Surface Morphology Research Articles

Optimization of Ti2O3 thin films by magnetron sputtering and study of their photoelectric performance

AbstractAbstractIn this study, Ti2O3 thin films were successfully produced using magnetron sputtering. Through orthogonal gradient experiments, the impact of substrate temperature, sputtering vacuum, RF power, and sputtering duration on surface morphology, roughness, physical structure, and resistivity was investigated. Various analytical techniques were employed, including AFM and SEM for surface morphology observation, XRD and Raman for qualitative physical structure analysis, XPS for elemental valence examination, and the four‐probe method for resistivity measurements. The study identified optimal growth conditions for Ti2O3 films, demonstrating a low resistivity of 2.66 × 10−3 Ω cm under the following conditions: RF power of 200 W, sputtering vacuum of .6 Pa, substrate temperature of 600°C, and sputtering duration of 60 min. Additionally, the sensor arrays were efficiently fabricated using the Lift‐off method to evaluate the photoelectric performance of the films. A light responsiveness of approximately 6 µA/W was observed in the device when illuminated with 950 nm light for 10 s. This finding carries important implications for the use of Ti2O3 thin films in future photoelectric devices.

High‐temperature oxidation of Cu–Al–Ni–Mn shape‐memory alloy

AbstractThe isothermal oxidation behavior of the Cu‐11.35Al‐3.2Ni‐3.5Mn (wt.%) shape‐memory alloy (SMA) in the temperature range of 500–900°C in oxygen was studied using the thermogravimetric (TG) method. TG curve showed that the alloy has parabolic isothermal oxidation characteristics. The effect of oxidation on the surface morphology and chemical composition of the Cu–Al–Ni–Mn alloy was determined by scanning electron microscopy, energy‐dispersive spectroscopy, and X‐ray photoelectron spectroscopy (XPS) analyses. The oxidation rate of SMA increases up to 700°C, remains stable at 800°C, and increases again up to 900°C. The XPS analysis identified that the corrosion products mainly contained MnO2, MnO/Mn2O3, and Al2O3.

A review on the current status of dye‐sensitized solar cells: Toward sustainable energy

AbstractDye‐sensitized solar cells (DSSCs) are among the most attractive third‐generation photovoltaic technologies due to their low toxicity, versatility, roll‐to‐roll compatibility, ultralightness, and attractive power conversion efficiencies (PCEs). However, their transition from the laboratory scale to the industrial scale has been slow due to their inability to compete with silicon‐based cells in terms of efficiencies and stabilities. Research activities on DSSCs have been ongoing for several decades to improve the efficiency and cost‐effectiveness of photovoltaics but these attempts are still inadequate. Their chemical and physical properties must be refined to increase efficiency and commercialization. This review provides a concise overview of the recent advances taking place in the DSSCs research field, including molecular engineering technologies, the quest for superior carrier transport materials (CTMs), efficient sensitizers, and better electrodes. Also, this review compiles knowledge of the historical development of DSSCs, the current advancements such as control of surface morphologies, doping strategies, modeling and simulation, characterization, and recent cutting‐edge research happenings in photovoltaic research. Finally, nanostructured materials that have been used as photoelectrodes and the practical applications of DSSCs in internet of things (IoT) and portable electronics are examined to identify challenges and future advancements. The main aim of this work is to be a pathfinder for scientific researchers in this field exploring various energy harvesting materials and optimization strategies of different components of DSSCs.

Enhanced Physio‐Chemical Properties of PMMA/PS Polymer Blends by DC Glow Discharge Plasma Treated K2TI6O13 for Electronic Applications

AbstractCeramic filler modified polymer blends are more in demand due to their excellent compatibility, easy processing and cost‐effectiveness. In the present work, we modified Polymethyl methacrylate (PMMA)/Polystyrene (PS) blends using solution blending with untreated (UT) and DC glow discharge plasma‐treated (air plasma treated‐APT) potassium hexatitanate (K2Ti6O13). Chemical bonding of virgin and modified blends was confirmed by Fourier transform infrared spectrophotometer (FTIR). Decreased structural defects and imperfections of KTO were confirmed by Raman spectroscopy. Modified surface morphology and elemental analysis were detected by scanning electron microscopy (SEM) and energy‐dispersive X‐ray analysis (EDAX). The quantification of particle size distribution has been determined by Zetasizer. Increased degree of crystallinity and decreased average crystallite size after plasma treatment were determined by X‐ray diffraction. Increased dielectric constant from ~22–200 and decreased loss up to 0.7 were analyzed by impedance analyzer. Lee's disc probe was deployed to confirm the optimized thermal conductivity of the modified blend system. By Differential Scanning Calorimetry, glass transition temperature of modified polymer blends was investigated. The change in surface from hydrophobic to hydrophilic by plasma exposure was confirmed by surface goniometer. However, the enhanced dielectric performance of modified PMMA/PS/KTO polymer blends may be suitable for flexible energy storage devices and gadgets.

Electric and dielectric responses of Au/n-Si structure by Mn doped PVC interfacial layers

This paper has investigated and compared the impact of polyvinyl chloride (PVC) without/with manganese (Mn) metallic nanoparticles interfacial layer on the electric and impedance characteristics of Schottky diode (SD) with a structure of Au/n-Si (MS). The structures of these two metal-polymer-semiconductor (MPS) SDs are Au/PVC/n-Si and Au/PVC:Mn/n-Si. A detailed description of the SDs manufacturing process is given. The x-ray diffraction (XRD) analysis, Scanning Electron Microscope (FE-SEM) images, and Electron Dispersive x-ray (EDX) spectroscopy are three methods that have been utilized to examine mean size of crystallite, morphology of surface, purity specification. The fundamental electronic variables of these devices are ascertained and contrasted with one another using the I-V characteristic measurement at ±6 V. Ohm’s law, Thermionic Emission (TE) theory, modified Norde, and Cheung functions are used to calculate the SDs’ leakage current (I0), ideality coefficient (n), potential barrier height (BH), shunt (Rsh), and series (Rs) resistances. Investigations are conducted on the energy dependence of surface states density (Nss) and the current conduction mechanisms (CCMs) for both reverse and forward biases. These interfacial layers are known to decrease the n, Rs, and Nss. The PVC polymer interlayer leads to improve the efficiency of the MS-type SD, but it does not when doped by Mn nanoparticles. Additionally, by measuring impedance at a bias of 1.5 V and 100 Hz-1 MHz frequency range, the frequency dependence of dielectric properties of the prepared SDs is studied. The dielectric permittivity, dielectric loss tangent, electronic modulus, and ac electronic conductivity of these SDs are all studied.

The time evolution of electrical and thermodynamic characteristics of surface dielectric barrier discharge caused by dielectric degradation

Abstract The degradation of the dielectric layer is a common issue in dielectric barrier discharge (DBD). The performance of DBD devices may suffer from instability due to potential corrosion of the dielectric layer caused by discharge, which could even result in structural failure. To gain a comprehensive understanding of the degradation of DBD devices during discharge, the evolution of the performance of DBD devices with various dielectric materials over time is studied. Periodic patterns are found to form on the dielectric surface along the edge of the high-voltage electrode. The electrical data, emission spectra, and surface morphologies of DBD devices with three different dielectric materials, namely ceramics, glass, and PCB, are obtained during an eight-hour discharge. The electrical and thermodynamic characteristics of DBD devices with the three dielectric materials are found to initially decrease by about 20~40%. Subsequently, they remain stable in devices with ceramics and PCB dielectric layers but increase in devices with glass dielectric layers until the end. Surface morphologies reveal that periodic patterns consisting of metal accumulations, etching pits, and metal depositions form on the surfaces of ceramics, glass, and PCBs, respectively. Some organic compounds vaporize from the surface of PCBs. The deposition, etching, and vaporization could be reasons for changes in the electrical and thermodynamic characteristics. It shows that degradation occurs not only in organic dielectrics like polymers but also in inorganic dielectrics such as ceramics and glass. To enhance stability and prevent potential failures and overestimations, electrical and optical measurements could be utilized as diagnostic methods in applications involving DBD devices.


Ultrasonic assisted green synthesis of CuO nanoparticles: a real catalytic and antimicrobial agent

ABSTRACT This study reported facile biosynthesis of CuO nanoparticles employing leaf extract of Prosopis glandulosa as a stabilising agent by modest ultrasonic assisted technique. The synthesised nanoparticles were characterised via greatly refined systems comprising UV-visible, FTIR, XRD, SEM EDX, Zeta sizer, and Zeta potential. These facilities triggered the study of optical, functionality, crystallinity, surface morphology, elemental composition, and surface potential of the synthesised nanoparticles. The SEM and FT-IR analysis confirmed the semi-spherical shapes and functionalities of the synthesised NPs respectively. The zeta size and zeta potential of CuO NPs were established to be 65 nm and −1.42 mV respectively. The resultant NPs were applied as an efficient antimicrobial and catalytic candidate for the successful degradation of Eriochrome Black T (EBT) dye. Various factors were optimised such as dose, time, and NaBH4 concentration to achieve maximum catalytic efficiency of CuO nanoparticles. The NPs show excellent catalytic performance of about 92% degradation of EBT within 30 minutes. The antimicrobial performance was also tested by varying the concentration of NPs (250, 500, 1000, and 2000 g/mL via disc diffusion protocol. The results show that CuO NPs have excellent antibacterial activity alongside E. coli at MIC values of 250 g/mL as equated to S. areas and Aspergillus niger.

3D Nickel–Manganese bimetallic electrocatalysts for an enhanced hydrogen evolution reaction performance in simulated seawater/alkaline natural seawater

In this paper, we report an inexpensive one-step synthesis of self-supported 3D nickel-manganese (NiMn) bimetallic coatings and their application for the hydrogen evolution reaction in simulated seawater (1 M KOH + 0.5 M NaCl) and alkaline natural seawater (1 M KOH + natural seawater). These binary coatings were electrodeposited on a titanium substrate using a facile electrochemical deposition method by a dynamic hydrogen bubble template technique. The as-deposited NiMn coatings with variable Mn amounts produce typical globular and unique porous architecture with abundant pores of different sizes. The activity of these fabricated catalysts towards the hydrogen evolution reaction was investigated by linear sweep voltammetry towards simulated seawater and alkaline natural seawater at different temperatures. The surface morphology and composition of the catalysts were also characterized by scanning electron microscopy and inductively coupled plasma optical emission spectroscopy. The as-prepared NiMn/Ti electrocatalyst, which was electrodeposited using a chemical bath containing Ni2+ and Mn2+ ions with a molar ratio of Ni2+:Mn2+ = 1:5, exhibits excellent hydrogen evolution activity in simulated seawater with an ultra-low overpotential of 64.2 mV to reach a current density of 10 mA cm−2. It is noteworthy that this NiMn/Ti electrocatalyst also achieves a current density of 10 mA cm−2 in alkaline natural seawater with a comparably low overpotential of 79.3 mV. The current densities increase by ca. 1.75–2.35 times with an increase in temperature from 25 °C to 75 °C for hydrogen evolution in both electrolytes. This bimetallic catalyst has shown excellent long-term stability at a constant potential of −0.23 V (vs. RHE) and a constant current density of 10 mA cm−2 for 10 h, which ensures higher durability and robustness for practical application of seawater splitting technology.

Forecasting chaotic behavior of the drill bit in real-time using a DNN model integrated with rock surface morphology

The multiple regenerative effects during the drilling process cause the drilling system to exhibit complex motions, even leading to chaotic behavior. Additionally, due to the inability to obtain real-time rock parameters, traditional drilling dynamics models and time-series forecasting models cannot accurately forecast the real-time operational status of the drilling system. In this paper, a deep neural network (DNN) model integrated with rock surface morphology model is proposed to forecast the real-time operational status of the drill bit. This new model can permanently record the changes in rock surface morphology and multiple regenerative effects during the drilling process, enhancing the perception of rock parameters and improving the forecasting accuracy of the drill bit’s operational status. Experimental results show that the new model forecasts the drill bit’s operational status with higher accuracy compared to other typical time-series forecasting models without integrating surface morphology model. Furthermore, this new model demonstrates superior convergence speed, stability, and generalization ability compared to other models. In addition, the influence of hyperparameters on the forecast accuracy of the new model has also been studied. These results play an important role in forecasting and preventing adverse vibrations such as stick slip, impact, reversal, and rebound of the drill bit.

Study on the Effects of Fe Doping on C‐ZFe Catalyst for Catalytic Removal of NO from the Low‐Temperature Flue Gas

AbstractThe denitrification efficiency of carbon‐based zero valent iron catalyst (C‐ZFe) for low‐temperature selective catalytic reduction (SCR) (<140°C) highly depends on the structural species of iron oxide (FexOy) and the physicochemical properties of the catalyst. In the study, we investigated the main factors affecting the low‐temperature denitrification efficiency of C‐ZFe such as temperature, iron content and O2. The results showed that the average NOX conversion was 72.6 % at 135°C when the space velocity was 459 h−1 and the mass ratio of carbon to iron was 15 % to 85 %. The surface morphology and structure of C‐ZFe were characterized by the surface area and pore size distribution measurements, X‐ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and X‐ray photoelectron spectroscopy (XPS). The results indicated that the iron on the catalyst surface was oxidized by O2 to Fe2O3, which could retain NO and then formed intermediate products. NO entered the mesoporous structure along C‐ZFe surface and proceeded a catalytic reduction reaction with the adjacent carbon.

A Study on Micro-Pit Texture Parameter Optimization and Its Tribological Properties

In this paper, the effect of micro-dimple textures (produced by a laser) on the tribological properties of bearings is investigated. This study offers guidelines to reduce the friction torque of the bearing pair and addresses the problem of difficult start-ups after shutdowns. Micro-pits with different texture diameters and depths were machined on the surface of journal bearings. Then, the impact of several different texture parameters on the tribological performance of the bearing pairs was studied using an orthogonal experimental design. Subsequently, the surface morphology of the bearings before and after the friction and wear test was observed using scanning electron microscopy (SEM) and energy-dispersive spectrometry (EDS). These observations were then used to determine the type/state of friction and wear, which also improves our understanding of how texture affects the service life of bearings. The results indicate that the bearings’ micro-pit surface hardness follows an approximate parabolic spatial distribution that decreases along the micro-pit wall. Furthermore, the laser processing of surface textures was found to cause hardening in certain areas, and the chemical composition of elemental carbon and oxygen at the inner surface of processed bearings increased by 31.1% and 7.9%, respectively. Moreover, abrasive wear was identified as the primary form of wear. The textured surface’s antifriction mechanism primarily functioned to trap particles, which acted as a secondary lubrication source and altered the lubrication states by serving as a medium for supplied lubricants. The results confirm that a suitable selection of texture parameters can not only effectively reduce the friction coefficient without shortening the service life of the bearing pair but also facilitate the smooth start-up of the rotor–bearing system.

Effect of Presodiation Additive on Structural and Interfacial Stability of Hard Carbon | P2‐Na0.66Mn0.75Ni0.2Mg0.05O2 Full Cell

The compatibility between a corncob‐derived hard carbon anode and a layered oxide cathode (Na0.66Mn0.75Ni0.2Mg0.05O2), as well as the effect of presodiation via cathode additive (Na2C4O4), are investigated in a sodium‐ion full cell. Extensive physicochemical and electrochemical characterizations are performed to deeply investigate the structural and interfacial evolution of the materials in the presodiated cell, either within the single cycle or upon long‐term cycling. The use of sacrificial cathode additives is generally regarded as a method to improve full cell performance, especially when using sodium‐deficient materials. However, undesired effects upon decomposition of the sacrificial salt may arise due to the complexity of the system. In this study, it is evidenced that the presodiation changes the properties of the electrodes causing a worsening of the electrochemical performance of the cell during long‐term cycling. The surface morphology of the cathode is negatively affected by the formation of holes/cracks, while redox processes associated with structural transformations are suppressed in the voltage window of interest, with partial structural deformations occurring during activation cycles. The SEI and CEI are also affected by the formation of insulating organic species, which lead to an increased thickness and interphase resistance hampering the charge transfer kinetics of the cell.

Duplex surface engineering of cold spray Ti coatings and physical vapor-deposited TiN and AlTiN thin films

The feasibility of a duplex coating based on cold spray technology and magnetron sputtering was evaluated for repair applications requiring a ‘thin-on-thick’ layered structure. Commercially pure angular-shaped Ti grade 4 particles are fed to a cold spray gun and accelerated toward a Ti alloy substrate to deposit thick coatings (∼4.5 mm). TiN and AlTiN thin films are deposited on polished cold spray coatings using a four-source closed-field unbalanced magnetron sputtering (CFUBMS) system. Microstructure was characterized using focused ion beam (FIB) lift-out, scanning electron microscopy (SEM), and electron channeling contrast imaging (ECCI). The nanoindentation technique was used to evaluate the mechanical properties of coatings. The H/E ratios and H3/E2 ratios for TiN films were found to be 0.098 and 0.26 GPa, respectively, while those for AlTiN films were measured at 0.066 and 0.052 GPa, respectively, suggesting higher capacity of TiN films to withstand both elastic and plastic deformation. Using scratch testing, the adhesion of TiN and AlTiN thin films to cold spray Ti was investigated, with TiN-Ti duplex coatings exhibiting better performance compared to AlTiN-Ti coatings. Tribological testing was performed on duplex coatings using a reciprocating tribometer equipped with an alumina ball counterface. The wear rate for AlTiN-Ti coatings after 2000 sliding cycles was found to be (1.0 × 10−3 ± 0.1 × 10−3 mm3/Nm), three orders of magnitudes higher than that for TiN-Ti (8 × 10−6 ± 2 × 10−6 mm3/Nm. SEM was used to reveal worn surface morphologies and cross-sectional analysis of the wear track. Subsurface microstructural changes due to wear were examined using focused ion beam cross-sectioning, revealing bending cracks and tribofilm formation.

Grape Seed Extract as an Environment-Friendly Green Inhibitor for Corrosion of Mild Steel in 1 M Sulfamic Acid

AbstractA corrosion inhibition study of mild steel in 1 M sulfamic acid was conducted using grape seed extract (GSE) as a possible green inhibitor. Electrochemical techniques were adopted to measure the corrosion rate in both the absence and presence of the GSE. Conditions were standardized to obtain optimum inhibition efficiency by varying the concentration of inhibitor and temperature. The kinetic parameters were calculated using the Arrhenius equation. Surface analysis was conducted by scanning electron microscope (SEM) and atomic force microscope (AFM) techniques. A suitable mechanism was proposed for the corrosion inhibition process. Grape seed extract showed a maximum efficiency of 65%, with a concentration of 0.24 g/L at 303 K from potentiodynamic polarization (PDP) studies. With the increase in temperature, the efficiency decreased, resulting in the GSE inhibitor’s physical adsorption. Surface morphology studies supported the adsorption of GSE on mild steel. GSE acted as an efficient green inhibitor with environmental benefits.

Improved rate capability and energy density of high-mass hybrid supercapacitor realized through long-term cycling stability testing and selective electrode design

To render supercapacitors (SCs) more practical, they must exhibit high cycling stability of at least ten thousand cycles with commercial-level mass loadings, which differentiates them from batteries. Metal-organic framework (MOF)-based electrode materials are promising for use in energy storage systems owing to their excellent electrochemical performance. In this study, we report the electroactivities of bimetallic MOFs (Co, Ni, and Co–Ni) using a single-step, facile, and cost-effective hydro/solvothermal method. To optimize their performances, we develop a general strategy for analyzing various binder-free MOFs. Additionally, the effects of the reaction time, reaction temperature, solvents, and elements (Ni, Co, and H2BDC) on the surface morphology and electrochemical performance are investigated. Based on an analysis of the electrochemical properties of all the synthesized electrode materials, the optimal electrode delivers an ultrahigh areal capacity of 2621 µAh cm−2 (297.1 mAh g−1) at 7 mA cm−2, with a high-rate capability of 82.5 % even at 40 mA cm−2. The optimized Co–Ni MOF electrode is employed as a positive electrode to fabricate an aqueous hybrid SC (HSC) with an activated carbon-coated nickel foam electrode as a negative electrode. The as-fabricated HSC exhibits excellent electrochemical properties with exceptional cycling stability (120k cycles) and improved rate capability (60 %). Additionally, we identify factors that contribute to improved redox reactions in the Co–Ni MOF-based HSC, such as the role of Co–Ni MOFs in the redox reaction and the influences of other structural parameters on charge storage and transfer processes. Our aim is to further understand the underlying mechanisms of the improved redox reactions and thus obtain new insights into the design and optimization of Co–Ni MOF-based HSCs. Finally, the energy storage properties of the HSC are validated by using it to power different electronic devices. The promising outcomes obtained in this work can serve as a basis for the future practical implementation of high-energy-density HSCs with high mass loadings and charging rates. SynopsisTo render the practicability of hybrid supercapacitor (HSC) with enhanced energy storage properties, we investigate the electroactivities of bimetallic metal-organic frameworks (MOFs) (Co, Ni, and Co–Ni) using a single-step, facile, and cost-effective hydro/solvothermal method. To optimize their performances, a general strategy is developed for analyzing various binder-free MOFs. Additionally, the effects of the reaction time, reaction temperature, solvents, and elements (Ni, Co, and H2BDC) on the surface morphology and electrochemical performance are studied. In addition, we validate the energy storage properties of the HSC by using it to power different electronic devices. The promising outcomes obtained in this study can serve as a basis for the future practical implementation of high-energy-density HSCs with high mass loadings and charging rates.

Preparation and characterization of physical properties of molded pulp from empty fruit bunches of oil palm

This research aims to determine the impact of pretreatment on empty fruit bunches (EFB) of palm oil fibers before the pulping process on the quality of the molded pulp produced. The study includes EFB fiber pretreatment processes, pulp production, pulp molding, physical characteristic analysis, and molded pulp performance evaluation. The pulp production process involves acid-base hydrolysis reactions. The produced molded pulp is done manually. Characterization of the molded pulp includes measurements of paper grammage, thickness, density, and moisture content. The characteristics of pulp produced from pretreated EFB fibers are as follows: an average grammage value of 415.48 g/m², paper thickness of 1.53 mm, water absorption capacity of 13.33-33.33%, density of paper of 0,026 x 106 - 0,027 x 106 g/m3, and a smooth surface morphology. Meanwhile, the characteristics of pulp produced from without pretreatment EFB fibers include an average grammage value of 372.18 g/m², paper thickness of 0.77 mm, water absorption capacity of 20.34-43.21%, density of paper of 0,004 x 106 - 0,008 x 106 g/m3, and a rough surface morphology due to pores on the fiber surface.

Novel ionic polymers encompassing di-cationic pyridinium hydrazones and aromatic ester as potent antimicrobial agents against resistant bacteria

In this work, readily achievable synthetic pathways including quaternization, metathesis and copolymerization reactions were utilized for the construction of a new di-pyridinium monomers and their respected ionic polymers scaffold with ester fragments. All synthesized material were well characterized by spectroscopic experiments. The surface morphology and thermal study of the produced polyesters were carried out using SEM, PXRD, and TGA analysis. The impact of the counter anions on the crystallinity and thermal analysis of the polymer network was confirmed by thermal analysis and surface investigation. The related polyesters' crystallinity was decreased, and their thermal stability was increased by the TFSI anion. Various significant consequences regarding the development of innovative antibacterial agents along with specific therapies. Subsequently, we evaluated the antimicrobial, antibiotic resistant strains, and anti-prophage properties of these novel class of ionic and poly-ionic materials. Throughout antibacterial studies, the M-Br monomer excelled all synthesized materials, although PPy-TFSI and its monomer outperformed antibiotic-resistant organisms. Both M-PF6 and PPy-PF6 decreased S. aureus bacteriophage proliferation. Understanding the bacterial species or strains that are vulnerable to polyesters encourages subsequent studies in this field to focus on creating targeted therapies for illnesses caused by these pathogens.

Strong Magnetic p-n Heterojunction Fe3O4-FeWO4 for Photo-Fenton Degradation of Tetracycline Hydrochloride

With the abuse of antibiotics, its pollution poses an increasing threat to the environment and human health. Effective degradation of organic pollutants in water bodies is urgent. Compared to traditional treatment methods, advanced oxidation processes that have developed rapidly in recent years are more environmentally friendly, efficient and applicable to a wider range of organic compounds. FeWO4 was used in this study as the iron-based semiconductor material to modify and optimize the material design. Fe3O4/FeWO4 composites were prepared by a two-step hydrothermal method. The crystal structure, surface morphology, electrochemical properties and separability of the composite semiconductor were analyzed by XRD, XPS, UV-vis, SEM, EDS and Mott-Schottky. The results showed that, when the initial contaminant concentration was 30 mg/L, the initial solution pH was 4, the dosage of the catalyst was 25 mg and the dosage of hydrogen peroxide was 30 μL, the degradation efficiency of tetracycline hydrochloride (TCH) could reach 91% within 60 min, which was significantly improved compared to the performance of the single semiconductors Fe3O4 and FeWO4. In addition, the catalyst prepared in this experiment can be easily recovered by magnetic separation technology in practical application, which will not affect the turbidity of water while reducing the cost of catalyst separation and recovery.

Pb(II) solid-phase extraction in wastewater samples prior to flame atomic absorption spectrometry analysis using chitosan and alginate modified carbon

ABSTRACT The sustainability concept was kept in view by designing and synthesising a novel adsorbent for Pb(II) ion, using natural and metal-free precursors which are renewable and biodegradable, i.e. alginate, chitosan, and carbon. The study was aimed to introduce the synthesis of Carbon/Alginate/Chitosan composite (CAC) as a beneficial adsorbent tailored for the solid-phase extraction (SPE) of Pb(II) prior to its analysis via flame atomic absorption spectrometry (FAAS). The successful preparation of the CAC material is elucidated, characterised through FTIR for functional group analysis, and evaluated for surface morphology and elemental composition via SEM-EDX. Optimisation of SPE parameters was carefully conducted to enhance adsorption-desorption efficiency across diverse conditions. These optimised factors were a pH level of 6, initial Pb(II) concentration of 20 mg/L, sample flow rate 5 mL/min, elution utilising Na2EDTA at a rate of 5 mL/min, sample volume of 20 mL, Na2EDTA eluent volume of 10 mL, and Na eluent concentration of 0.5 M. Application of CAC-based SPE for Pb(II) analysis in wastewater samples under these optimised conditions yielded exceptional recovery rates of 93–96%, with a limit of detection (LoD) value of 71.4 µg/L. Moreover, a notable preconcentration factor of 4–8 times is achieved for Pb(II) in wastewater samples, facilitating the detection of Pb(II) concentrations as low as 30 µg/L.

Microwave assisted synthesis of NiMn<sub>2</sub>O<sub>4</sub> as electrode material for supercapacitor applications

In this work, spinel NiMn2O4 was successfully synthesized through microwave assisted co-precipitation method and followed by calcination at 500°C. The crystal structure and the presence of functional groups in NiMn2O4 were characterized through X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The surface morphology was examined by field emission scanning electron microscopy (FE SEM). From the BET analysis surface area and average pore diameter of the mesoporous NMO nanoparticles are calculated to be 10.513 m2g-1and 8.55nm. The electrochemical performance of material as electrode material for supercapacitor applications was analysed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific capacitance of the NMO electrode increased from 290.56 F/g to 751.57F/g with increase concentration from IM KOH to 6M KOH at scan rate of 5mV/s. These results indicate spinel NiMn2O4 as a promising candidate for high performance energy storage applications.