Uniform Nanorods Research Articles

Hydrothermal growth of Zn2GeO4 nanorods for optical and (Photo)Catalytic applications: An experimental and theoretical study

From the material design perspective, we reported a systematic investigation based on theoretical and experimental approaches to explore the physical properties of Zn2GeO4 nanorods prepared by hydrothermal method with different zinc precursors for optical and (photo)catalytic applications. All ZGO samples exhibited uniform nanorod morphology with high purity and crystallinity. A negative zeta potential ranging from −13 mV to −16 mV have been observed for these nanorods. Bandgap values indicated variations among samples synthesized with different precursors. The photoluminescence and photocatalytic activities for these nanorods, have been attributed to the presence of oxygen vacancies on the Zn2GeO4 surfaces. Experimental evidence suggests that these surface defects favor the formation of hydroxyl radicals identified as primary reactive oxygen species responsible for the methylene blue photodegradation. Toxicity testing of photocatalytic residues showed minimal phytotoxic effect on lettuce seed (Lactuca sativa) germination. Additionally, Zn2GeO4 was utilized as an acid catalyst for synthesizing isoxazol-5(4H)-ones, resulting in an increase in the yield from 69 % to 92 % by using this catalyst in multicomponent reactions. Lastly, the theoretical efforts outlined in the study aim to enhance the comprehension of the material design with well-defined morphology using realist theoretical models for the Zn2GeO4 nanorods for the first time.

The interaction of light with oxygen-vacancy-rich W18O49 nanoparticles synthesized using different acid molarities for acidic and neutral water treatments

Toxic industrial compounds as a global difficulty can adversely impact people's health and the environment which motivates studies on the interaction of light and metal oxide nanoparticles to treat the water through adsorption or photocatalysis mechanism by nanoparticles. In the paper, oxygen-vacancy-rich W18O49 nanorods are successfully synthesized by a facile one-pot hydrothermal method using different molarities of hydrochloric acid (HCl) (2–12 M) as proposed candidates to treat the wastewater and solve the global difficulty related to treating the acidic water. The results declare that the change in acid molarity leads to noteworthy changes in the characteristic properties of the produced W18O49 nanorods, and the lowest acid molarity (2 M) causes the formation of uniform and pure monoclinic W18O49 nanorods with the high specific surface area (SSA) of 51.33 m2/g. Furthermore, the nanorods exhibit indirect and direct band gap energies in the range of 2.52–2.68 eV and 2.54–3.08 eV, respectively, as influenced by varying acid molarities (2–12 M). Furthermore, the impressive effects of acid molarity on the methylene blue removal efficiency of the nanorods under ultraviolet (UV) light are observed. The highest efficiency is obtained for W18O49 nanorods synthesized using the acid molarity of 2 M which can be explained by its high SSA, small band gap energy, generation of a large number of electron-hole pairs, and its efficient charge separation. The efficiencies of water treatment reach up to 99 % and 99.5 % at pH of 7 and 5, respectively, which is an excellent achievement and leads to proposing the mentioned W18O49 nanorods as an excellent candidate for treating wastewater and acid factory effluent which represents an appreciable breakthrough in addressing the issue.

Localized surface plasmon-enhanced nanorod micro-LEDs with Ag nanoparticles embedded in insulating and planarizing spin-on glass

To enhance the emission of GaN-based Micro-LEDs (μLEDs), we etched uniform nanorods (NRs) on the μLED surface and filled the nanorod gaps with spin-on glass (SOG) containing mixed Ag nanoparticles (NPs). The nanorod structure creates a conducive environment for close interaction between Ag NPs and quantum wells (QWs), facilitating the coupling of Ag NPs as localized surface plasmons (LSPs) with the QWs to enhance light emission. The SOG acts as an insulating layer between Ag NPs and NRs, preventing electron leakage, while also serving as a planarization material for the nanorod structure. This configuration allows for the fabrication of a planar Indium Tin Oxide layer without short-circuiting the nanorod structure. Compared to traditional planar Micro-LEDs, NR-μLEDs with SOG-encased Ag NPs exhibit a 50% increase in electroluminescence (EL) intensity and a 56% increase in photoluminescence (PL) intensity. This work paves the way for broader applications of LSP in μLEDs.

Bimetal−organic framework-integrated electrochemical sensor for on-chip detection of H2S and H2O2 in cancer tissues

Studies on the interaction between hydrogen sulfide (H2S) and hydrogen peroxide (H2O2) in redox signaling motivate the development of a sensitive sensing platform for their discriminatory and dynamic detection. Herein, we present a fully integrated microfluidic on-chip electrochemical sensor for the online and simultaneous monitoring of H2S and H2O2 secreted by different biological samples. The sensor utilizes a cicada-wing-like RuCu bimetal−organic framework with uniform nanorods architecture that grows on a flexible carbon fiber microelectrode. Owing to the optimized electronic structural merits and satisfactory electrocatalytic properties, the resultant microelectrode shows remarkable electrochemical sensing performance for sensitive and selective detection of H2S and H2O2 at the same time. The result exhibits low detection limits of 0.5 μM for H2S and 0.1 μM for H2O2, with high sensitivities of 61.93 μA cm−2 mM−1 for H2S, and 75.96 μA cm−2 mM−1 for H2O2. The integration of this biocompatible microelectrode into a custom wireless microfluidic chip enables the construction of a miniature intelligent system for in situ monitoring of H2S and H2O2 released from different living cells to differentiate between cancerous and normal cells. When applied for real-time tracking of H2S and H2O2 secreted by colorectal cancer tissues, it allows the evaluation of their chemotherapeutic efficacy. These findings hold paramount implications for disease diagnosis and therapy.

MnCo2O4 Spinel Nanorods for Highly Sensitive Electrochemical Detection of Nitrite.

The rational design of nitrite sensors has attracted significant research interest due to their widespread use and the associated risks of methemoglobinemia and carcinogenicity. The undisclosed nitrite-sensing performance of the spinel cobaltite MnCo2O4 (MCO) prepared by an oxalate-assisted coprecipitation method is reported in this study. Spectroscopy and microscopy investigations revealed the formation of uniform MCO nanorods with a high aspect ratio. The electrocatalytic nitrite oxidation at the MCO-coated glassy carbon electrode (MCO/GCE) indicated the promising performance of the synthesized material for nitrite sensing. MCO/GCE detects nitrite in a concentration range of 5 μM to 3 mM and has a limit of detection of 0.95 μM with a higher sensitivity of 857 μA mM-1 cm-2 in a response time of 4 s. In MCO, the mixed-valence states of Co2+/Co3+ confer a high electrical conductivity, and higher valent redox couples of Mn and Co impart remarkable electrocatalytic activity toward nitrite oxidation. MCO spinel undergoes facile and ultrafast faradaic reactions to mediate nitrite oxidation. Additionally, the mesopores of MCO nanorods facilitate the rapid diffusion of electrolyte and nitrite ions. Employing the electrode in sensing nitrite in milk, lake, and tap water samples further validates its potential application in real-life testing. MCO spinel nanorods showcase promising scope for utilization in the electrochemical sensing of nitrite and inspire further exploration of transition-metal oxide-based mixed-spinel materials.

An Exploration of Cysteamine as a Subphase Additive for the Fabrication of Uniform Gold Nanorod Arrays using Langmuir-Blodgett Deposition.

Gold nanorods (AuNRs) have attracted significant attention over the past several decades for a variety of applications and there has been steady progress with regards to their synthesis and modification. Despite these advances, the assembly of AuNRs into well-organized hierarchical assemblies remains a formidable challenge. Specifically, there is a need for tools that can fabricate assemblies of nanorods over large length scales at low cost with the potential for high-throughput manufacturing. Langmuir-Blodgettry is a monolayer deposition technique which has been primarily applied to amphiphilic molecules, but which has recently shown promise for the ordering of functionalized nanoparticles residing at the air-water interface. In this work, Langmuir-Blodgett deposition is explored for the formation of AuNR arrays for enhanced surface-enhanced Raman spectroscopy (SERS) sensing. In particular, both surface modification of the AuNRs as well as subphase modification with cysteamine were evaluated for AuNR array fabrication.

High Color Conversion Efficiency Realized in Graphene‐Connected Nanorod Micro‐LEDs Using Hybrid Ag Nanoparticles and Quantum Dots

AbstractIn this paper, a uniform nanorod (NR) array is etched onto the surface of Micro‐Light‐Emitting‐Diodes (µLEDs) and mix Ag nanoparticles (NPs) with QDs to fill the gaps between the nanorods. Simultaneously, the study utilizes graphene to connect individual nanorods and enhance current spreading. The nanorod array's structure significantly reduces the distance between the QDs and the quantum well (QW), reducing energy loss from the excitation light source through a non‐radiative energy transfer (NRET) mechanism. Additionally, the Ag NPs function as localized surface plasmons (LSPs), further enhancing the CCE of QDs via the absorption resonance. In this study, the effects of two types of Ag NPs are compared with different absorption resonance peaks on device performance. The results demonstrate that Ag NPs with absorption resonance peaks matching the emission wavelength of QDs play a more crucial role in the system. This configuration achieves a CCE of 77.78% for µLEDs with nanorod arrays, operating at a current of 10 mA. Compared to the conventional µLED structure with QDs only on the surface, the proposed method improves the CCE of µLEDs by an impressive 86.5%. This outcome underscores the significant contribution of the NR structure and LSPs in enhancing the CCE of QD‐µLEDs.

Investigating the Dielectric Photosensitivity of Zinc Oxide Nanostructures Under Ultraviolet Light

In this study, we prepared a ZnO thin film using the sol-gel spin-coating method on glass substrates. We repeated the synthesis procedure once, twice and four times to obtain the samples. We then investigated the FESEM images, XRD diffractograms, Hall effect and dielectric measurement of the samples. We observed the phase transition from the wurtzite to the zinc blende phase as a result of the number of repetitions. The films exhibited direct band gaps ranging from 3.2 eV to 3.3 eV. This result indicate that the two-times synthesis process has considerably affected the morphology and also improved the crystallinity of the layer. The sample of which the surface was covered with nearly uniform short nanorod grains with an average diameter of ~ 180 nm showed the highest sensitivity to ultraviolet light.

V2O5:Cu thin films-based device fabrication for high-performance photosensing application

The Cu doped V2O5 thin film were prepared by varying the doping concentration from 0, 1, 2, 3, 4 and 5 wt % through cost effective nebulizer spray pyrolysis method. The structural, optical, surface morphology of the samples were carried out by XRD, UV–Visible spectroscopy, FESEM studies. The XRD studies confirmed the orthorhombic structure of the sample and the crystallite size changes from 31 to 44 nm for the undoped to 3 % Cu doped V2O5 thin film. FESEM studies were employed to understand the surface morphology of the thin films and uniform nanorods were observed from this study. The optical bandgap of the samples was determined and 3 % Cu doped V2O5 thin film exhibited lower value of 2.21 eV. The photoluminescent peaks occur at 480, 530 and 575 nm due to the defects present in the samples. The photosensing behaviour of the prepared samples were done and found that the essential photosensing properties such as responsivity (R), detectivity (D*) and external quantum efficiency (EQE) for the V2O5:Cu3 % sample were 4.92 × 10−1 AW−1, 1.06 × 1011 Jones and 159 % respectively which proved that the 3 % Cu doped V2O5 thin film would be a most preferential material for the low cost photodetector.

The Effect of the Solution Flow and Electrical Field on the Homogeneity of Large-Scale Electrodeposited ZnO Nanorods.

In this paper, we demonstrate the significant impact of the solution flow and electrical field on the homogeneity of large-scale ZnO nanorod electrodeposition from an aqueous solution containing zinc nitrate and ammonium nitrate, primarily based on the X-ray fluorescence results. The homogeneity can be enhanced by adjusting the counter electrode size and solution flow rate. We have successfully produced relatively uniform nanorod arrays on an 8 × 10 cm2 i-ZnO-coated fluorine-doped tin oxide (FTO) substrate using a compact counter electrode and a vertical stirring setup. The as-grown nanorods exhibit similar surface morphologies and dominant, intense, almost uniform near-band-edge emissions in different regions of the sample. Additionally, the surface reflectance is significantly reduced after depositing the ZnO nanorods, achieving a moth-eye effect through subwavelength structuring. This effect of the nanorod array structure indicates that it can improve the utilization efficiency of light reception or emission in various optoelectronic devices and products. The large-scale preparation of ZnO nanorods is more practical to apply and has an extremely broad application value. Based on the research results, it is feasible to prepare large-scale ZnO nanorods suitable for antireflective coatings and commercial applications by optimizing the electrodeposition conditions.

Visible-light‑sensitive AgCu nanocomposites for sustainable inactivation of virus

The coronavirus disease 2019 (COVID-19) caused a large number of deaths and serious economic losses. Safety precautions and effective measures are urgently demanded to control the virus spread in public places. Owing to the longevity of the viruses in the aerosols and surfaces, sustained nanomaterials with efficient antiviral abilities during both daytime and night appear to be a promising way to control virus spread. Here, AgCu nanocomposites, which are outstanding antibacterial and antiviral elements, including Ag2Cu2O3 and AgCuO2, have been successfully prepared via a simple co-precipitation method for inactivation of model Qbeta (Qβ) bacteriophage. Notably, Ag2Cu2O3 has uniform nanorods morphology with a width of 50–100 nm and a length of 200–500 nm, regular elemental states of Cu2+ and Ag+, and good visible light response. Instead, AgCuO2 has more complex elemental states of Cu2+, Ag+, and Ag3+, including morphology with large particles of 500–1000 nm surrounded by small nanorods and nanoplates. Density functional theory (DFT) calculations showed that Ag2Cu2O3 has a lower work function than AgCuO2, indicating the charges can be better released from the surface. The accumulated surface charge can bind to the virus to inactivate it. As a result, Ag2Cu2O3 shows outstanding antiviral properties with a 6-log reduction (99.9999 %) of Qβ phage after 45 min contact under dark condition, and the activity can be further promoted to 7.5-log inactivation of Qβ phage after the same time contact under visible light irradiation, revealing its potential to sustainably prevent viruses spread in indoor environments.

Revisiting the Role of Seed Size for the Synthesis of Highly Uniform Sub-10 nm Length Gold Nanorods

Revisiting the Role of Seed Size for the Synthesis of Highly Uniform Sub-10 nm Length Gold Nanorods

In-situ co-precipitation of Bi-MOF derivatives for highly sensitive electrochemical glucose sensing

Bimetallic organic frameworks (Bi-MOFs) have been recognized as one of the hotpots for electrochemical sensing due to their high surface area, abundant active sites, tunable structures and porosity. However, inadequate conductivity and hidden active site of MOFs remain as great challenges, hindered its further development. Here, an in-situ co-precipitation strategy was proposed for preparing sophisticated hierarchical Bi-MOF derivatives with excellent glucose sensing. Firstly, uniform CuO nanorods as the precursor are synthesized in situ on a Carbon Cloth (CC). Subsequently, Cu-BTC and Co-BTC were co-precipitated on the precursor, while the significant effect of incremental Co2+ doping concentration was investigated. Finally, Cu/Co-MOF derivatives are successfully obtained by controlled thermal structural transformation. Due to the synergistic effect of bimetallic oxides and the exposed active sites, the prepared sensing electrode exhibits high sensitivity (4.93 mA mM−1 cm−2), fast response time (2.9 s), and outstanding long-term stability (30 days). This study proposes a practical method for in-situ synthesizing hierarchical Bi-MOF derivatives, which provides wide-ranging prospects in the field of electrochemical sensing.

Rare earth ion-infused α-MnO2 nano-rods for excellent EMI shielding efficiency: Experimental and theoretical insights

In this communication, for the first time rare earth elements like Gd3+ and Er3+ ions are impregnated into the α-MnO2tunneled structure involving the modified chemical synthesis route followed by hydrothermal technique. X-ray diffraction patterns and Raman spectroscopy confirm the proper phase formation without any impurity. A theoretical in-depth DFT study for the electronic bands and variation of density of states with the infusion of rare earth elements into the host structure confirms the experimental findings and depicts the suitability of the material for the EMI shielding application. The novel synthesis technique helps to achieve uniform nanorod formation with a high specific surface area. Doping-induced defects, high surface-to-volume ratio, Maxwell-Wagner–Siller interfacial polarization, etc. lead to achieving high dielectric response with moderate tangent loss at a frequency range of 40 Hz to 1 MHz. Temperature-dependent dielectric behavior indicates the paramagnetic to ferromagnetic transition at 120 °C and 70 °C for the Gd- and Er-doped α-MnO2 samples respectively. The electromagnetic interference (EMI) shielding effectiveness (SE) has achieved a maximum of −43 dB at 15.3 GHz and − 46 dB at 15.3 GHz for Gd- and Er-doped α-MnO2 thin layer of thickness ∼600 μm respectively. Higher dipolar polarization, loss tangent, conductive pathways, and defects inside the crystal lead to attaining a high EMI shielding efficiency. This result reveals >99.997% EMI SE against the hazardous electromagnetic waves in the microwave/GHz frequency region.

Insight into role of surface Sr‐sites in Sr/LOC‐HL catalyst for promoting low‐temperature oxidative coupling of methane

AbstractA series of Sr‐modified hedgehog‐like La2O2CO3 (Sr/LOC‐HL) catalysts were synthesized by the two‐step methods of coordination polymer induced formation and incipient wetness impregnation. Sr/LOC‐HL catalysts show the uniform nanorod morphology with width of 180 nm. The strong interaction between SrOx species and La2O2CO3 boosts the formation of active oxygen species for enhancing CH4 activation at low temperature. Sr/LOC‐HL catalysts show excellent catalytic performances for oxidative coupling of methane into C2+ hydrocarbons at low temperature (<500°C), and the selectivity is strongly dependent on the strong surface basic sites induced by the SrOLa bond. The Sr10/LOC‐HL catalyst exhibits the best catalytic performance and stability for OCM reaction at low temperature, that is, its CH4 conversion, C2+ selectivity, and yield at 450°C is 20.3%, 69.1%, and 13.2%, respectively; and its catalytic activity maintains stable during 3000 min. Insight into role of surface Sr‐sites would further improve catalytic performance at low temperature.

Fabrication of MgO nanorods blended cellulose acetate-based mixed matrix membranes for selective gas separation of H2/CH4, CO2/CH4 and H2/CO2: Effect of loading and pressure

The growing interest in polymer-based mixed matrix membranes (MMMs) in the field of gas separation encouraged the authors to fabricate MgO nanorods and cellulose acetate (MgO-X/CA) MMMs for the separation of H2/CH4, CO2/CH4, and H2/CO2 gases. The facile solution-casting, followed by solvent evaporation technique, was applied to fabricate MMMs. FE-SEM, EDS, FT-IR, XRD, DSC, and TGA characterization techniques were used to investigate the physico-chemical properties of fabricated MMMs, whereas the gas transport properties of MMMs were investigated using a gas permeation setup. Upon uniform MgO nanorods incorporation in CA polymer, the gas permeation through MMMs is improved due to disruption of the polymer chain. The influence of feed pressure and various loadings of nanorods (5, 10, and 15 wt%) on gas permeability and selectivity of CA based MMMs were investigated at 25 °C and 1–4 bar gas pressure. Based on the results, the MgO-15/CA MMMs achieved the highest H2 permeability of 77.80 Barrer which is higher than pure CA by 45%, with a two-fold increase in H2/CO2 selectivity and unchanged H2/CH4 selectivity. Meanwhile, MgO-5/CA MMMs revealed the highest CO2 permeability of 62.90 Barrer with an increased in CO2/CH4 selectivity from 22.30 to 24.30.

Improvement of the electrocatalytic performance of silicon carbide for oxygen reduction reaction induced by nitrogen doping

Replacing the precious metal catalysts with low-cost, efficient and stable catalysts for oxygen reduction reaction (ORR) is necessary to solve the challenge of sluggish reaction kinetics. Commercial SiC and aniline were used as a precursor and nitrogen source to prepare a series of nitrogen-doped SiC electrocatalysts (N-SiC) by a facile pyrolysis method at different temperature (800–1100 °C) under nitrogen atmosphere. Among four N-SiC samples, N-SiC-1000 possesses the highest surface area, uniform nanorod morphology, highest nitrogen content, and positively shifted binding energy. Based on these characteristics, the N-SiC-1000 catalyst demonstrates the best ORR catalytic activity manifested by relatively positive onset potential of 1.01 V, half-wave potential (0.87 V) and highest current density (5.38 mA cm−2 at 0.4 V), which is comparable to that of Pt/C, and has significantly better stability and outstanding methanol tolerance than that of Pt/C. The number of electrons transferred of N-SiC-1000 for ORR process is ∼3.97, indicating a 4-electron reaction pathway. These results show that N-SiC-1000 is a low-cost, efficient and stable ORR catalyst and can be used as a substitute for precious metal catalyst in fuel cells application.

One dimensional CeO2 nanorods/poly(ethylene oxide) solid composite electrolyte for all-solid-state lithium-ion batteries

The research of poly(ethylene oxide) (PEO)-based solid composite electrolyte with high ionic conductivity and excellent interfacial stability is the key to the development of all-solid-state lithium-ion batteries (ASSLIBs). Herein, uniform nanorod structured CeO2 fillers were controllably synthesized by electrospinning, which were subsequently filled into PEO polymer to prepare CeO2/PEO solid composite electrolyte. The addition of CeO2 nanorods can reduce both the glass transition temperature and the melting point of PEO polymer, and also interact with PEO and lithium bis(trifluoromethanesulphonyl)imide (LITFSI) by Lewis acid–base reaction. Therefore, the solid composite electrolyte exhibits a high ionic conductivity of 4.52 × 10−4 S/cm, a wide electrochemical stability window of about 4.8 V, and a good interfacial stability with Li at 55 °C. Moreover, the LiFePO4/Li ASSLIB divulges the discharging specific capacity of 165, 162, 156 and 146 mA⋅h/g at 0.2, 0.5, 1 and 2 C, respectively, and achieves the capacity retention of 90.3% after 150 cycles at 0.5 C. Consequently, one dimensional CeO2 nanorods can be considered as an alternative filler for polymeric solid electrolyte.

Electrochemical reconstruction and purification of silicon cutting waste to uniform silicon nanorods for improved lithium storage

This work reports the reconstruction and purification of silicon cutting waste (SCW) through a two-step molten salt electrochemical process, namely, a cathodic polarization mainly for the generation of Mg2Si followed by electrolysis of Mg2Si. After this process, the original uneven and irregular SCW particles were converted into uniform silicon nanorods (SNR, 30–50 nm in sizes), and the amount of impurity elements in SCW were significantly reduced. The as prepared SNR exhibits high specific capacity, good rate performance and cycle stability. It delivered a capacity of 3269 mAh g−1 at 1 A g−1 with an initial coulomb efficiency of about 91%. After 100 cycles, the SNR retained a capacity of 2429 mAh g−1, equivalent to 74% capacity retention, far superior to that of SCW (273 mAh g−1). This paper presents a simple, green, low cost and environmentally friendly method to convert SCW into value-added nanoscale silicon for lithium-ion battery anodes.

ZnCoMo nanorods modified with MoS2 nanosheets for supercapacitors and hydrogen evolution reaction

The preparation of dual-function nanomaterial electrode can meet the requirements of supercapacitor energy storage and the hydrogen emission reaction (HER), which makes the integrated design of energy reserves and hydrogen evolution possible. In this article, a two-step hydrothermal way that was consolidated with a continuous annealing process was used to build a graded mesoporous ZnCoMo@MoS2 nanocomposite electrode on the nickel foam framework. The entire surface of uniform ZnCoMo nanorods is tightly wrapped by MoS2 nanosheet arrays to form core-shell nanostructured electrodes, exposing the entire electrode's large specific surface area. Among them, oxide ZnCoMo is metalled by zinc cobalt molybdenum hybrid for short. The core-sheath nanostructure of the composite ZnCoMo@MoS2 It has high specific capacitance. The maximum accurate capacitance of this method is 1005.3 F g−1 (current density is 10mA/cm2). Under the condition of 50 mA/cm2, after 3000 cycles of discharge tests and charge, the capacity remains at 87.9% and the cycle stability is good. In addition, ZnCoMo@MoS2 nanocomposite electrode's overpotential is 125 mV at 10 mA/cm2 for hydrogen development in alkaline electrolyte and it has good stability. Lower overpotential and the larger specific capacitance are imputed to the synergistic result of MoS2 nanocomposites and ZnCoMo mainly. The results show that ZnCoMo@MoS2 core-shell heterostructure has high energy storage density and good hydrogen evolution performance, which provides a promising multi-functional active material for energy storage and hydrogen evolution.