Sb 2 Se 3 /SnS 2 /Fh photoelectrode was proposed.

Growth and Structure of Single-Crystal ZnO Nanorods Codoped with Fe and Li for Multiferroic Applications

Growth and Structure of Single-Crystal ZnO Nanorods Codoped with Fe and Li for Multiferroic Applications

Study on the absorption characteristics and refractive index sensitivity characteristics of the periodic structure of double nanorods

Metamaterial perfect absorber is very important in the study of refractive index sensor. The time domain finite difference method is used to simulate the surface plasmon structure. The double nanorod periodic structure is designed, and the parameters of the top layer structure are optimized according to the impedance matching principle, and the absorption rate of the structure to the light wave reaches 99.6% when the wavelength is about 12 mm. The absorption spectroscopy of the structure is studied with the change of the refractive index of the spatial medium around the structure, and the sensitivity of the double nanorod structure is 4,008 nm/RIU, which can be used to measure the refractive index of the gas.

ZnO nanorods loading with fatty amine as composite PCMs device for efficient light-to-thermal and electro-to-thermal conversion

Phase change materials (PCMs) with ideal light-to-thermal conversion efficiency play an important role in solar energy storage and conversion. Hence, we report the fabrication of a novel composite PCMs (CPCMs) device based on ZnO nanorods deposited indium tin oxide (ITO) glass loading with fatty amines. ZnO nanorods were deposited on the ITO glass using a three-electrode electrodeposition method, and 1-Hexadecylamine (HDA) was loaded on the ITO glass via spin-coating, followed by spraying polypyrrole (ppy) on the surface of CPCM device to improve thermal conductivity and solar absorption. The as-prepared CPCM device exhibits excellent light-to-thermal conversion efficiency, achieving a high conversion efficiency of 90.2% obtained at 1sun owing to its high light absorption (80%), enhanced thermal conductivity (improved by 57.8%), and the unique vertical aligned nanorods structure which could significantly decrease tortuosity, thereby reducing thermal route and lowering thermal response time. Furthermore, the electro-to-thermal conversion efficiency of the CPCMs device has also been investigated and the results show that it can reach up to 69.8% under a low voltage of 5 V, indicating that the CPCM device has a high potential in the field of electro-to-thermal conversion. Based on the benefits listed above, the CPCM device may serve an ideal platform for a wide range of solar energy storage and conversion applications.

Enhancement of the catalytic performance for CH3OH oxidation of nanoporous Pt by the addition of Cu and Ce to precursors

Melt-spun Al-Pt-Cu-Ce ribbons were chosen to prepare a nanoporous composite formed by thinner Pt ligaments with loaded CeO2. Dealloying the ribbons in 20 wt% NaOH prior to a calcination at 500 °C, allowed us to achieve nanoporous structures consisting of Pt/CuO ligaments. During the first synthetic step, Pt-Cu unlimited solid solution was obtained calcination yielded a microstructure composed by Pt nanoparticles embedded in a CuO matrix, creating highly narrow Pt nanopores. To remove the CuO matrix, a second corrosion treatment (50 wt% NaOH) was carried out, producing a microstructure in which CeO2 nanorods were blended with Pt ligaments. These samples had a large specific area of 116.75 m2·g−1 with 0.301 cm3·g−1 of pore volume. The highest peak current density for CH3OH oxidation (1310 mA·mg−1Pt) was obtained for the dealloyed Al81.5Pt8Cu10Ce0.5 ribbons. The peak current density ratio between the forward (If) and the backward scan (Ib) of the dealloyed Al-Pt-Cu-Ce increased up to 7.4, indicating excellent poison tolerance. The unique composite structure of CeO2 nanorods embedded with Pt ligaments led to a strong interaction between CeO2 and Pt. As a result, the composite exhibited better poison tolerance with enhanced catalytic activity.

Refining the surface properties of WO2.7 by vacancy engineering and transition metals doping for enhanced alkaline hydrogen evolution reaction

Anion-exchange membrane water electrolyzer is a promising and green technology for hydrogen production. However, the high energy barriers for the water dissociation step for breaking the strong HOH covalent bond results in sluggish hydrogen evolution reaction (HER) kinetics at the cathode. Herein, we present a strategy to optimize the morphology and surface properties of WO2.7 by introducing oxygen vacancies and doping with various transition metals. The experimental analysis demonstrates that the developed Co-WO2.7-x and Ni-WO2.7-x with ultrafine nanorods structure provide a larger electrochemical surface area than the other synthesized catalysts. Furthermore, theoretical analysis reveals that Co-WO2.7-x has the lowest energy barrier (0.65 eV) for the water dissociation step, which is much lower than that of WO2.7 (2.61 eV). Consequently, the Co-WO2.7-x delivers a current of 10 mA cm−2 at a small overpotential of 59 mV for alkaline HER.

Photocathodic protection of amorphous and nanorod zinc oxide thin-film coatings on stainless steel AISI 304 fabricated by spray pyrolysis and hydrothermal technique

The photoelectrochemical cathodic characteristics of amorphous and nanorod ZnO thin-film coatings on stainless steel AISI 304 (SS304) substrates were investigated. An amorphous ZnO thin film was coated on a SS304 substrate at 200 °C using the spray pyrolysis technique. A nanorod ZnO thin film was coated on a SS304 substrate by spraying seed layers at 400 °C and growing the nanorod structures with a hydrothermal process. The results from x-ray diffractometry and energy dispersive x-ray spectroscopy confirmed amorphous and nanorod ZnO coatings. The ZnO-coated SS304 samples were subjected to the potentiostatic polarization testing under dark and UV conditions, with the ZnO-coated sides of SS304 immersed in a 0.1 M Na2S + 0.2 M NaOH solution and the opposite bare sides in a 3 wt% NaCl solution. For both amorphous and nanorod ZnO coatings, the current densities (icorr) were increased while the voltages (Vcorr) were decreased with the UV light exposure. The photoelecrochemical cathodic mechanism has been explained with the photogenerated electron-hole pairs in ZnO, the hole consumption by the S/S−2 redox reaction, and the electron transfer to SS304. The microstructure analyses showed that the pitted areas resulting from the polarization test under UV light were clearly smaller than those from the polarization test under dark condition.

Nano-sized cerium vanadium oxide as corrosion inhibitor: A microstructural and release study

• A simple chemical route to synthesize cerium vanadate. • Mixed nanostructure. • Cerium vanadate is an effective corrosion inhibitor for ferrous alloys. • It forms a layer on the steel surface. • Self-healing and smart corrosion inhibitor. The synthesized, nano-sized cerium vanadate is proposed as a self-healing corrosion inhibitor for ferrous alloys (e.g., automotive high strength steel (HSS) and mild steel (MS)). Cerium vanadate prepared at two different pH conditions (neutral and basic) showed similar corn-like morphology with nanorod structure. UV-Vis spectroscopy studies revealed that the release rate of cerium vanadate-B (basic condition) was higher than cerium vanadate-N (neutral condition) in 0.1 M NaCl solution. The specimen exposed to 0.1 M NaCl containing a supersaturated solution of cerium vanadate-B (1000 ppm) revealed 8 times and 6 times lower corrosion current density values for HSS and MS respectively than that of the one without corrosion inhibitor. There was a gradual increase in the film resistance ( R film ) on both HSS and MS observed as a function of exposure time in corrosive medium containing cerium vanadate-B inhibitor. An order higher impedance values were observed for both HSS and MS immersed for 168 h, highlighting the self-healing effect of the cerium vanadate compound. The X-ray photoelectron spectroscopy results showed the presence of multivalent oxidation states of both cerium and vanadium species. The inhibiting action is attributed to the high solubility of cerium vanadate in the corrosive medium to form a film on the metal surface. The dissolution/solubility of the corrosion inhibitor was more favorable in neutral to alkaline conditions than in acidic conditions.

Direct Z-scheme mediated SmVO4/UiO-66-NH2 heterojunction nanocomposite for the degradation of antibiotic tetracycline hydrochloride molecules under sunlight.

The use of tetracycline hydrochloride (TCH) for veterinary, human therapy, and agriculture has risen in the past few decades, making it to become one of the most exploited antibiotics. However, TCH residue in the environment is causing issues related to the evolution of antibiotic-resistant bacteria. To address such a problem, photodegradation offers a potential solution to decompose these pollutants in wastewater and thereby mitigates negative environmental impacts. In this context, the research focuses on the use of the rare-earth metal oxide samarium orthovanadate (SmVO4) with nanorod structure, coupled with UiO-66-NH2 for the photocatalytic degradation. Their photocatalytic activity to degrade antibiotic TCH molecules is explored under simulated solar light irradiation. The integration of UiO-66-NH2 with SmVO4 enhanced the light absorption, recombination resistance, carrier lifetime (from 0.382 to 0.411ns) and specific surface area (from 67.17 to 246m2/g) of the composite system as confirmed from multiple analyses. The obtained results further indicated that SmVO4/UiO-66-NH2 nanocomposites could form a direct Z-scheme based heterojunction. Such mechanism of charge transfer leads to the effective degradation of TCH molecules up to 50% in 90min under solar light, while it is degraded only 30% in the case of bare-SmVO4 nanorods. In this work, the incorporation of UiO-66-NH2 positively influences photoelectrochemical properties and improves the overall photoredox properties of SmVO4 for the degradation of complex compounds like antibiotic TCH molecules. Therefore, UiO-66-NH2 can be proposed as an effective material to sensitize the rare-earth based photocatalytic material.

Synthesis of hierarchically porous Ni foam-supported heazlewoodite Ni3S2 nanorod electrocatalysts for highly efficient oxygen evolution reaction

At present, the design of highly efficient and stable oxygen electrocatalysts for water-splitting cells in alkaline medium is predominantly limited by the sluggish kinetics for the oxygen evolution reaction (OER). This study proposes a facile and reproducible synthesis process to nurture the hierarchically porous Ni3S2 arrays on nickel foam (Ni3S2@NF) for use as a catalyst. For the hydrothermal synthesis reaction, ultrathin nanorod heazlewoodite Ni3S2 catalysts on NF is synthesized by controlling the amount of hydrazine (2 mL) and the processing time/temperatures (150 ℃ for 12 h). Due to the hierarchically porous nanorod morphologies, Ni3S2@NF under O2-saturated 1 M KOH aqueous solution shows excellent OER performance, with a low overpotential of 263 mV at a current density of 100 mA‧cm−2 and a Tafel slope of 72 mV‧dec−1. Further, Ni3S2@NF shows stable potential behavior at around 1.521 V under the constant current operation of 50 mA cm−2 for 50 h. Ni3S2@NF also shows negligible performance degradation during the constant current (at 50 mA cm−2 for 50 h) and voltage cycling (1.25–1.65 V for 1000 cycles) tests in a 1 M KOH solution. The excellent catalytic performance of Ni3S2@NF can be attributed to the hierarchically porous and ultrathin nanorod structures, the multi-valence-state character of Ni element, and the synergistic effect of NF, and high intrinsic catalytic active electrocatalysts for the OER.

Uniaxial Strain Engineering via Core Position Control in CdSe/CdS Core/Shell Nanorods and Their Optical Response.

Anisotropic strain engineering has emerged as a powerful strategy for enhancing the optoelectronic performance of semiconductor nanocrystals. Here, we show that CdSe/CdS dot-in-rod structures offer a platform for fine-tuning the optical response of CdSe quantum dots through anisotropic strain. By controlling the spatial position of the CdSe core within a growing CdS nanorod shell, varying degrees of uniaxial strain can be introduced. Placing CdSe cores at the end of the CdS nanorod induces strong asymmetric compression along the c-axis of the wurtzite CdSe core, dramatically altering its absorption and emission characteristics, whereas CdSe cores located near the middle of the nanorod experience a comparatively weak uniaxial strain field. The change in absorption and emission spectra and dynamics for highly strained end-position CdSe/CdS nanorods is explained by (1) relative shifting of the valence band light hole and heavy hole levels and (2) introduction of a strong piezoelectric potential, which spatially separates the electron and hole wave functions. The ability to tune the degree of uniaxial strain through core position control in a nanorod structure creates opportunities for precisely modulating the electronic properties of CdSe nanocrystals while simultaneously taking advantage of dielectric and optical anisotropies intrinsic to 1D nanostructures.

Ethynyl and Furyl Functionalized Porphyrin Complexes as New Organic Cathodes Enabling High Power Density and Long-Term Cycling Stability.

Organic cathode materials have recently attracted abundant attention due to their flexible structural tunability and recyclability. However, the low intrinsic electrical conductivity and high solubility in electrolytes of organic electrode materials have significantly limited their practical application. Herein, we present [5,15-bis(ethynyl)-10,20-difurylporphinato] copper(II) (CuDEOP) as a new cathode for rechargeable organic lithium batteries (ROLBs). The combination of both ethynyl and furyl groups of the CuDEOP cathode with a nanorod structure renders it with enhanced structural stability and an extended delocalized π-electron system to deliver excellent cycling stability (capacity retention of 76% after 6000 cycles) and a high power density (16 kW kg-1). The furyl electroactive groups participate in charge storage contribution to achieve a reversible six-electron-transfer redox reaction in a specific voltage range. The mechanism characterizations indicate that the nitrogen atoms on the porphyrin ring act as active sites to alternatively store both PF6- anions and Li+ cations, and the charge storage process is a pseudocapacitive-dominated reaction. This observation will offer a new avenue for designing functionalized molecules for electrochemical energy-storage (EES) systems.