Shape Of Nanostructures Research Articles

Revolutionizing energy evolution: SnS-Sn2S3 layered structures as exceptional electrocatalytic materials for H2 and O2 generation

In this paper, we prepared the SnS-Sn2S3 layered structure using the in-situ solvothermal method for hydrogen evolution (HER) and oxygen evolution reaction (OER). XRD and HRTEM confirm the successful synthesis of the orthorhombic crystal structure of the SnS-Sn2S3. Further, SEM images demonstrate the layered shape of the SnS-Sn2S3 nanostructure, promoting the formation of more active sites on the surface for better electrocatalytic activities. Interestingly, during OER investigation, the SnS-Sn2S3 catalyst depicts an overpotential of 359 mV (10 mA cm−2) and a Tafel slope of 90.1 mV dec-1. However, during HER investigation, the SnS-Sn2S3 catalyst describes an overpotential of 162 mV (-10 mA cm−2) and a Tafel slope of 107.6 mV dec-1. Moreover, the SnS-Sn2S3 catalyst unveils superb stability for 2.3 h at 10 mA cm−2 for OER and 4.0 h at −10 mA cm−2 for HER. The OER and HER reaction mechanisms were also discussed to explore the kinetics rate of SnS-Sn2S3 catalyst.

Fabrication of multilevel metalenses using multiphoton lithography: from design to evaluation.

We present a procedure for the design of multilevel metalenses and their fabrication with multiphoton-based direct laser writing. This work pushes this fast and versatile fabrication technique to its limits in terms of achievable feature size dimensions for the creation of compact high-numerical aperture metalenses on flat substrates and optical fiber tips. We demonstrate the design of metalenses with various numerical apertures up to 0.96, and optimize the fabrication process towards nanostructure shape reproducibility. We perform optical characterization of the metalenses towards spot size, focusing efficiency, and optical functionality with a fiber beam collimation design, and compare their performance with refractive and diffractive counterparts fabricated with the same technology.

Application of TiO2-loaded fly ash-based geopolymer in adsorption of methylene blue from water: Waste-to-value approach

This paper aims to explore the removal of methylene blue from wastewater using fly ash-based geopolymer (FAG) modified with titanium dioxide (TiO2) nanoparticles referred to as FAG-TiO2. Using several analytical techniques, the modified geopolymer was physically and chemically characterized. Additionally, it was investigated how pH, MB concentration, and temperature affected the MB adsorption process utilizing FAG-TiO2. Scanning electron microscopy images exhibited a porous morphology. Furthermore, transmission electron microscopy images revealed a nanostructured shape, with nanoparticles clumping together to form small channels suitable for MB adsorption. The stretching vibration of the alumina silicate was seen using the Fourier transform infrared, indicating that geopolymerization was successfully conducted. The developed FAG-TiO2 showed a remarkable capacity for MB adsorption from the aqueous phase. The Langmuir isotherm model was the best-fitting adsorption model, with a maximum adsorption capacity of 103.19 mg/g at pH 6 and 35 °C. The thermodynamics investigations revealed negative values for Gibbs free energy (ΔGo), emphasizing the spontaneous nature of the processes. While the positive entropy (ΔSo) indicated a significant affinity between the two phases, the positive enthalpy (ΔHo) implies an endothermic reaction. Additionally, hydrogen bonds, n-π, and electrostatic interactions between MB and FAG-TiO2 facilitated the adsorption process. Furthermore, desorption studies with two different chemicals were used to investigate MB retention onto FAG-TiO2. The adsorbents were desorbed using an HCl (0.5 M) reagent where the maximum MB desorption reached 41.95%. Real wastewater samples were also tested, and promising results were found, indicating the possible use of the prepared adsorbent in industrial applications.

Effect of Cu substitution on magnetic and photocatalytic properties of Mn–ZnFe2O4 nanoparticles

The citrate approach was employed to successfully synthesize Mn0.4Zn0.6−xCuxFe2O4 (MZCF) with a nanostructured shape. A thorough examination was conducted on the microstructural, magnetic, and optical properties of the nanoparticles obtained. The X-ray diffraction (XRD) patterns revealed that all of the compositions exhibit a high degree of single-phase spinel formation. The experimental findings indicate that the introduction of copper ions leads to a reduction in both lattice constant and porosity, while concurrently resulting in an increase in the theoretical X-ray and bulk densities. The analysis of UV–Vis spectroscopy indicated that MZCF exhibited a direct band gap falling within the range of 1.61–1.78 eV. The magnetic characteristics were assessed through the analysis of hysteresis plots. The introduction of copper (Cu) content leads to notable improvements in the saturation (Ms) and remanent magnetization (Mr) values, which range from 40.21 to 58.78 and 4.46–10.54 emu/g, respectively. The assessment of the microwave frequency response has verified the appropriateness of MZCF nanoferrites for application within the frequency spectrum spanning from 8 to 13 gigahertz. The nanoparticles exhibit improved magnetic properties, suggesting their potential appropriateness for applications involving high-frequency microwave absorption and switching. Furthermore, the nanoparticles Mn0.4Zn0.6Fe2O4 and Mn0.4Zn0.2Cu0.4Fe2O4 were subjected to analysis utilizing a solar light simulator in order to induce degradation of MB dye.

Ion beam processing of DNA origami nanostructures.

DNA origami nanostructures are emerging as a bottom-up nanopatterning approach. Direct combination of this approach with top-down nanotechnology, such as ion beams, has not been considered because of the soft nature of the DNA material. Here we demonstrate that the shape of 2D DNA origami nanostructures deposited on Si substrates is well preserved upon irradiation by ion beams, modeling ion implantation, lithography, and sputtering conditions. Structural changes in 2D DNA origami nanostructures deposited on Si are analyzed using AFM imaging. The observed effects on DNA origami include structure height decrease or increase upon fast heavy ion irradiation in vacuum and in air, respectively. Slow- and medium-energy heavy ion irradiation results in the cutting of the nanostructures or crater formation with ion-induced damage in the 10 nm range around the primary ion track. In all these cases, the designed shape of the 2D origami nanostructure remains unperturbed. Present stability and nature of damages on DNA origami nanostructures enable fusion of DNA origami advantages such as shape and positioning control into novel ion beam nanofabrication approaches.

C60 fullerene nanoparticles permeability through the model lipid envelope of coronavirus and their anticoronavirus effect in the in ovo system

Background: An urgent problem of modern biomedicine is the search for potential ways to reduce the spread of coronavirus infections in human and animal populations and eliminate the impact of coronavirus on their bodies. Aim of the work was to determine the structural organization of C60 fullerenes in a model cell medium, to assess their potential ability to penetrate the model lipid envelope of a coronavirus, thus destroying its integrity, as well as the effectiveness of the anticoronavirus action in the in ovo system. Methods: The research was conducted using the Gromacs 2020 software package and the Charmm36 force field. The CHARMM-GUI web resource was used to construct the lipid envelope of a coronavirus. Virological and toxicological methods were used in the in ovo experiments. Results: It is shown that at the initial stages of molecular dynamics C60 fullerene forms small nanoclusters in the amount of 7–16 molecules, which is affected by the initial concentration of C60 fullerene in a model cell medium. At the same time, the shape of nanostructures for the number of molecules over 16 may differ from the correct spherical shape. It was established that C60 fullerene and its nanoclusters are able to penetrate inside the lipid envelope of a coronavirus. In particular, a single C60 molecule can migrate, completely embed itself in the lipid envelope, or move within it. It was found that C60 fullerene aqueous solution, at the maximum permissible concentration (MPC) of 30 μg/embryo, reduces the infectious activity of the chicken infectious bronchitis (CIB) coronavirus when it is used 1, 2 and 4 h after the infection of a sensitive biological system with a coronavirus. Conclusions: It is shown that aggregation of C60 fullerene in a model cell medium can occur in different ways: either before penetration into the lipid envelope of a coronavirus, or inside it. C60 fullerenes, both individually and as part of nanoclusters, are able to form pores in the envelope of a coronavirus, destroying its integrity, which possibly leads to disruption of the corresponding stages of its replication cycle and attachment to cell receptors. It was established that C60 fullerene aqueous solution, when used in the MPC value, shows antiviral activity against the CIB coronavirus in its early stages of interaction with the cell (1–4 h).

Theoretical Assessment on Shape-Dependent Optical Properties of Gold Nanostructures

In the current work, detailed investigations on shape-dependent optical properties of gold nanostructures are carried out using the finite element method. The key objective of the work was to explore the optical response of differently shaped gold nanostructures. Five differently shaped gold nanostructures i.e. nanopyramid, nanocylinder, nanocone, nanosphere, and nanocube were considered to study the optical properties including skin depth, relative permittivity, refractive index, absorption cross-section, and extinction cross-section. The optical properties of gold appeared to depend on the shapes of nanostructures. The nanostructures with sharp apexes exhibit more skin depth in contrary to those having smooth surfaces. The surface Plasmon resonance (SPR) for the nanostructures was found maximum at 540 nm throughout the calculated range of wavelengths and the intensity of all the curves depends on the shape of the nanostructure.

Selective Uptake Into Inflamed Human Intestinal Tissue and Immune Cell Targeting by Wormlike Polymer Micelles.

Inflammatory bowel disease (IBD)has become a globally prevalent chronic disease with no causal therapeutic options. Targeted drug delivery systems with selectivity for inflamed areas in the gastrointestinal tract promise to reduce severe drug-related side effects. By creating three distinct nanostructures (vesicles, spherical, and wormlike micelles) from the same amphiphilic block copolymer poly(butyl acrylate)-block-poly(ethylene oxide) (PBA-b-PEO), the effect of nanoparticle shape on human mucosal penetration is systematically identified. An Ussing chamber technique is established to perform the ex vivo experiments on human colonic biopsies, demonstrating that the shape of polymeric nanostructures represents a rarely addressed key to tissue selectivity required for efficient IBD treatment. Wormlike micelles specifically enter inflamed mucosa from patients with IBD, but no significant uptake is observed in healthy tissue. Spheres (≈25nm) and vesicles (≈120nm) enter either both normal and inflamed tissue types or do not penetrate any tissue. According to quantitative image analysis, the wormlike nanoparticles localize mainly within immune cells, facilitating specific targeting, which is crucial for further increasing the efficacy of IBD treatment. These findings therefore demonstrate the untapped potential of wormlike nanoparticles not only to selectively target the inflamed human mucosa, but also to target key pro-inflammatory cells.

Fast and scalable production of crosslinked polyimide aerogel fibers for ultrathin thermoregulating clothes

Polyimide aerogel fibers hold promise for intelligent thermal management fabrics, but their scalable production faces challenges due to the sluggish gelation kinetics and the weak backbone strength. Herein, a strategy is developed for fast and scalable fabrication of crosslinked polyimide (CPI) aerogel fibers by wet-spinning and ambient pressure drying via UV-enhanced dynamic gelation strategy. This strategy enables fast sol-gel transition of photosensitive polyimide, resulting in a strongly-crosslinked gel skeleton that effectively maintains the fiber shape and porous nanostructure. Continuous production of CPI aerogel fibers (length of hundreds of meters) with high specific modulus (390.9 kN m kg−1) can be achieved within 7 h, more efficiently than previous methods (>48 h). Moreover, the CPI aerogel fabric demonstrates almost the same thermal insulating performance as down, but is about 1/8 the thickness of down. The strategy opens a promisingly wide-space for fast and scalable fabrication of ultrathin fabrics for personal thermal management.

In situ tuning and investigating the growth process of size controllable gold nanoparticles and statistical size prediction analysis

A critical understanding of the formation and growth process of gold nanoparticles (GNPs) is crucial, in order to synthesize monodisperse gold nanocrystals of controllable size and shape in a predictable way. GNPs of different shapes and sizes can be produced by altering different physicochemical reaction conditions, such as pH, temperature, and the ratio of reactants. The significant variations in the morphological features of GNPs can be monitored in situ in a time-dependent manner by using UV–visible spectroscopy. In this study, we have synthesized seedless GNPs by reduction of HAuCl4 by using various molar ratios of HEPES and Na2HPO4. The shape and the geometry of the gold nanostructures were optimized by varying the pH (5, 7, and 9) of the HEPES, molar concentrations of disodium phosphate to HAuCl4, and reaction temperatures (20 °C, 40 °C, and 60 °C). The changes in the color of the reaction mixtures over time were recorded in situ in terms of the absorbance of the UV–visible light to tune and investigate the growth process of gold nanostructures. Transmission electron microscopic (TEM) images indicated that the gold nanostructures are anisotropic, stable, and exist in the size range of < 1–100 nm. The present study also confirms that the change in the color of nanostructure reaction mixtures is a function of the surface plasmon resonance bands under the influence of physicochemical reaction conditions and corroborates with the size and shape of nano-gold. Physicochemical parameters such as temperature, pH, and the molar concentration of the reactants act synergistically to influence the growth, molecular mechanics, and reaction thermodynamics that aid to affect the particle size, shape, and surface corona of the GNPs. By tracking the growth process, we can confirm that the nucleation, growth process, size, and shape of the gold nanostructures depend on the HEPES free radicals and phosphate ions which cluster to form polymeric chains on the gold nanocore. The present study's findings explain the growth process of the GNPs of various colors that can be observed by the naked eye and have promising applications, for example in the development of the biosensing rapid lateral flow immunoassays (LFIA) for the detection of mycotoxins in food samples.

Synthesis and growth mechanism of ZnO nanocandles using thermal evaporation and their efficient CO sensing performance

We report on the single step grown ZnO nanocandles without adding any catalyst for efficient CO gas sensing application. A simple, scalable, and cost-effective thermal evaporation technique was employed for the growth of ZnO nanostructures on alumina substrate at 600 °C. It was observed that oxygen ambient (variation in oxygen flow rates from 20 to 40 sccm) strongly influences the shape and size of the ZnO nanostructures (i.e., the formation of nanocandles or nanorods). The as grown ZnO nanostructures were characterized using various techniques such as X-ray diffraction, Field emission scanning electron microscopy, photoluminescence, and X-ray photoelectron spectroscopy. Further, a comprehensive analysis of the CO gas sensing performance of each sample was recorded under various conditions, and the corresponding mechanism was reported. We have achieved the maximum sensor response (SR%) ∼ 78.3% along with a response/recovery time ∼ 59.5 s/109.4 s towards 91 ppm of CO gas at 400 °C for the sample synthesized at 40 sccm oxygen gas flow rate (i.e., for nanocandles). While, a relatively lower SR ∼ 70.1% and ∼ 64.1% and higher response/recovery time of ∼ 77.8 s/118.6 s and ∼ 84.6 s/122.1 s were obtained for the samples synthesized at 30 sccm and 20 sccm, respectively (i.e., for nanorods). Moreover, the calculated detection limit for ZnO nanocandles was 110 ppb. The selectivity test shows that the ZnO nanocandles are highly responsive to CO gas and exhibits long term stability (tested over 360 days). Thus, ZnO nanocandles can be used for the fabrication of robust CO gas sensors.

Confined self‐assembly of block copolymers in emulsion droplets: Preparation, shape and internal structure, and applications

AbstractConfined assembly of block copolymers (BCPs) in emulsion droplets receives considerable attention since self‐assembly in flexible geometry pioneers an efficient yet promising route to prepare unconventional polymer materials that cannot be acquired in the bulk state or solution. The deformability and interfacial property regulation of the soft emulsion droplets offer tremendous potential for the design and construction of BCP nanoparticles with desired shape and internal nanostructures. This review summarizes the recent developments of BCP assembly behavior in three‐dimensional (3D) soft oil emulsion droplets, including preparation methods, shape and internal structure control, as well as advanced applications of the generated BCP materials. Typical experimental parameters and post processes, including intrinsic property of BCPs, surfactant property, confinement degree, interfacial instability, additives, evaporation rate, post‐annealing, and disassembly, that have significant influence on the precise control and regulation of emulsion interface properties and the prepared assembly structures are well systematically summarized. Finally, the challenges and further perspective in this area are presented.

Hybrid integration of ensemble nitrogen-vacancy centers in single-crystal diamond based on pick-flip-and-place transfer printing

Incorporating color centers in diamond with mature integrated photonics using hybrid integration techniques such as transfer printing provides a promising route toward scalable quantum applications. However, single-crystal diamond nanostructures fabricated using current etching technologies have triangular bottoms that are unsuitable for conventional pick-and-place integration. Herein, we present an alternative approach for deterministically integrating diamond nanostructures on chip. We demonstrate the hybrid integration of a diamond triangular nanobeam containing a nitrogen-vacancy ensemble on an SiO2 chip by picking it up using a weak adhesive film, flipping it, and transferring it to a stronger one. This “pick-flip-and-place” approach provides a flat diamond-chip interface, enabling the high-yield hybrid integration regardless of the shape of diamond nanostructures. Additionally, diamond nanofabrication is facilitated by transfer-printing hard masks for diamond etching. We also show that the integrated diamond nanobeam functions as a nanoscale quantum sensor. Our proposed approach paves the way toward scalable hybrid-diamond quantum photonics.

Enhanced self-powered and visible-range photodetector performance of Ag2S nanostructures by Cu concentrations

In the present research, silver sulfide (Ag2S) nanostructures were grown using the sonochemical method. The effect of copper (Cu) dopant in different concentrations was investigated on the physical and electrical properties, and then their performance as photodetectors were evaluated. It was found that Cu doping shifted the XRD peaks of Ag2S to higher angles and increased the crystallite size. FESEM images showed that adding Cu in different concentrations increased the size of Ag2S nanostructures, while the spherical shape of Ag2S nanostructures did not change. XPS analysis confirmed the formation of the Ag2S phase, being consistent with XRD results and incorporation of Cu atoms in substitution positions in the crystalline structure. The study of optical properties indicated that the absorption intensity of Cu-doped Ag2S nanostructures decreased compared to the un-doped sample. Electrical analyses revealed that adding Cu concentrations increased the density of electrical carriers. The charge transfer process was studied using the current-voltage curve under different conditions. The evaluation of optoelectronic properties also demonstrated that the presence of Cu concentrations improved the quality parameters of Ag2S nanostructures as a self-powered photodetector in the visible-range wavelengths.

On the Development of Injection Cathode Electrodes for EHD Transducers

Purpose To study the possibility of changing cathode injection in a grid axisymmetric EHD transducer with planeparallel modified electrodes.Methods. An estimate of the influence of the edge effect of electrode grids on the surface conductivity in the periphery of the interelectrode gap was obtained by numerical simulation, and the optimal geometry of the electrode holders of the grid EHD transducer was determined. Using the method of numerical calculation in the software environment Agros 2D, as well as using the analysis of SEM scans and the method of estimating the form factor of structures, the parameters of local electric fields of the structures of the surfaces of wires of grid electrodes modified during laser scribing were obtained.Results. The results of the development of a grid system of electrodes for electrohydrodynamic converters with enhanced cathodic charge injection are presented. The influence of the edge effect on the operation of EHD transducers is analyzed. The possibility of improving the grid electrode system of a model EHD pump is described. The composition and shape of microand nanostructures after scribing on the FMark-20RL laser marking complex have been studied. A qualitative estimate of the local electric field strength on nanostructures obtained by laser scribing of brass grids with a characteristic radius of 50 nm is made, which indicates an increase in the cathode injection of negative charges in the EHD system. With a distance between the electrodes of 1.5 mm and a potential difference between the electrodes of 1.5 kV/cm, the magnitude of the local tension at the top of the nanostructure with a curvature radius of about 50 nm can reach 5.5⋅107 V/cm.Conclusion. Laser scribing in the form of concentric circles of brass grid electrodes makes it possible to intensify cathodic charge injection by amplifying local electric fields from microand nanostructures. The use of plexiglass dielectric holders can reduce surface leakage currents at the periphery of grid electrodes.

Morphology Transition with Temperature and its Effect on Optical Properties of Colloidal MoS2 Nanostructures.

Morphology plays a crucial role in determining the chemical and optical properties of nanomaterials due to confinement effects. We report the morphology transition of colloidal molybdenum disulfide (MoS2) nanostructures, synthesized by a one-pot heat-up method, from a mix of quantum dots (QDs) and nanosheets to predominantly nanorods by varying the synthesis reaction temperature from 90 to 160 °C. The stoichiometry and composition of the synthesized QDs, nanosheets, and nanorods were quantified to be MoS2 using energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses. A nanostructure morphology transition due to variation in the reaction temperature resulted in a photoluminescence quantum yield enhancement from 0 to 4.4% on increasing the temperature from 90 to 120 °C. On further increase in the temperature to 160 °C, a decrease in the quantum yield to 3.06% is observed. Red-shifts of ≈18 and ≈140 nm in the emission maxima and absorption edge, respectively, are observed for the synthesized nanostructures with an increase in the reaction temperature from 90 to 160 °C. The change in the quantum yield is attributed to the change in shape and hence confinement of charge carriers. To the best of our knowledge, microscopic analysis of variation in shape and optical properties of colloidal MoS2 nanostructures with temperature, explained by a nonclassical growth mechanism is presented here for the first time.

Understanding the piezoelectric response of ZnO nanotetrapods: Detailed numerical calculations

The complex tetrapod shape of zinc oxide nanostructure, which is constructed from four one-dimensional arms interconnected together via a central core, is a special 3D geometry with multifunctional applications in advanced technologies. The ZnO hexagonal wurtzite crystal lattice with a non-centrosymmetric structure introduces interesting piezoelectric property in nanorods in the bent state, which has been well reported and utilized in piezo- and tribo-electric nanogenerator applications. Considering the broad technological relevance of tetrapods, it is important to understand the piezoelectric response of zinc oxide tetrapods under different conditions. In this study, we explicate the fundamental mechanical and electrical properties of ZnO nanotetrapods (ZnO NTs) through a detailed finite element method analysis. On this basis, the effects of shape factors (including length, height, and aspect ratio) as well as connection strength and packing density on the deformation and piezoelectric potential of ZnO NTs are examined, offering guidance for the fabrication of ZnO NTs. This theoretical model and numerical simulation provide an avenue for further piezoelectric and piezotronic research of ZnO NTs.

Effect of solvent mixtures on the unique morphology for photocatalytic activity of Bi2S3 nanoparticles synthesized by microwave irradiation method

Unique morphologies of Bi2S3 nanostructures were synthesized via microwave irradiation method using two different solvents [N,Ndimethylformamide (DMF) and ethylene glycol (EG)] and two solvent mixtures [N,N dimethylformamide/water (DMF/W) and ethylene glycol/water (EG/W)]. The effect of different solvent systems on the properties of Bi2S3 samples were investigated using XRD, FESEM, EDS, XPS, UV and FTIR analysis. The XRD analysis revealed that the orthorhombic phase of increasing intensities was observed. The microscopic analysis showed that the various shapes of Bi2S3 nanostructures were obtained by changing the solvent combinations. Long nanowires and nanorods with an average length of 250 nm formed when DMF and DMF/W were used as solvents. The synthesized Bi2S3 in EG and EG/W promoted the fabrication of novel nanoflowers composed of thick nanosheets with an average breadth of 755 nm and a honeycomb shape. The EDS and XPS results confirm the purity and the presence of the Bi and S. The N2 adsorption-desorption isotherm studies revealed that the specific surface area of the Bi2S3 sample (EG/W) is 42.82 m2g-1using Brunauer-Emmett-Teller (BET). The UV-Vis absorption spectra revealed the optical properties of all Bi2S3 samples. The FTIR spectra showed the functional groups of the Bi2S3 nanostructures. Among the prepared samples, the Bi2S3 nanostructure obtained in the ethylene glycol/water exhibited the highest photocatalytic activity and achieved 95.18% degradation efficiency of methylene blue (MB) dye after 120 minutes. The MB photodegradation was determined to follow a pseudo-first-order kinetic model, with a rate constant of 0.02271 min-1 being the highest. After three cycles, the Bi2S3(EG/W) nano photocatalyst showed excellent reusability and stability.

Novel rare earth metal and aluminium codoped ZnO photocatalysts for degradation of rhodamine b dye

In this study, samarium and aluminium codoped zinc oxide nanostructures were produced via a soft chemical route, and their structural, morphological, optical, and photocatalytic capabilities were investigated. X-ray diffraction (XRD) patterns and photoluminescence (PL) studies show that both undoped and Sm &amp; Al codoped ZnO nanostructures have a hexagonal wurtzite crystal structure. The shape of the sample's hexagonal nanostructures, as seen in FESEM pictures, changes as the amount of Sm3+ doping increases. Sm3+ and Al2+ ions have been incorporated into ZnO, as seen by the EDX spectra. ZnO nanostructures were thoroughly studied to learn how Al2+ and Sm3+ doping affected their structure, shape, absorption, emission, and photocatalytic activity. The capacity to absorb visible light is enhanced by the incorporation of Sm3+ ions, which causes a red shift in the optical energy band gap from 2.5 to 3.2 eV. Based on the results of in-depth photocatalytic tests, it has been shown that Sm &amp; Al codoped ZnO nanostructures exhibit the highest photodegradation efficiency for RhB dye for Sm0.04MAl0.04MZn0.92MO, i.e. 84%, when exposed to visible light. ZnO, when doped with a rare earth metal ion (Sm3+), displays enhanced photocatalytic efficiency and might have real-world uses. In this research, nanoscale photocatalysts, as manufactured, degrade RhB dye effectively as a photocatalyst

Direct Oxidation of Hibiscus cannabinus Stalks to Vanillin Using CeO2 Nanostructure Catalysts.

Biomass lignin can be used to produce vanillin through an oxidation process. Although its purity is high, the processing time and separation efficiency are not ideal. This research aims to produce vanillin directly from Kenaf stalks without separating the lignin first from the lignocellulosic biomass. This method is greener because it does not require the separation of cellulose and hemicellulose from the biomass, thus minimizing the use of acid and alkaline solutions and saving time. A high oxygen storage capacity and release capacity of ceria as an oxidation catalyst contribute to the reversable redox properties between Ce4+ and Ce3+ in ceria lattice. Cerium oxide nanostructures were synthesized using a hydrothermal method treated under alkaline NaOH, followed by drying at 120 °C for 16 h and calcining at different temperatures between 400 and 600 °C for the direct oxidation of Kenaf stalks to vanillin under microwave irradiation. The catalysts were characterized for their physicochemical properties using XRD, N2 adsorption-desorption isotherms and TEM. All synthesized CeO2 nanostructures showed the presence of diffraction peaks assigned to the presence of cubic fluorite. The N2 adsorption-desorption isotherms showed that all catalysts possess a Type IV isotherm, indicating a mesoporous structure. The TEM image shows the uniform shape of the CeO2 nanostructures, while HRTEM images show that the CeO2 nanostructures are single-crystalline in nature. All catalysts were tested for the direct oxidation of Kenaf stalks using H2O2 as the oxidizing agent in temperatures ranging from 160 to 180 °C for 10-30 min with 0.1-0.3 g catalyst loading under 100-500 W of microwave irradiation. The CeO2-Nps-400 catalyst produced the highest vanillin yields of 3.84% and 4.32% for the direct oxidation of Kenaf stalks and extraction of lignin from Kenaf stalks, respectively. Compared to our earlier study, the highest vanillin yields of 2.90% and 3.70% for direct biomass and extracted lignin were achieved using a Ce/MgO catalyst.