Crystal Size Research Articles

Temperature‐Dependent Photoluminescence and Grain Size Control in a Prototypical Lead‐Free Bismuth Halide Perovskite

Lead‐free perovskites are non‐toxic solution‐processed semiconductors that promise applications in solar cells, light‐emitting diodes, and advanced photodetectors with broad and easily tunable spectral sensitivity. However, understanding excitonic properties and growth conditions are key for the development of efficient and stable materials. This study explores the temperature‐dependent photoluminescence (PL) and the influence of anti‐solvent on crystal size in methylammonium bismuth iodide (MA3Bi2I9), a prototypical bismuth‐based lead‐free perovskite. Using a one‐step spin‐coating method, low‐dimensional hexagonal MA3Bi2I9 crystals with controllable grain sizes ranging from 1.4 to 36 μm are developed, employing chlorobenzene as an anti‐solvent. Temperature‐dependent micro‐PL measurements reveal multi‐component PL emissions below 199 K and interestingly, below 144 K, bound excitonic recombination dominates the PL spectra. The observed free and bound exciton recombination peaks are consistent with the MA3Bi2I9 exciton binding energy of ≈340 meV reported in earlier studies. Observed temperature‐dependent PL spectra provide deeper insights into the excitonic properties of MA3Bi2I9, which have strong correlation with optoelectronic device performance, thereby providing a quick tool to assess as‐synthesized lead‐free perovskite films for defect‐site density and binding energy. Furthermore, the potential of concentration‐dependent anti‐solvent engineering in obtaining controllable bismuth perovskite crystal grain sizes for optoelectronic applications is underscored.

Temperature and pressure dependence of the fluorescence spectrum of high-pressure synthetic corundum-type Ga2O3:Cr3+, structural stability, and crystal growth under high pressure

The pressure dependence of the R1 and R2 peaks of the fluorescence spectra of high-pressure-synthesized corundum-type Ga2O3:Cr3+ was measured up to 50 GPa using a diamond anvil cell pressurized at room temperature in an argon medium. The temperature dependence of the R1 and R2 peaks was measured at low temperatures under ambient pressure from 303 to 83 K. From the measurement results, the pressure scale and low-temperature scale were determined using R1 and R2. X-ray diffraction experiments at high pressure, which were performed to confirm the effective range of the pressure scale, showed that the corundum structure undergoes a phase transition to a Rh2O3(II)-type structure at 54–65 GPa; this pressure scale is, thus, valid up to approximately 50 GPa. We also investigated the crystal growth time to optimize the crystal size of Ga2O3:Cr3+ for diamond anvil cell experiments.

The band structure and carrier recombination mechanism of α/β-phase tellurium homojunction investigated by infrared photoluminescence

During the synthesis of tellurium (Te) crystals, the coexistence of multiple crystalline phases (α-Te, β-Te, and γ-Te) with diverse structures commonly occurs, leading to instability and complexity in the performance of Te-based optoelectronic devices. This study employs physical vapor deposition to synthesize Te crystals of various sizes and morphologies, followed by spatially and temperature-dependent evaluation using Raman mapping and infrared photoluminescence (PL) spectroscopy. Spatially resolved results reveal that the size and morphology of Te crystals significantly influence the energy and peak profiles of Raman and PL spectra. Statistical analysis of spatially random sampling indicates the PL peak energies of Te crystals follow a lognormal distribution in terms of their occurrence frequencies, reflecting the complex interplay of multiple factors during crystal growth. This results in the coexistence of α-Te and β-Te phases, forming α/β-Te heterophase homojunction (HPHJ). Meanwhile, temperature-dependent PL results, obtained for the range of 3–290 K, reveal multi-peak competitive behavior in the PL spectra, accompanied by S-shaped shifts in peak energy. These features can be rationally explained by an interface transition-recombination mechanism based on the I-type α/β-Te HPHJ model. It also confirms infrared PL spectroscopy is an effective method for identifying the crystalline phase composition of Te crystals.

Effect of Amino Acids on the Synthesis of NiFe2O4/Au Hybrid Nanoparticles

Hybrid nanoparticles, composed of magnetic oxides and gold, have garnered significant interest due to their potential applications in various fields, including catalysis, diagnostics, and nanomedicine. In this study, the effect of reaction parameters on the reduction of HAuCl4 by different non-sulfur amino acids (glycine, L-serine, L-tryptophan, and L-tyrosine) was determined using the design of experiment (DOE) method. The results of the analysis of the regression equations were used to select the conditions and develop a methodology for the preparation of the hybrid magnetic NiFe2O4/Au nanoparticles (NPs) by direct reduction of gold on the magnetic surface using the aforementioned amino acids as the reducing and stabilizing agents simultaneously. The materials were characterized using XRD, TEM, XPS, and Vis/FTIR spectroscopy. The results indicate the successful synthesis of magnetic NiFe2O4/Au nanoparticles with all amino acids used, but the size of the gold crystals, their surface density, and the details of the NP structure (inlaid or a core–shell structure) depend on the amino acid used. The mechanism of the gold deposition on the magnetic core surface and the difference in the effect of various amino acids are discussed. The developed synthesis strategy can be extended to other metal ferrites and iron oxides.

Influence of the Sodium Titanate Crystal Size of Biomimetic Dental Implants on Osteoblastic Behavior: An In Vitro Study

Treating the surfaces of dental implants in an alkaline medium allows us to obtain microstructures of sodium titanate crystals that favor the appearance of apatite in the physiological environment, producing osteoconductive surfaces. In this research, 385 discs made of titanium used in dental implants underwent different NaOH treatments with a 6M concentration at 600 °C and cooling rates of 20, 50, 75, and 115 °C/h. Using high-resolution electron microscopy, the microstructures were observed, and the different crystal sizes were determined and compared with control samples (those without biomimetic treatment). Roughness, wettability, surface energy and the sodium content of the surface were determined. The different surfaces were cultured with human osteoblastic cells; cell adhesion was determined at 3 and 14 days, and the degree of mineralization was determined at 14 days via alkaline phosphatase levels. Variations in the microstructure and size of sodium titanate crystals in NaOH solutions rich (1 g/L) or low in calcium (approximately 100 ppm) were determined. The results show that as the cooling rate increases, the size of the crystals decreases (from 0.4 μm to 0.8 μm) except for the case of 115 °C/h, when the rate is too fast for crystalline nucleation to occur on the surface of the titanium. The thermochemical treatment does not influence the roughness or the cooling rate since a Sa of 0.21 μm is maintained. However, the presence of titanate causes a decrease in the contact angle from 70° to 42° and, in turn, causes an increase in the total surface energy from 35 to 49.5 mJ/m2, with the polar component standing out in this energy increase. No variations were observed in the thermochemical treatments in the presence of sodium, which was around 1200 ppm. It was observed that as the size of the crystals decreases, cell adhesion increases at 3 days and decreases at 14 days. This is because finer crystals on the surface are already in the mineralization process, as demonstrated using the level of alkaline phosphatase that is maximal for the cooling rate of 75 °C/h. It was possible to confirm that the variations in the concentrated NaOH solutions with different calcium contents did not affect the crystal sizes or the microstructure of the surface. This research makes it possible to obtain dental implants with different mineralization speeds depending on the cooling rate applied.

Development of Fe/SiBr/Si₃N₄/silica fume nanocomposites from recycled metal waste for industrial applications

Due to the high cost of raw materials, this work aims to benefit from metal waste, especially iron (Fe) and silicon bronze, which results from turning workshops and recycling them to obtain nanocomposites for industrial applications. In this respect, Fe/SiBr/Si3N4/silica fume nanocomposites possessing superior mechanical, wear, and magnetic characteristics have been produced using powder metallurgy (PM) technology. Milled sample particle size, crystal size, and phase composition were investigated using X-ray diffraction (XRD) technique and transmission electron microscopy (TEM). The powders were compressed and sintered in argon to get excellent sinterability. The sintered nanocomposites’ physical, mechanical, wear, electrical, and magnetic properties were investigated. The microstructure was also examined using field emission scanning electron microscopy (FESEM). The results showed a noticeable decrease in the size of particles and crystallite size after adding reinforcements, reaching 22 nm for the sample improved with 5 vol% silica fume and 5 vol% Si3N4 (FS4). In addition, after adding reinforcements, there was a clear improvement in the microhardness, Young’s modulus, and wear rate of Fe-SiBr, reaching 58, 27.89, and 43.21% percent for the sample FS4. Adding reinforcements harms the electrical conductivity of Fe-SiBr, as it decreases to 8.64 × 106 S/m for the same previous sample. Finally, adding reinforcements slightly affects the decrease in magnetization of the nanocomposites.

Synthesis and Characterization of Brucine Gold Nanoparticles for Targeted Breast Cancer Therapy: Mechanistic Insights Into Apoptosis and Antioxidant Disruption in MCF-7 Cells.

Globally, breast cancer continues to be the leading type of cancer affecting women, with rising mortality rates projected by 2030. This highlights the importance of developing new, affordable treatments, like drug delivery systems that use nanoparticles. Gold nanoparticles (AuNPs), including their exceptional optical and physical attributes, make them an attractive vehicle for targeted treatment, allowing for accurate and focused delivery of medication directly to cancerous cells while reducing harmful side effect. This study focuses on the synthesis and characterization of brucine-gold nanoparticles (BRU-AuNPs) for targeted breast cancer therapy by evaluating their antioxidant and apoptotic mechanism. BRU-AuNPs were synthesized and characterized (UV-Vis spectroscopy, Fourier transform infrared [FTIR], scanning electron microscopy [SEM], x-ray diffraction [XRD], dynamic light scattering [DLS], and zeta potential) to confirm successful synthesis, size, and stability. Invitro studies were assessed using MCF-7 breast cancer cell lines to evaluate cell cytotoxicity, antioxidant balance, reactive oxygen species (ROS) generation, mitochondrial membrane potential, apoptosis induction, cell migration, and pro-apoptotic gene expression. Characterization results confirmed the successful synthesis of BRU-AuNPs with an average crystal size of 85.40nm and stable surface charge. Results demonstrated that BRU-AuNPs reduced MCF-7 cell viability in a dose-dependent manner, with an IC50 value of 11.47µg/mL. Treatment with BRU-AuNPs altered the antioxidant balance, increased ROS generation, depolarized mitochondrial membranes, and induced apoptosis. Additionally, BRU-AuNPs inhibited cell migration and upregulated pro-apoptotic gene expression. The synthesized BRU-AuNPs exhibit potential as a highly effective targeted delivery system for breast cancer treatment. Their ability to directly deliver BRU to tumor cells while reducing side effects and enhancing therapeutic efficacy underscores their promise in advancing breast cancer therapy. Further studies are warranted to explore their clinical potential and optimize therapeutic outcomes.

Preparation and Thermal Performance Study of a Novel Organic-Inorganic Eutectic Phase Change Material Based on Sodium Acetate Trihydrate and Polyethylene Glycol for Heat Recovery.

A novel organic-inorganic eutectic phase change material (PCM) based on sodium acetate trihydrate (SAT) and polyethylene glycol (PEG) was developed to meet the needs of heat recovery and building heating. Three kinds of PEG with different molecular weights were selected to form organic-inorganic eutectic PCM with SAT. The thermal properties of three series of SAT-PEG eutectic PCM were compared based on DSC results, focusing on the impact of PEG addition on the phase change temperature and enthalpy of SAT, as well as the melting uniformity. The inhibitory effects of two nucleating agents on the supercooling of SAT-PEG eutectic PCM were systematically investigated. The effect of PEG on the crystallization behavior of SAT was studied using a metallographic microscope. To evaluate the thermal reliability of the SAT-PEG eutectic PCM, 600 cycles of melting-solidification experiments were conducted. Experimental results show that SAT can form eutectic PCMs with PEG200, PEG600, and PEG6000, respectively, with high enthalpy and excellent melting uniformity. The phase change temperature ranged from 55 °C to 60 °C and the enthalpy was as high as 250-280 kJ/kg. The results of the cooling curves show that 10 wt% tetrasodium pyrophosphate decahydrate (TPD) can reduce the supercooling degree to less than 1 °C. Significantly, all three series of SAT-PEG eutectic PCMs exhibit exceptional thermal reliability after 600 cycles of melting-solidification, with shifts in the phase change temperatures and enthalpies of less than 4%. XRD diffraction patterns showed that SAT, PEG, and TPD were physically mixed without a chemical reaction to form new substances. Microscopic images reveal that the addition of PEG preserves the original needle-shaped crystal morphology of SAT while reducing its crystal size. The rapid formation of small crystals can provide more nucleation points and expedite crystallization, thereby enhancing the heat release capabilities of the PCM.

Multifunctional Organic Molecule for Defect Passivation of Perovskite for High-Performance Indoor Solar Cells.

Perovskite solar cells (PSCs) can utilize the residual photons from indoor light and continuously supplement the energy supply for low-power electron devices, thereby showing the great potential for sustainable energy ecosystems. However, the solution-processed perovskites suffer from serious defect stacking within crystal lattices, compromising the low-light efficiency and operational stability. In this study, we designed a multifunctional organometallic salt named sodium sulfanilate (4-ABS), containing both electron-donating amine and sulfonic acid groups to effectively passivate the positively-charged defects, like under-coordinated Pb ions and iodine vacancies. The strong chemical coordination of 4-ABS with the octahedra framework can further regulate the crystallization kinetics of perovskite, facilitating the enlarged crystal sizes with mitigated grain boundaries within films. The synergistic optimization effects on trap suppression and crystallization modulation upon 4-ABS addition can reduce energy loss and mitigate ionic migration under low-light conditions. As a result, the optimized device demonstrated an improved power conversion efficiency from 22.48% to 24.34% and achieved an impressive efficiency of 41.11% under 1000 lux weak light conditions. This research provides an effective defect modulation strategy for synergistically boosting the device efficiency under standard and weak light irradiations.

Tailoring Structural, Microstructural, Dielectric and Gas Sensing Properties of SnO2 Nanoparticles: Size Matters

This manuscript reports on the characteristics of SnO2 nanoparticles (NPs) prepared using the conventional sol-gel technique and showcases the effect of calcination temperature on crystal structure, size, and gas-sensing properties. Rietveld refinement of diffraction profiles of SnO2 NPs calcined at 400 °C [SnO2@400] and 600 °C [SnO2@600] showed that both the samples possess tetragonal phase having space group P 4 / 2 mnm . FESEM microimages of SnO2@400 and SnO2@600 were subjected to morphological analysis using an image processing method. The results showed that the grains exhibited swelling as the calcination temperature increased as per the Ostwald ripening process. High-resolution transmission electron microscopic (HRTEM) image depicted (110) lattice plane orientation with d = 0.34 nm consistent with XRD studies. Thus, the dielectric constant ε ′ was increased from 38 to 56 as the temperature rose to 600 °C from 400 °C. Simultaneously, electrical resistance increased from 0.77 × 106 Ω to 1.27 × 106 Ω with rise in the calcination temperature of SnO2 NPs from 400 °C to 600 °C. The investigation on sensing acetone gas revealed that the SnO2@600 sample possessed the maximum sensing response along with a shorter recovery time compared with SnO2@400.

Pirfenidone microcrystals for pulmonary delivery: Regulation of the precipitation behavior in the supercooled droplet.

Pirfenidone (PFD) is one of the first-line drugs for treating idiopathic pulmonary fibrosis, while directly delivering PFD to lung showed better efficiency. However, PFD is a non-glass former and easily precipitates into larger-sized crystals that are undesirable for pulmonary delivery. Hence, the fabrication of PFD particles with pulmonary delivery efficiency remains challenging. Herein, a series of particles were prepared by spray freeze drying a PFD and leucine mixed solution. The sub-ambient behavior of the mixed solution was evaluated via a differential scanning calorimeter. The effects of the PFD/leucine mass ratio and freezing temperature on the particle morphology, size, crystal polymorphism, molecular structure and in vitro aerosol performance were investigated. Shortening the lifetime of the droplet and adding proper amounts of leucine are the keys to decreasing the PFD crystal size and improving its dispersity. The optimal sample is SF-80D-P95L5-2, with high FPF and eFPF values of∼65.97% and∼27.86%, and owing to its high drug loading (95%), the FPD and eFPD are extremely high at∼6.27mg and∼2.65mg, respectively, equivalent to∼6.27mg and∼2.65mg PFD deposited in the lungs and alveoli, respectively, when 10mg dry powder is inhaled. This work provides a potential strategy for tuning the precipitation behavior of PFD microcrystals with high pulmonary drug delivery efficiency.

Anchorage of ZnO quantum dots and CuO on graphene for sonophotocatalytic treatment of pharmaceutical effluent: From experimental data and prediction by advanced machine learning algorithms

Quantum dots (QDs) have recently received much attention as photocatalysts due to their unique properties. Despite the advantages reported for QDs as photocatalysts in literature, their sonophotocatalytic/photocatalytic activity is still hindered by a series of barriers, which limit them to operate after several successive cycles efficiently. The main aim of this work is to fabricate an efficient and recyclable sonophotocatalyst/photocatalyst using ZnO quantum dots (ZQDs), tenorite (CuO), and graphene (G). In this regard, different amounts of ZQDs (ZQDs(x)/G, x= 10, 20, 30, 40, and 50mg) were immobilized on graphene by hydrothermal method and various weight percent of CuO was impregnated on ZQDs(40)/G. The PXRD patterns and Raman spectra confirmed the wurtzite and monoclinic crystal structure for ZQDs and CuO, respectively. Also, FESEM, AFM, and PXRD showed that the mean crystal size of ZQDs increased after immobilization on graphene and impregnation by CuO. PL and Mott–Schottky analyses showed that the presence of GO and CuO in CuO(0.5)/ZQDs(40)/G reduced the recombination of excitons and formed p-n heterogeneous junctions between CuO and ZnO. The VB and CB potential and bandgap energy were obtained using DRS and Mott–Schottky analyses, and the mechanism of tetracycline (TC) degradation was proposed according to active species trapping and H2O2 paper testes. The apparent rate constant (kapp) was 0.030 and 0.060min-1 for photocatalytic and sonophotocatalytic degradation of TC in the presence of CuO(0.5)/ZQDs(40)/G, respectively. The treated effluent of TC showed acceptable performance in growing wheat seeds. The electricity cost estimation showed that (CuO(0.5)/ZQDs(40)/G) consumed less electricity in sonophotocatalytic/photocatalytic TC degradation and could also be used in several successive cycles. Finally, two RF and AdaBoost models based on ML algorithms were developed to predict photocatalytic/sonophotocatalytic degradation. The results showed that the values of statistical metrics, including SAE, MAE, MSE, and RMSE, for the AdaBoost model were relatively lower than those for the RF model, indicating better prediction performance in train and test datasets.

Surfactants govern the fabrication of sulfur-enriched heterojunction catalysts for highly selective photocatalytic conversion of toluene

Photocatalytic selective oxidation of toluene represents a milder and more environmentally friendly strategy for the synthesis of benzaldehyde. In order to enhance catalytic performance, efficient carrier separation and transport are crucial in the photocatalytic process. This study focused on the preparation of ZnS@ZnIn2S4 with sulfur vacancies and heterostructures, combining the advantages properties of ZnS and ZnIn2S4 in photocatalysis. The effects of ZnS and surfactants on the catalytic properties of the composites were studied in depth. Characterization tests revealed that surfactant-modified ZnS@ZnIn2S4 exhibited a higher concentration of sulfur defects, which facilitated electron trapping and promoted photogenerated carrier separation and utilization. Additionally, the present study also demonstrated that the incorporation of ZnS and surfactants could reduce the crystal size of ZnIn2S4, thereby facilitating the exposure of additional active sites. The synergistic effect of the aforementioned advantages enabled toluene to undergo oxidation at a conversion rate of 39% in the presence of oxygen, resulting in the production of benzaldehyde with an exceptional selectivity of 92%. This finding offers valuable insights for future endeavors in designing photocatalytic C-H bond oxidation catalysts.

Bioinspired Synthesis of Silver Nanoparticles Using L. Reuteri: Antibacterial Efficacy, Molecular Docking Insights, and Cytotoxicity Assessment

AbstractThis study reports the green synthesis of silver nanoparticles (AgNps) by using Lactobacillus reuteri. Characterized AgNps exhibited near‐spherical morphology with an average size of 86.54 nm, as revealed by SEM (scanning electron microscopy), TEM (transmission electron microscopy), and AFM (atomic force microscopy) analyses. The nanoparticles displayed a slightly rough surface, with some particles exhibiting surface protrusions and sharp edges. The zeta potential measurement of −30.16 mV and electrophoretic mobility of −2.36 cm2/Vs that indicated the presence of negatively charged functional groups on the AgNps surface, suggesting stabilizing biomolecules that prevent nanoparticle aggregation in solution. The hydrodynamic size of the AgNps was determined to be 140.3 nm, and XRD (X‐ray diffraction) analysis revealed a crystallinity of 76.89% with an average crystal size of 8.35 nm and an interplanar distance of 0.233 nm. AgNps demonstrated crystallinity and potent antibacterial activity against Pseudomonas aeruginosa (92.9% killing efficiency) and an ATCC reference strain (76.8%). Molecular docking revealed moderate interactions between an optimized Ag3 cluster and key amino acid residues (Arg277, Gln279, Trp280, Asp273, and Val276) in the P. aeruginosa protein. These interactions, with binding energies ranging from −1.89 to −3.68 kcal/mol, suggested a potential mechanism for the observed antibacterial activity. A charge transfer interaction involving Asp273, contributing a stabilization energy of 3.66 kcal/mol, was identified as a key factor in the Ag‐protein complex formation.

Crystal size effect on large deformation mechanisms of thermoplastic polyurethane

Crystal size effect on large deformation mechanisms of thermoplastic polyurethane

The Origin of Synergetic Effect in Mixed Mn-Co Oxide with Spinel Structure for Catalytic Oxidation of CO

In this work, the origin of the synergetic effect in mixed MnxCo3-xO4 oxides with the spinel structure in the CO oxidation reaction was tested. A series of MnxCo3-x oxide catalysts were synthesized by the coprecipitation method with further calcination at 600 °C and varying manganese content from x = 0 to x = 3. The catalysts were characterized using XRD, TEM, N2 adsorption, TPR, EXAFS, and XPS. The catalytic activity of MnxCo3-x oxide catalysts was tested in CO oxidation reactions. The addition of manganese to cobalt oxide results in the formation of mixed Mn-Co oxides based on a cubic or tetragonal spinel structure, a change in microstructural properties, such as surface area and crystal size, as well as local distortions and a decrease in the surface concentration of Co ions and Co in the octahedral sites in spinel structure; it also decreases catalyst reducibility. For all catalysts, the activity of CO oxidation decreases as follows: Mn0.1Co2.9 > Co3O4~Mn0.3Co2.7 > Mn0.5Co2.5 > MnOx > Mn0.7Co2.3 > Mn0.9Co2.1~Mn1.1Co1.9~Mn2.5Co0.5 > Mn2.9Co0.1 > Mn1.7Co1.3 > Mn2.1Co0.9 > Mn1.3Co1.7~Mn1.5Co1.5~Mn2.3Co0.7. The Mn0.1Co2.9 catalyst displays the best catalytic activity, which is attributed to its small crystal size and the maximum surface ratio between Co3+ and Co2+. A further increase in the manganese content (x > 0.3) provokes drastic changes in the catalytic properties due to a decrease in the cobalt content on the surface and in the volume of mixed oxide, changes in the oxidation states of cations, and structure transformation.

Effect of Chemical Treatment on the Physicochemical and Mechanical Properties of Sansevieria ehrenbergii (SE) Leaf Fibers and Their Utilization in Textiles

ABSTRACT Natural fibers are gaining significant attention in minimizing the usage of non-ecofriendly fibers in various industrial applications. In the present study, fibers extracted from the leaves of the Sansevieria ehrenbergii (SE) plant were investigated as potential sources of cellulosic fibers for textile applications. The water-extracted fibers were alkali-treated using varying treatment parameters, and their properties were then characterized using X-ray diffractometry, Fourier Transform Infrared spectroscopy, and Thermogravimetric analyzer. The optimal treatment parameters were found to be 15 g/L NaOH, 90°C temperature, and 60 min. The obtained average length (980 mm), fineness (31.3 Tex), moisture regain (10.6%), and moisture content (9.6%) values were comparable to other fibers. Tensile strength values for untreated and treated fibers were 470.7 MPa and 582 MPa, respectively, while the elongations at break were 5.8% and 6.3%, respectively. The treated SE fibers contained 75.3%, 8.6%, and 5.8% of cellulose, hemicelluloses, and lignin, respectively. In addition, the crystallinity index and crystal size of the treated SE fiber were 74.6% and 0.79 nm, respectively. Moreover, alkali treatment was found to enhance the thermal stabilities of the fibers. These findings suggest that the SE plant is a potential source of cellulosic fibers for various textile products.

Removal of artificial anionic dye by electrocoagulation and electro-oxidation combined system using aluminum and nano (Cu-Mn-Ni) composite electrodes

The combined system of electrocoagulation (EC) and electro-oxidation (EO) is one of the most promising methods in dye removal. In this work, a solution of 200 mg/l of Congo red was used to examine the removal of anionic dye using an EC-EO system with three stainless steel electrodes as the auxiliary electrodes and an aluminum electrode as anode for the EC process, Cu-Mn-Ni Nanocomposite as anode for the EO process. This composite oxide was simultaneously synthesized by anodic and cathodic deposition of Cu (NO3)2, MnCl2, and Ni (NO3)2 salts with 0.075 M as concentrations of each salt with a fixed molar ratio (1:1:1) at a constant current density of 25 mA/cm2. The characteristics structure and surface morphology of the deposited nano oxides onto the graphite substrates were determined by (XRD), (FE-SEM), (AFM), and (EDX). The results shown that nano Cu-Mn-Ni oxides were successfully deposited onto the anode and cathode. The crystal size and root mean square for the cathode were 30.79 nm and 79.36 nm, respectively, while for the anode, they were 24.19 nm and 41.88 nm, respectively. Furthermore, the combined system was examined for C.D, NaCl concentration, and time. In the EC-EO combined system, the cathode and anode were efficient when used as anodes for the EO process, besides aluminum. The cathode was more effective in the removal process than the anode due to its larger crystal size and the rough, granular shape of its surface. When current density (C.D) increased from 3 to 6 mA/cm², the removal efficiency shifted from 95% to 98%. However, excellent removal of 98% and 96.5% was attained with 1.665 and 2.0859 kWh/kg of dye as energy consumption in the presence and absence of NaCl salt, respectively by applying 6 mA/cm2 within 20 min of electrolysis.

A novel approach revolutionizing ZnO nanoparticle synthesis with CTAB surfactant and Spirulina palenthesis microalgae for enhanced antimicrobial performance

Zinc Oxide Nanoparticles (ZnO NPs) are highly efficient photocatalysts, applied in areas such as self-cleaning, antimicrobial protection, UV-blocking, and anti-fogging. Their photocatalytic performance depends on factors like size, shape, and surface area, which can be controlled through morphology. In this study, Cetyltrimethyl Ammonium Bromide (CTAB) was used as a template to design ZnO nanorods, with Spirulina plantesis acting as a capping agent to ensure uniform size distribution. CTAB, a cationic surfactant, reduces surface tension, enabling more even dispersion of ZnO particles in a sol-gel medium, as observed through SEM imaging. The study focused on modifying ZnO morphology by adjusting the CTAB molar ratio (10%, 20%, and 30%) to the Zn(NO3)2 precursor. Characterization techniques such as TGA-DTA, FT-IR, XRD, BET/BJH, UV-VIS-DRS, and SEM were employed. Results showed that CTAB significantly reduced ZnO crystal size, improving particle homogeneity, with average sizes of 30.7, 29.8, and 27.6 nm, compared to 32.5 nm without CTAB. XRD analysis confirmed the ZnO phase with a P63mc space group (a = b = 3.25254 Å, c = 5.2110 Å, α = β = 90°, γ = 120°). The most enhanced photocatalytic activity was observed in the ZnO-CTAB-20 formulation, particularly in antibacterial tests against Staphylococcus epidermidis and Pseudomonas aeruginosa.

Effect of Am-241 Irradiation on ZnO Crystallinity with Different Annealing Temperature

Am-241 is an alpha emitting isotope which can be used to fuel a nuclear battery via alphavoltaic effect by using a semiconductor to convert alpha radiation to electricity. The main issue of alphavoltaic battery is the radiation damage due to high energy alpha particle, resulted in a rapid decline in performance. Zinc oxide (ZnO) is known as a semiconductor with high radiation tolerance. In this study, the effect of annealing temperature to ZnO crystal was studied along with its alteration due to Am-241 irradiation overtime. The annealing temperatures were set at 450°C and 650°C. The irradiation process was carried out using Am-241 isotope for 12 days with an activity of 44.85 mCi and approximately 0.0866 MGy of absorbed dose. The crystal structure of fabricated and irradiated ZnO were investigated through X-ray Diffraction (XRD). The XRD diffraction pattern indicates that the crystal structure of ZnO is hexagonal wurtzite and still maintained after irradiation process. Raising the annealing temperature from 450°C to 650°C leads to a reduction in peak intensity. This change correlates with an increase in grain size post-irradiation. After exposure to alpha particle radiation, changes occurred in the diffraction peaks of ZnO. At 450°C annealing temperature, the intensity decreased by 94.822%, while at 650°C annealing temperature, the intensity decrease was 85.489%. This shows that increasing the annealing temperature can reduce the decrease in intensity after irradiation with alpha particles. The (002) plane shifted by 0.057˚ at 450°C annealing temperature and by 0.042˚ at 650°C after irradiation. In addition, the crystal lattice parameters increased after irradiation, which led to a change in the FWHM value and an increase in the crystal grain size.