Flower-like Nanostructures Research Articles

Role of synthesis temperature in the formation of ZnO nanoparticles via the Sol-Gel process

This study examines the synthesis of ZnO powder via the sol–gel method at temperatures of 25 °C and 60 °C. Characterization was conducted using standard techniques to investigate how these temperature conditions influence the physicochemical properties of the resulting material. XRD analysis confirmed high crystallinity with a pure hexagonal wurtzite structure, with average crystallite sizes of approximately 20 nm at 25 °C and 38 nm at 60 °C. Both SEM and TEM techniques established needle-like nanorods at 25 °C and nanoflower-like structures at 60 °C. Analyzing the high-resolution XPS spectra of the Zn2p and O1s photoelectron lines revealed a predominant Zn(II) state, with the contribution of ZnO increasing from 14.6 at.% to 41.6 at.% at higher temperatures. This change was accompanied by a decrease in defective oxygen and water content. Furthermore, DSC analysis revealed significant differences in thermal properties of ZnO powders synthesized at 25 °C and 60 °C, with distinct endothermic peaks around 120 °C corresponding to the evaporation of the solvent used in the synthesis process. The energy required for phase transitions was notably higher for the 25 °C synthesis, indicating greater thermal stability and energy demands compared to the 60 °C synthesis.

Composition-optimized NiGa-LDH on MOF-derived and cobalt-nanoparticles-embedded carbon flakes for enhanced potassium-ion storage

Layered double hydroxides (LDHs), renowned for their distinct nanostructures, efficient ion channels, and high specific capacitance, are promising electrode materials for supercapacitors (SCs). However, commercial applications remain limited due to constraints in the rate capabilities and cycling. The synergistic effects of the composites can be leveraged by pairing LDHs with carbon materials to enhance the conductivity for better SC characteristics. Herein, flaky Zeolitic Imidazolate Framework(ZIF)-67 is deposited on carbon cloth and calcined to produce the MOF-derived composite of carbon nanosheet-embedded nano-cobalt particles (CPEC) on the surface of the carbon cloth. Afterward, NiGa-LDH with a controllable Ni to Ga ratio is synthesized on the CPEC to form a flower-like hierarchical nanostructure NiGa-LDH/CPEC@CC. Co nanoparticles act as nucleation sites for cohesive formation within the carbon cloth framework. Ni2Ga1-LDH/CPEC@CC has the best properties, such as a specific capacitance of 729.6F g−1 at 1 mA cm−2 and 97.3 % capacitance retention at 2 mA cm−2. The asymmetric supercapacitor (ASC) consisting of Ni2Ga1-LDH/CPEC@CC//AC has an excellent energy density of 83.96 Wh kg−1 with a power density of 80 W kg−1. Density-functional theory (DFT) calculations of Ni2Ga1-LDH/CPEC@CC affirm a potassium ion adsorption energy of −2.127 eV and density of state (DOS) near the Fermi level. The study imparts theoretical and technical knowledge about the design of complex nanostructures from MOF precursors.

Hydrothermal Synthesis of ZnO Nanoflowers: Exploring the Relationship between Morphology, Defects, and Photocatalytic Activity

Two forms of flower-like ZnO nanostructures were synthesized using hydrothermal methods at various growth times/temperatures and zinc precursors. The morphology, structure, chemical composition, and optical properties of these ZnO nanoflowers were studied using a scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectrons spectroscopy (XPS), Raman spectroscopy, and UV–Vis spectroscopy. The SEM images revealed two forms of flower-like nanostructures, namely lotus- and tulip-like flower ZnO nanostructures. The XPS analysis revealed the oxidation state of the Zn and O elements, as well as the presence of OH groups on the surface of the lotus-like flower ZnO nanostructure. The XRD results revealed less crystallinity of the lotus-like ZnO nanoflowers (NFs) compared with the tulip-like ZnO NFs. The XRD results revealed the presence of Zn (OH)2 in the ZnO NFs. The Raman results confirmed less crystallinity of the lotus-like ZnO NFs. The estimated optical bandgap was 2.92 and 3.0 eV for the tulip- and lotus-like ZnO NFs, respectively. The tulip-like ZnO NFs showed superior photocatalytic degradation of methylene blue dye, verified via UV–Vis radiation, compared with the lotus-like ZnO NFs, which show the impact of the structure defects and OH- impurities on the photocatalytic performance of ZnO nanoflowers.

Hierarchical Nanostructures as Acoustically Manipulatable Multifunctional Agents in Dynamic Fluid Flow.

Acoustic waves provide a biocompatible and deep-tissue-penetrating tool suitable for contactless manipulation in in vivo environments. Despite the prevalence of dynamic fluids within the body, previous studies have primarily focused on static fluids, and manipulatable agents in dynamic fluids are limited to gaseous core-shell particles. However, these gas-filled particles face challenges in fast-flow manipulation, complex setups, design versatility, and practical medical imaging, underscoring the need for effective alternatives. In this study, flower-like hierarchical nanostructures (HNS) into microparticles (MPs) are incorporated, and demonstrated that various materials fabricated as HNS-MPs exhibit effective and reproducible acoustic trapping within high-velocity fluid flows. Through simulations, it is validated that the HNS-MPs are drawn to the focal point by acoustic streaming and form a trap through secondary acoustic streaming at the tips of the nanosheets comprising the HNS-MPs. Furthermore, the wide range of materials and modification options for HNS, combined with their high surface area and biocompatibility, enable them to serve as acoustically manipulatable multimodal imaging contrast agents and microrobots. They can perform intravascular multi-trap maneuvering with real-time imaging, purification of wastewater flow, and highly-loaded drug delivery. Given the diverse HNS materials developed to date, this study extends their applications to acoustofluidic and biomedical fields.

An In2O3/In2S3 photoanode-driven whole-cell biocathode sensor for sensitive detection of nitrate

Whole-cell biocathode sensor is a new form of self-regenerable biosensor and promising for environmental monitoring especially in the scenario with low organic substrate. However, external power supply such as electrochemical workstation is required to drive the biocathode reaction, which greatly limits its application. Herein, a new strategy based on the visible-light-driven whole-cell biocathode was proposed and validated for self-powered sensitive detections. To be specific, 1-OH phenazine was selected as the optimal electron shuttle for a Shewanella oneidensis MR-1 inoculated biocathode, which efficiently mediate the cathodic reaction at an electrode potential below −0.6 V (vs. SCE). Meanwhile, an In2O3/In2S3 photoanode with nanoflower-like structure was fabricated to match the kinetic of the biocathode. The photo-driven biocathode reduction was convinced by comparing with the performance of biocathode in the conventional three-electrode system. With this basis, a self-powered whole-cell biocathode sensor was developed for nitrate detection. An extreme low limit of detection of 0.028 μM (S/N=3) and linear detection range of 0.1–20 μM was achieved. Moreover, this biocathode sensor also exhibited excellent selectivity, reusability, accuracy, stability and was reliable for the detection of complex environmental samples. Therefore, this work developed a new photo-driven whole-cell biocathode sensor with excellent detection capacity of nitrate, which opens up new prospects for the development of high-performance biosensors.

Transition Metal (Molybdenum)-Doped Drug-like Conformational Nanoarchitectonics with Altered Valence States (Mn2+/Mn4+ and Mo5+/Mo6+) for Augmented Cancer Theranostics.

Despite the advancements in cancer therapy, delivering active pharmaceutical ingredients (APIs) using nanoparticles remains challenging due to the failed conveyance of the required drug payload, poor targeting ability, and poor biodistribution, hampering their clinical translation. Recently, the appropriate design of materials with intrinsic therapeutic functionalities has garnered enormous interest in the development of various intelligent therapeutic nanoplatforms. In this study, we demonstrate the fabrication of transition metal (molybdenum, Mo)-doped manganese dioxide (MnO2) nanoarchitectures, exhibiting diagnostic (magnetic resonance imaging, MRI) and therapeutic (chemodynamic therapy, CDT) functionalities. The facile hydrothermal approach-assisted Mo-doped MnO2 flower-like nanostructures offered tailorable morphologies in altered dimensions, precise therapeutic effects, exceptional biocompatibility, and biodegradability in the tumor microenvironment. The resultant defects due to doped Mo species exhibited peroxidase and oxidase activities, improving glutathione (GSH) oxidation. The two sets of variable valence metal ion pairs (Mn2+/Mn4+ and Mo5+/Mo6+) and their interplay could substantially improve the Fenton-like reaction and generate toxic hydroxyl radicals (•OH), thus achieving CDT-assisted antitumor effects. As inherent T1-MRI agents, these MnO2 nanoparticles displayed excellent MRI efficacy in vitro. Together, we believe that these conformational Mo-doped MnO2 nanoarchitectures with two pairs of variable valence states could potentiate drugless therapy in pharmaceutics.

Unravelling charge carrier dynamics for enhancement of photocatalytic performance in Pd/MoS2 nanocomposites for water remediation of real-world pollutants

In this study, Pd/MoS2 nanocomposites were successfully synthesized incorporating Pd nanoparticles into three-dimensional (3D) flower-like MoS2 nanostructures. The controlled introduction of Pd was aimed to optimize the photocatalytic performance of the resulting nanocomposites, which exhibited exceptional efficiency in degrading various organic pollutants and antibiotic tetracycline (TC) under simulated solar light irradiation. The nanocomposites with an optimized Pd concentration of 2.5 % demonstrated outstanding photocatalytic efficiency, achieving the degradation of Rhodamine B (RhB), Methylene blue (MB), TC by 98 %, 98 %, and 96 %, respectively, with specific interval of 40, 30 and 60 min. The reaction rate constant of the Pd/MoS2 nanocomposites was measured to be 0.7798 min−1 using pseudo first-order rate kinetics. The value is about 19 times higher than that of pure MoS2 (0.00414 min−1) for degradation of RhB. The improved photocatalytic performance of these nanocomposites can be attributed to several factors. Firstly, the incorporation of Pd nanoparticles substantially enhanced their light absorption capabilities, leading to an overall increase in photocatalytic efficiency. Moreover, the presence of Pd contributed to a large surface area, further enhancing the nanocomposite's photocatalytic potential. Importantly, the formation of a built-in electric field at Pd/MoS2 interface facilitated the efficient separation of the electron-hole pairs, extending the life time of these photoinduced charge carriers. This study offers valuable insights into development of MoS2-based photocatalyst, which hold significant promise for addressing water pollution challenges and making substantial contributions to the field of water purification and environmental remediation.

Enhanced photocatalytic degradation of Cr (VI) and organic pollutants using novel 3D/2D MoS2/SnS2 heterostructures for water remediation

In this study, 3D flower-like MoS2 nanostructures were synthesized using a hydrothermal technique to form heterostructures with 2D porous SnS2 nanosheets. The resulting 3D/2D MoS2/SnS2 heterostructures were evaluated for their photocatalytic abilities in removing Cr (VI), tetracycline (TC), and methylene blue (MB) under simulated solar irradiation. The results demonstrate that the MoS2/SnS2 heterostructures significantly outperformed pristine MoS2 and SnS2 in photocatalytic efficiency. Specifically, the MoS2/SnS2 photocatalysts achieved 99.9% degradation of Cr (VI) within 50 min, 96% degradation of TC in the same timeframe, and 99.9% elimination of MB in just 10 min. The reduction rate constant for Cr (VI) reduction by MoS2/SnS2 photocatalysts was 0.117 min−1, surpassing that of pure SnS2 (0.007 min−1) and MoS2 (0.0034 min−1) by 16 and 30 times, respectively. This outstanding performance is attributed to the heterojunction formation between SnS2 and MoS2, which suppresses the recombination of photogenerated charge carriers and provides abundant reactive sites due to their large specific surface area. The proposed photodegradation mechanism illustrates the facilitated migration of photogenerated charge carriers under light irradiation, enabled by the energy band alignment at the MoS2/SnS2 interface. These findings represent a significant advancement in the development of photocatalysts based on 3D flower-like MoS2 and porous SnS2 nanostructures, offering promise for applications in wastewater treatment and environmental remediation.

Flower-like nickel oxide nanostructures: Superior ammonia gas sensing and efficient dye removal behavior under UV–visible light illumination

In this study, we fabricated the NiO nanostructures using a straightforward solvothermal technique. The NiO nanoparticles were characterized using various analytical techniques. The FESEM images clearly show the flower-like structure of NiO nanoparticles. These nanostructures were then employed as a sensor to detect the presence of highly toxic ammonia (NH3) gas. The flower-shaped nanostructures of NiO played a vital role in improving sensing performance. Moreover, the NiO sensor displayed rapid response to 100 ppm ammonia at room temperature, with responses/recovery times of 40 s/44 s. This research holds promise as a viable approach for effectively sensing and detecting NH3 gas. The NiO exhibited excellent photocatalytic activity and degradation rates of 80% and 84.75% for Methyl orange (MO) and methylene blue dye (MB) respectively under UV-visible light irradiation. The NiO nanoflower remains unaffected after recycling MB dye degradation. This effective photocatalytic performance might be due to the formation of flower-like morphology. This underscores the potential of NiO as a promising candidate for applications in environmental and healthcare safety applications.

MoS2 Modified Aluminum Electrode for Detection of Calcium Oxalate through Electrochemical Oxidation

The disposal of electronic waste (E-waste), encompassing discarded items such as computers, televisions, fridges, cellphones, and associated cabling, presents a significant challenge to both societal welfare and environmental health. Addressing e-waste management is critical to achieving several of the Sustainable Development Goals (SDGs). This study introduces a novel approach to repurposing aluminum from discarded electrical cables for the creation of high-efficiency electrodes that can detect oxalic acid in human urine samples. The process involves stripping 2mm thick cables to yield 7cm long aluminum rods. These rods are then coated with MoS2 nanoparticles via a hydrothermal synthesis technique. X-ray diffraction (XRD) analysis confirms the presence of MoS2 in the 1T phase, while Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy provide insights into the vibrational modes and chemical composition. Field emission scanning electron microscopy (FESEM) imaging depicts the MoS2 as having a flower-like nanostructure composed of interwoven nanosheets. The resulting nanocomposite sensor demonstrates an enhanced electrical current response, along with notable selectivity and stability, likely due to the combined effects of the MoS2 materials. The sensor’s amperometric signal is directly correlated with the oxalate ion concentration within a range of 10 to 300 μM and exhibits a detection threshold as low as 2 μM. This sensor technique was evaluated alongside a standard colorimetric assay for measuring oxalic acid levels in urine specimens. Findings indicated a strong correlation (R=0.954) between oxalic acid concentrations assessed using the biosensor and those obtained through the colorimetric approach.Keywords: E-waste, Aluminum Electrodes, MoS2 Nanoparticles, Oxalic Acid Detection, and Electrochemical Sensing, Figure 1

Impact of reduced-graphene-oxide functionalization of flower-like zinc-oxide nanostructures on sensing performance of resistive ethanol gas sensor

This research presents a sensitive resistive ethanol gas sensor based on reduced graphene oxide (rGO)-functionalized Zinc oxide nanoflowers (ZnO NFs). Upon completion of synthesis, the resulting nanostructures were cast onto the photolithographed silver interdigitated electrodes positioned on an Al2O3 substrate. The graphene oxide (GO) with a low oxidation degree was synthesized using a Hummer's method. In the pursuit of optimizing sensing performance, rGO-functionalized ZnO NFs were synthesized through a one-pot hydrothermal process, utilizing different initial quantities of GO (0 mg, 2 mg, 8 mg, and 12 mg). According to the gas sensing measurements, the fabricated sensor with 8 mg initial GO showed the highest response to ethanol at 250 °C. The results show that the GO addition reduced the optimal working temperature of the pure ZnO NFs from 350 °C to 250 °C. The sensor exhibited a good selectivity, repeatability, and high long-term stability. Enhanced ethanol sensing response of the optimized gas sensor was related to the formation of p-n heterojunction between p-type rGO (formed during hydrothermal process at 200 °C) and n-type ZnO and the presence of the optimal amount of rGO on the surface of NFs. The results obtained in this investigation stress the significance of pinpointing the optimal quantity of GO for producing rGO-ZnO nanoflowers with the highest possible sensitivity to ethanol gas.

Aptasensor based on gold nanostructure-decorated 2D Cu metal-organic framework nanosheets for highly sensitive and specific electrochemical lipopolysaccharide detection.

Detecting lipopolysaccharide (LPS) using electrochemical methods is significant because of theirexceptional sensitivity, simplicity, and user-friendliness. Two-dimensional metal-organic framework (2D-MOF) that merges the benefits of MOF and 2D nanostructure has exhibited remarkable performance in constructing electrochemical sensors, notably surpassing traditional 3D-MOFs. In this study, Cu[tetrakis(4-carboxylphenyl)porphyrin] (Cu-TCPP) and Cu(tetrahydroxyquinone) (Cu-THQ) 2D nanosheets were synthesized and applied on a glassy carbon electrode (GCE). The 2D-MOF nanosheets, which serve as supporting layers, exhibit improved electron transfer and electronic conductivity characteristics. Subsequently, the modified electrode was subjected to electrodeposition with Au nanostructures, resulting in the formation of Au/Cu-TCPP/GCE and Au/Cu-THQ/GCE. Notably, the Au/Cu-THQ/GCE demonstrated superior electrochemical activity because of the 2D morphology, redox ligand, dense Cu sites, and improved deposition of flower-like Au nanostructure based on Cu-THQ. The electron transfer specific surface area was increased by the improved deposition of Au nanostructures, which facilitates enriched binding of LPS aptamer and significantly improved thedetection performance of Apt/Au/Cu-THQ/GCE electrochemical aptasensor. The limit of detection for LPS reached 0.15fg/mL with a linear range of 1fg/mL - 100pg/mL. Theproposed aptasensor demonstrated the ability to detect LPS in serum samples with satisfactory accuracy, indicating significant potential for clinical diagnosis.

Synergistic engineering of Ag doping and P vacancies in nanoflower-like Ni2P for acrylamide-assisted electrolysis of seawater splitting

Given the vast abundance of seawater resources on Earth, direct electrolysis of seawater as an attractive approach for hydrogen fuel production. Seawater electrolysis coupled with the acrylamide (AA) oxidation replacing oxygen evolution is an effective way for simultaneously treating AA wastewater and producing H2. Herein, we propose Ag-doped nanoflower-like Ni2P on Ni foam (Ag-Ni2P NF) and generate P vacancies by treatment with NaBH4 solution (Ag/B-Ni2P NF) to serve as a bifunctional catalyst. The Ag/B-Ni2P NF can replace oxygen evolution reaction (OER) with AA oxidation reaction (AOR) in anode (235 mV to drive 100 mA cm−2) and hydrogen evolution reaction (HER) in cathode (295 mV to drive 100 mA cm−2). The density functional theory (DFT) calculations and experimental results collectively elucidate the factors contributing to the enhanced catalyst activity. Due to its nanoflower-like structure, robust Ni−B bond interaction, P vacancies, large surface area and strong electrocatalytic activity, the Ag/B-Ni2P NF exhibited high stability and reusability in seawater. DFT calculations reveal that Ag atoms facilitate strong metal-support interactions, while P vacancies create adsorption sites for B integration. The potential for AOR in seawater can be minimized to 1.91 V, generating a current density of 100 mA cm−2 using Ag/B-Ni2P NF in a two-electrode system. As a result, AA oxidation and H2 production in a single system can efficiently reduce energy consumption while promoting environmental protection in seawater resources.

Aluminum doped CuS nanocrystals for efficient antibacterial activity via photothermal and photodynamic pathways

The overuse of antibiotics has led to the emergence of drug-resistant bacteria, presenting a significant risk to public health and human well-being. A novel antibacterial material with safe and effective antibacterial properties is a viable strategy to address these issues. In this work, Al ions doped CuS particles (CuS@Al) with a flower-like nanostructure were synthesized through a simple hydrothermal method, exhibiting good photothermal and photodynamic antibacterial properties. The morphological, microstructural and crystallinity of CuS@Al were evaluated by SEM, EDS, TEM, FTIR, XRD and XPS analyses. The introduction of Al ions significantly enhanced the photothermal effects of CuS@Al, and the temperature increased from 50.7 ℃ (CuS) to 58.1 ℃ (CuS-6) under irradiation (808 nm, 2.0 W·cm−2, 10 min). The resulting CuS@Al exhibited a good photothermal conversion efficiency, effective release of reactive oxygen species (ROS), and remarkable photothermal antibacterial activity. Both E. coli and S. aureus were completely inactivated by CuS@Al (0.5 mg/mL) under photodynamic conditions. The synthesis of CuS@Al provides a strategy for creating highly effective antibacterial materials in particulate form.

Exploring the multifunctionality of MoS2 and MoSe2 nanostructures: Enhanced ammonia sensing, antimicrobial activity and organic dye adsorption

Nanostructured materials have emerged as a focal point in materials science, primarily due to their unique physical and structural characteristics that facilitate a wide range of applications. Multifunctional activity derived from a single material has been attracting attention recently. This study focuses on synthesizing the Molybdenum disulfide (MoS2) and Molybdenum diselenide (MoSe2) using the hydrothermal method of synthesis. The nanostructures thus produced were studied for various environmental remediation applications, including ammonia gas sensing, antimicrobial activities, and the removal of methyl orange (MO) dye from aqueous solutions. Herein, the flower-like MoS2 nanostructures exhibit remarkable ammonia-sensing capabilities with a response (Δ R/Rair%) of 100 % at room temperature when exposed to 20 ppm of ammonia gas. Additionally, they were also effective in the removal of MO from aqueous solutions. Furthermore, the antimicrobial activity of the synthesized samples was also studied against Escherichia Coli (E. Coli) (MTCC443) and Saccharomyces cerevisiae (MTCC170) using the agar diffusion method. The antibacterial activity of MoS2 and MoSe2 against E. coli produced inhibition zones of 18 mm and 22 mm, respectively. The antifungal activity against Saccharomyces cerevisiae resulted in inhibition zones of 11 mm and 16 mm, respectively, for 0.1 μg of MoS2 and MoSe2. The results indicated that MoSe2 exhibits superior antibacterial and antifungal activities compared to MoS2. This enhanced activity is likely attributable to the nanorod-like morphology of MoSe2, which facilitates easier penetration into microbial cell walls. Overall, this study underscores the multifunctional potential of these synthesized nanostructured materials, highlighting their applicability in environmental remediation.

Smart nanozymes coupled with dynamic magnet field and laser exposures for cancer therapy

Developing nanozymes for cancer therapy has attracted great attention from researchers. However, enzymes-loaded magnetic particles triggered by both a low-frequency vibrating magnetic field (VMF) and laser for inhibiting tumor growth have never been reported. Herein, we developed a magnetic nanozyme with 3D flower-like nanostructures for cancer therapy. Specifically, the flower-like nanozymes exposed to a VMF could efficiently damage the mitochondrial membrane and cell structure, and inhibit tumor growth through magneto-mechanical force. In parallel, magnetic nanozymes in a weak acid environment containing glucose could generate abundant hydrogen peroxide through glucose oxidase-catalyzed oxidation of glucose, and further significantly promote the Fenton reaction. Interestingly, both glucose oxidase- and Fenton-based catalytic reactions were significantly promoted by the VMF exposure. Flower-like magnetic nanospheres upon a near-infrared laser irradiation could also damage cancer cells and tumor tissues through photothermal effect. The cell-killing efficiency of magnetic nanozymes triggered by the VMF or laser significantly increased in comparison with that of nanozymes without exposures. Mouse tumors grown after injection with magnetic nanozymes was inhibited in a significant way or the tumors disappeared after exposure to a VMF and laser due to the synergistic effect of four major stimuli, viz., magneto-mechanical force, photothermal conversion, improved Fenton reaction, and intratumoral glucose consumption-based starvation effect. This is a great platform that may be suitable for treating many solid tumors.

Synthesis of ZnO@Fe2O3 microflowers with enhanced performance in volatile organic compound detection

Metal-oxide semiconductor is widely applied in gas sensor for volatile organic compound detection. However, these sensors usually exhibit poor selectivity and inferior sensitivity. Here, ZnO@Fe2O3 microflowers were synthesized using FeOOH microflowers as precursors via a simple solution reaction route, followed by heat treatment. The ZnO@Fe2O3 microflowers were characterized using a series of techniques, and their sensing responses to volatile organic compounds (VOCs) were evaluated in comparison with those of pristine Fe2O3. The ZnO@Fe2O3 microflower sensor exhibited better responses to several gases, especially acetone, with a response of 74.3 towards 100 ppm acetone, which is 2.85 times higher than that of the Fe2O3 microflower sensor. The sensor also presented high selectivity, reproducibility, and stability in sensing different VOCs. The large specific surface area, heterostructure, favorable hierarchical flower-like nanostructure assembled by the nanosheets, and high porosity of the ZnO@Fe2O3 microflowers contributed to its enhanced gas-sensing responses. Overall, this synthetic strategy for fabricating flower-like ZnO@Fe2O3 nanostructures can be widely applied.

Growth process of boehmite with large particles in ammonia system

The development of a novel technology for extracting aluminum resources from coal fly ash through direct leaching with an ammonium hydrogen sulfate solution represents a significant advancement. A pivotal stage within this process is the reaction crystallization between NH4Al(SO4)2·12H2O solid and NH3·H2O. Despite its many benefits, the fine particle size of the resultant product has impeded its widespread adoption. To tackle this challenge, this study concentrated on examining the growth mechanism of boehmite with larger particles in the presence of ammonia. Analysis revealed a distinct morphological evolution process for large-particle boehmite, progressing from a flaky morphology to a flower-like nanostructure with flaky features, and then further transitioning into particles displaying flower-like nanostructures and culminating in the formation of large particles with smooth surfaces. Initially, the early stages of crystallization were governed by kinetic factors, followed by a self-assembly phase, ultimately resulting in the final morphology of large particles, dictated by thermodynamic considerations. Density functional theory calculations underscored the significant role of H2O molecule adsorption in boehmite's growth trajectory, leading to the formation of pseudo-boehmite and inducing shifts in the X-ray diffraction peaks. The growth units remained integral throughout the entirety of the crystal growth process.

Tuning ZnSe nanostructures for enhanced ammonia sensing at room temperature

Nanostructured materials, defined by their distinctive physicochemical properties at the nanometer scale, facilitate the innovation of sophisticated applications through their inherent size-dependent phenomena and surface characteristics. In this study, we explore the synthesis of ZnSe nanostructures with distinct spherical and flower-like morphologies by varying the concentration of Ethylenediamine tetraacetic acid (EDTA). Our findings reveal that higher concentrations of EDTA facilitate flower-like morphologies, which provide a large surface area desired for gas sensing applications. Herein, the as-synthesized ZnSe nanostructures were applied for ammonia (NH3) sensing at room temperature at different concentrations to evaluate their performance. The results obtained indicate that ZnSe nanostructures with flower-like morphology exhibit superior sensing capabilities, demonstrating a good response (ΔR/Rair)% of 71 % compared to the 61 % response observed for spherical ZnSe nanostructures for 20 ppm NH3 gas, measured at room temperature. Additionally, the flower-like ZnSe nanostructures show significantly enhanced response and recovery times, demonstrating their potential as efficient materials for NH3 detection at room temperature.

Flower-Branch-Like carbon Microtube/Vanadium Selenide: A highly efficient electromagnetic wave absorbing composite

The unique layered structure and adjustable band gap of transition metal dichalcogenides (TMDs) have prompted extensive investigations into their potential for electromagnetic wave absorption (EWA). Vanadium selenide (VSe2), a notable representative of TMDs, has a larger interlayer spacing (6.1 Å) and higher conductivity (1 × 10-3 S/m), which has high advantageous in EWA applications. However, the existing research on the use of VSe2 for EWA remains relatively limited. Herein, a flower-branch-like carbon microtube/vanadium selenide (CMT/VSe2) composite was successfully synthesized via a facile solvothermal method. This composite material is composed of flower-like VSe2 nanostructures integrated with carbon microtubes. Importantly, the EWA properties of this composite can be effectively tailored by adjusting the concentration of the VSe2 precursor. The CMT/VSe2 composite exhibited a remarkable minimum reflection loss (RL) of −60.54 dB in the Ku-band, with a matching thickness of 2.27 mm. Moreover, the effective absorption bandwidth reached 6.38 GHz. These results demonstrate the great potential of this CMT/VSe2 composite material as a highly efficient EWA material. Furthermore, this work broadens the application of two-dimensional TMDs in the area of EWA.