FESEM Analysis Research Articles

Synthesis, characterization, and catalytic performance of Ni supported on sustainable POFA-derived SBA-15 for hydrogen-rich syngas from CO2 reforming of methane

Palm Oil Fuel Ash (POFA) is massively produced by numerous palm oil mills worldwide, creating an environmental waste disposal problem. Notably, POFA serves as a cost-effective alternative silica source instead of the expensive tetraethyl orthosilicate (TEOS). This research focused on synthesizing SBA-15 from POFA waste and examining the effect of promoters on POFA-derived SBA-15-supported Ni-based catalysts. The 10 wt% Ni/SBA-15-POFA catalyst was sequentially impregnated with promoters having 1 wt% loading of Zr, Ce, La, and Cr. The catalysts were tested for CO2 methane reforming (CMR) at 800 °C for 8 hours while maintaining a stoichiometric feed ratio. Various characterization techniques, including XRD, FESEM, XPS, H2-TPR, CO2-TPD, and BET analysis were employed to assess the catalyst physicochemical properties. The addition of promoter changed the properties of catalyst. Except for Cr-promoted catalyst, the addition of promoters positively impacted catalytic performance, activity, and stability. XRD analysis showed that Cr addition had detrimental effects on the crystallite structure of the Ni/SBA-15-POFA catalyst. In contrast, Zr, Ce, and La additions significantly reduced the crystallite size and improved active metal dispersion. Overall, the Zr-promoted catalyst exhibited the best performance in terms of activity and stability, with a CH4 conversion of 90 % and CO2 conversion of 94.4 %. The spent catalyst characterization, including XRD, FESEM, O2-TPO, and RAMAN, showed that promoter addition significantly reduced carbon deposition. The stable and superior perfromance of Zr-promoted catalyst was attributed to the production of MWCNTs. Conversely, the rapid deactivation of the unpromoted catalyst may be due to the formation of amorphous carbon, which tends to quickly block active sites and reduce the catalytic activity.

Experimental investigation in enhancing the mechanical, wear and corrosion resistance properties of Al6061-SiC-NSA composites fabricated using stir casting process

The study investigates the mechanical, and tribological properties of Al6061-SiC-NSA hybrid composites. The characterization via FE-SEM reveals NSA particle’s crystal structure and agglomeration, with an average particle size of approximately 400 nm. The EDS analysis confirms the presence of oxides (TiO2, SiO2, Fe2O3, Al2O3) along with calcium and potassium. The XRD spectra corroborate these findings, additionally identifying Calcite and intermetallic compounds. The Al6061–5SiC-10NSA composites has improved compressive strength of 254 MPa compared to 220 MPa for base Al6061 alloy. The tensile strength of base Al6061 (100 MPa) decreased to 70 MPa for Al6061–5SiC-20NSA composites. The tensile strength decreases with increasing NSA content. Fracture analysis indicates ductile fracture mechanisms, supported by FE-SEM images displaying honeycomb-like structures and dimples. Impact testing reveals reduced impact strength in composites compared to Al6061 (26J3), with Al6061–10SiC-5NSA exhibiting the best toughness of 22.5 J3. Density decreases in composites, with density of Al6061–5SiC-20NSA composites has reduced to 2.40 g cm−3. The microhardness of Al6061–10SiC-5NSA has better value of 109 HV, whereas further addition of NSA has resulted in decrease in microhardness of composites. Pin-on-disc wear tests demonstrate improved wear resistance with increased NSA content, with Al6061–5SiC-20NSA outperforming other compositions. COF decreases with increased NSA content and sliding speed. FE-SEM analysis of worn surfaces reveals that the major wear mechanism is adhesive wear followed by delamination, further the oxide formation along the surface aiding wear resistance of the composites. Tafel testing indicates decreased corrosion potential with increased NSA content, with Al6061–5SiC-20NSA exhibiting improved corrosion resistance.

Influence of surface finishing on the outcome of a 3-point bending test in polymer-based dental composits assessed by qualitative and quantitative fractography

ObjectivesThe aim of the study was to evaluate the influence of surface finishing in three polymer-based composits (composits) on the result of a 3-point bending test using quantitative and qualitative fractography as well as microstructural characteristics. Materials and methods270 rectangular specimens (n = 30) of three composits were prepared, stored and tested according to NIST No. 4877. Prior testing, the samples were subjected to three surface treatments: 1) no treatment, to preserve the oxygen inhibition layer, 2) with FEPA P1200 (ANSI equivalent grit 600) SiC paper abraded surface, and 3) polished surface. A three-point bending testing was employed, followed by quantitative (assessment of reason for failure and fracture pattern) and qualitative (fracture mirror measurements) fractography, 3D and 2D surface imaging, surface roughness, reliability and Fe-SEM analysis. The mirror radius that runs in the direction of constant stress was used to calculate the mirror constant (A) using Orr's equation. Uni- and multifactorial ANOVA, Tukey's post hoc test, and Weibull analysis was performed for statistical analysis. ResultsSurface finishing has less influence on the fracture pattern, reliability and mechanical parameters and has no influence on the mirror constant. The amount of inorganic filler has a direct impact on flexural strength and modulus, while the ranking of materials was independent of surface treatment. Failures initiated by volume defects were the most common failure mode (77.0%) with surface defects accounting for 14.9% (edge) and 7.7% (corner). Polishing resulted in lower peak-to valley height compared to no treatment, both 3–4 times lower compared to the 600 grit treatment. The increase in roughness within the analyzed range did not lead to an increase in surface-related failures. ConclusionsThe clear dominance of volume defects in all examined materials as a cause of material fracture reduces the impact of roughness on the measured properties. This insight was only possible using qualitative and quantitative research fractography.

Synthesis of ultrastable silver catalyst supported on alumina nanofibers for carbon monoxide combustion

A catalyst consists of fine aggregates nanoflowers of alumina as support and uniform coating of silver as active component was fabricated to oxidize carbon monoxide. The alumina nanofibers synthesized via a simple electrochemical method. XRD and FE-SEM analysis showed that the thickness of silver deposit was in the range of subnanometer. Elemental mapping also showed a uniform distribution of silver. Also, BET and EDX tests were performed to measure the specific surface area and elemental composition of the catalyst, respectively. Its catalytic activity was measured, and at GHSV equal to 60000 ml/h.g, the end temperature of the oxidizing reaction was 175°C. By increasing the GHSV to 120,000 ml/h.g, the end temperature of the reaction reached 190°C. The thermal stability of the catalyst was also high, as the specific surface area of the catalyst changed from 87m2/g to 51m2/g by increasing the temperature from ambient temperature to 900°C. Due to the high stability of alumina, the structure of the catalyst is always stable. On the other hand, feasibility studies have been given special attention to the advancement of the project. Therefore, for the synthesis of nanocatalyst, available precursors and a simple method have been used, so there will be no problem in the mass production of the catalyst. It is hoped to be able to synthesize nanocatalysts with similar structure and mass production capability for other chemical reactions with this method.

Controlled reaction dynamics of cellulose: Revealing the dual morphology nanocrystals

Cellulose nanocrystals exhibit diverse morphology with embedded crystallinity derived from the ordered crystalline regimes of cellulose fibers. Acid hydrolysis parameters controls the morphology of nanocrystals and is the primary efficient route for the synthesis of cellulose nanocrystals. In this study, we explored the impact of temperature on the morphology engineering of cellulose nanocrystals derived from banana pseudostem by oxalic acid hydrolysis, an underexplored method. Confirmation of successful cellulose extraction was achieved through fibrous morphology observed in FESEM and TEM analyses. X-ray diffraction and Raman spectroscopy affirmed the presence of type II cellulose. Notably, for the first time, we report the derivation of toroidal and spherulitic sheet-like morphologies in cellulose nanocrystals synthesized by hydrothermal method from banana psuedostem. Our investigation revealed that cellulose hydrolysis at 120 °C yields nanocrystals characterized by toroidal and spherulitic sheet-like morphologies with excellent crystallinity, as confirmed by FESEM and TEM analyses, with average thicknesses of 13.70 nm and 18.05 nm, respectively. Interestingly, elevating the hydrolysis temperature to 180 °C led to the collapse of these structures into carbon dots, exhibiting notable cyan emission.

Anticancer potential of silver nanoparticles biosynthesized using Catharanthus roseus leaves extract on cervical (HeLa229) cancer cell line

Cervical cancer is a significant global health issue among women due to its prevalence and impact on morbidity and mortality, especially in low- and middle-income countries. This underscores the critical necessity for the development of anticancer treatments that are not only more efficient but also safer. This study introduces a novel approach to combating cervical cancer by synthesizing silver nanoparticles (AgNPs) using aqueous Catharanthus roseus leaves extract and evaluating their anticancer activity. The aqueous extract of C. roseus showed remarkable potential to reduce silver ions rapidly. UV–Vis spectroscopy confirmed the formation of AgNPs, with a characteristic surface plasmon resonance (SPR) band observed at 429 nm. TEM/EDX and FE-SEM analysis confirmed the presence of spherical AgNPs with uniform size distribution. XRD analysis confirmed the face-centered cubic (FCC) structure of metallic silver in AgNPs. Moreover, AgNPs exhibited significant antiproliferative and cytotoxic effects on HeLa229 cells, with higher selectivity towards cancer cells compared to normal cells. Moreover, wound healing assays showed the robust antimetastatic potential of AgNPs by inhibiting cancer cell migration. The real-time reverse transcription polymerase chain reaction analysis demonstrated the impact of AgNPs on inducing apoptosis and cell cycle arrest. Overall, these findings highlight the promising role of Ag-NPs synthesized from C. roseus extract as effective anticancer agents,offering a promising alternative to conventional chemotherapy with potentially reduced side effects and increased efficacy.

Granulated graphene oxide-activated carbon for adsorptive removal of diclofenac sodium and ibuprofen in a continuous fixed-bed column

The granular graphene oxide-activated carbon (GGA) composite was synthesized with polyvinyl alcohol (PVA) and malonic acid (MA) as chemical crosslinker at different conditions. GGA synthesis was performed at different parameters including binder-to-powder ratio in the range of 0.5–1.2, synthesis time in the range of 2–24 h, and drying temperature in the range of 60–110 °C. Response surface methodology (RSM) was used to optimize the synthesis parameters of the adsorbent synthesis. The optimum parameters for synthesis were achieved at a binder-to-powder ratio of 0.875, a synthesis time of 23.992 h, and a drying temperature of 60.071 °C. XRD, FTIR, FE-SEM, BET and TGA analyses were used to discuss the characteristics of the adsorbent structures. The surface area and mechanical stability were found to be 156.59 m2/g and 95.417 %, respectively. The adsorption behavior of mono-components (diclofenac sodium (DCF)/ibuprofen (IBP)) and bi-components (DCF + IBP) on the GGA was evaluated in a fixed-bed column. The effects of column operating parameters, including bed mass (m: 0.25–0.75 g), flow rate (Q: 5–9 mL/min), and adsorbate concentration for DCF (C: 20–100 mg/L) and IBP (C: 5–15 mg/L) on the breakthrough curves were investigated. The experimental data of fixed-bed column were correlated with breakthrough models such as Thomas, Bohart-Adams, Yoon-Nelson, Yan, Gompertz, and Log-Gompertz via both linear (under different column operating conditions) and nonlinear (for DCF (Co of 60 mg/L; m of 0.5 g and Q of 7 mL/min) and IBP (Co of 10 mg/L; m of 0.5 g and Q of 7 mL/min)) regression analysis. The maximum adsorption capacities calculated by the Thomas model were 110.068 and 34.912 mg/g for DCF and IBP, respectively. In bi-component systems, antagonistic behavior was observed in the adsorption of DCF and IBP. The results showed that the GGA can successfully remove DCF and IBP through a fixed-bed adsorption column.

Production of Agarose-Hydroxyapatite Composites via Supercritical Gel Drying, for Bone Tissue Engineering.

Bone tissue engineering (BTE) is the most promising strategy to repair bones injuries and defects. It relies on the utilization of a temporary support to host the cells and promote nutrient exchange (i.e., the scaffold). Supercritical CO2 assisted drying can preserve scaffold nanostructure, crucial for cell attachment and proliferation. In this work, agarose aerogels, loaded with hydroxyapatite were produced in view of BTE applications. Different combinations of agarose concentration and hydroxyapatite loadings were tested. FESEM and EDX analyses showed that scaffold structure suffered from partial closure when increasing filler concentration; hydroxyapatite distribution was homogenous, and Young's modulus improved. Looking at BTE applications, the optimal combination of agarose and hydroxyapatite resulted to be 1% w/w and 10% w/v, respectively. Mechanical properties showed that the produced composites could be eligible as starting scaffold for BTE, with a Young's Modulus larger than 100 kPa for every blend.

Adsorption of arsenic and fluoride: Modeling of single and competitive adsorption systems

The elevated co-occurrence of arsenic and fluoride in surface and groundwater poses risks to human health in many parts of the world. Using single and competitive batch equilibrium adsorption studies, this research focuses on As(V) and F adsorption by activated carbon and its modeling. BET, XRD, FESEM, EDS, and FTIR analysis were used to discern the structural characteristics of activated carbon. The influence of dosage, pH, and contact time were also investigated in single and simultaneous adsorption systems. The maximum adsorption capacity of activated carbon for arsenic and fluoride were found to be 3.58 mg/g and 2.32 mg/g, respectively. Kinetics studies indicated that pseudo-second-order kinetic model fit better than pseudo-first-order, Elovich, and intraparticle diffusion kinetic models. The non-linear regression analysis of Langmuir, Freundlich, Toth, Redlich Petersons, and Modified Langmuir Freundlich models was used to determine single-component asorption model parameters. Additionally, the simultaneous adsorption was rigorously modeled and compared using the Extended Langmuir (EL), Extended Langmuir Freundlich (ELF), Modified Competitive Langmuir (MCL), and Jeppu Amrutha Manipal Multicomponent (JAMM) isotherm models, and competitive mechanisms were interpreted for the simultaneous adsorption system. Further, the model performances were evaluated by statistical error analysis using the normalized average percentage error (NAPE), root mean square errors (RMSE), and the correlation coefficient (R2). According to the modeling results, single equilibrium data fitted better with the Modified Langmuir Freundlich isotherm model, with a higher R2 of 0.99 and lower NAPE values of 3.8 % and 1.28 % for As(V) and F, than other models. For the binary adsorption, the Extended Langmuir Freundlich isotherm model demonstrated excellent fit with lowest errors. All the competitive isotherm models fit the As(V) and F simultaneous sorption systems reasonably well. Furthermore, the research unveiled a nuanced hierarchy of isotherm fitting, with ELF > EL > MCL > JAMM in varying arsenic at a constant fluoride concentration, and ELF > JAMM > EL > MCL in varying fluoride at a constant arsenic concentrations. In addition, competitive studies divulged crucial insights into selective adsorption, as As(V) exhibits a pronounced adsorption selectivity over F on activated carbon. In essence, As(V) showed a more pronounced antagonistic behavior over F, whereas F exhibited a much lesser competitive behavior in the adsorption of arsenic.

Temperature-Induced Conversion of 2D Vanadium-Doped MoSe2 Nanosheets to 1D V2MoO8 Rods: Enhanced Performance in Electrochemical Antibiotic Detection in Biological and Environmental Samples.

In this work, new strategies were developed to prepare 1D-V2MoO8 (VMO) rods from 2D V-doped MoSe2 nanosheets (VMoSe2) with good control over morphology and crystallinity by a facile hydrothermal and calcination process. The morphological changes from 2D to 1D rods were controlled by changing the calcination temperature from 300 to 600 °C. The elimination of Se and the incorporation of O into the V-Mo structure were evaluated by TGA, p-XRD, Raman, FE-SEM, EDAX, FE-TEM, and XPS analyses. These results prove that the optimization of the physical parameters leads to changes in the crystal phase and textural properties of the prepared material. The VMoSe2 and its calcined products were investigated as electrochemical sensors for the detection of the antibacterial drug nitrofurantoin (NFT). At a calcination temperature of 500 °C, the modified screen-printed carbon electrodes (SPCE) proved to be an excellent electrochemical sensor for the detection of NFT in neutral media. Under the optimized conditions, VMO-500 °C/SPCE exhibits low detection limit (LOD) (0.015 μM), wide linear ranges (0.1-31, 47-1802 μM), good sensitivity, and selectivity. The proposed sensor was successfully used for the analysis of NFT in real samples with good recovery results. Moreover, the reduction potential of NFT agreed well with the theoretical analysis using quantum chemical calculations, with the B3LYP with 6-31G(d,p) basis set predicting an E0 value of -0.45 V. The interaction between the electrode surface and NFT via the LUMO diagram and the electrostatic potential surface is also discussed.

Synthesis of WL.nZVI/ GAC adsorbent green for chromium removal from aqueous solutions (Characterization, kinetics, isotherms, and thermodynamics)

This paper aims to synthesize zero-valent iron green nanoparticles to remove chromium from aqueous solutions. A granular activated carbon base was used to solve the problem of nanoparticle agglomeration. This study produced zero-valent iron nanoparticles using walnut leaf extract and immobilization on granular activated carbon (WL.nZVI/ GAC). Then, the specifications of the nanocomposite were studied using FE-SEM, EDX, BET, FTIR, and XRD analysis. This study investigated the parameters affecting adsorption, such as pH, adsorbent dose, contact time, pollutant concentration, and temperature. The WL.nZVI/ GAC nanocomposite specifications showed that the nanoparticles are spherical, and the diameter of the iron nanoparticles immobilized on activated carbon was determined in the range of 16.77 to 27.72 nm. XRD results also indicated that the Wl.nZVI/ GAC adsorbent was amorphous. According to EDX analysis, the loaded iron content in WL.nZVI/ GAC was about 1.86 %. pHPZC for WL.nZVI/ GAC nanocomposites was determined in the range of 6.1; In other words, at pH less than 6.1, the adsorbent’s surface charge is positive and can absorb the chromium existing in solution, which is in the form of chromate, well. The results of adsorption process optimization showed that the adsorption of Cr(VI) is optimal at pH = 4, contact time of 780 min, concentration of 80 ppm, and temperature of 298 K. Experimental studies showed that the chromium removal by adsorbent is strongly dependent on pH. The adsorption kinetics of chromium by WL.nZVI/ GAC adsorbent follow the Pseudo-second-order, and the adsorption isotherm follows the Langmuir model. The adsorption of Cr(VI) ions on the Wl.nZVI/ GAC adsorbent is a spontaneous and exothermic process.

Unlocking the therapeutic potential: Green synthesized zinc oxide/silver nanoparticles from Sophora pachycarpa for anticancer activity, gene expression analysis, and antibacterial applications

Hematologic malignancies and bloodstream infections rank among the most lethal medical conditions. Research on new treatments for these diseases is crucial. In this study, we investigated the anticancer properties and molecular mechanisms of zinc oxide nanoparticles doped with silver synthesized using a green approach involving Sophora pachycarpa (S. pachycarpa) plant seed extract (SPS@ZnO/Ag NPs). Additionally, we explored the antibacterial effects of these nanoparticles and S. pachycarpa extract. The SPS@ZnO/Ag NPs were characterized using XRD, FTIR, zeta potential, EDS, FESEM, and TEM analyses. Subsequently, we assessed the viability of K562 cells in the presence of different nanoparticles and extract. Molecular mechanisms underlying cell death were examined through flow cytometry analysis, Hoechst staining, and relative expression of pro-apoptotic genes (Apaf-1, Cytochrome c, Caspases 3, 6, 9) relative to the gene B-actin. Also, BAX/BCL2 ratio was determined. Antibacterial effects were evaluated against Gram-negative and Gram-positive bacteria. The results confirmed successful synthesis of spherical SPS@ZnO/Ag NPs with positive surface charge, purity, and size ranging from 50 to 65 nm. SPS@ZnO/Ag NPs significantly reduced K562 cell viability compared to S. pachycarpa extract and chemical nanoparticles, with the 1:1 ratio of zinc oxide and silver nitrate exhibiting the highest cell death. The findings from flow cytometry analysis, Hoechst staining, and molecular pathway analysis indicate that SPS@ZnO/Ag NPs induce cancer cell death through apoptosis. Evaluation of antibacterial properties demonstrated the destruction of all studied strains by SPS@ZnO/Ag NPs. Overall, our study demonstrates that green synthesis, in comparison to chemical synthesis, exerts a notable impact on the anticancer properties of zinc oxide nanoparticles doped with silver. Moreover, SPS@ZnO/Ag NPs exhibit targeted induction of cancer cell apoptosis, showcasing their potential application in biomedical fields.

Optimization and modeling of solar photocatalytic degradation of raw textile wastewater dyes using green ZnO-ED NPs by RSM

ABSTRACT This study aims to use green ZnO-ED NPs produced from Eleocharis dulcis (E. dulcis) extract to maximize solar photocatalytic degradation of raw textile wastewater. The optimization of photocatalysis was decided using the response surface methodology (RSM) as a function of ZnO-ED NPs mass load (0.1–2 g), initial concentration (10–100%), pH (4–9), and contact time (60–200 min). The maximum decolorization (87.34%) and COD removal (100%) were recorded at pH 7, time (60 min), ZnO-ED NPs dosage (2 g/L), and 10% of color concentrations with R2 coefficient of 0.78 at p < 0.05. FESEM analysis showed the presence of granules with smaller diameters than the diameter of the ZnO-ED NPs granules before SPD. EDX analysis revealed the presence of impurities like copper (Cu). XRD analysis indicated the purity of ZnO-ED NPs after SPD, as the values were all quite similar to the XRD values before SPD. The results of an AFM analysis presented that agglomerations of ZnO-ED NPs, in contrast, were somewhat homogeneous in size, nature, and dispersion before SPD.

The anticancer impact of folate-linked ZnO-decorated bovine serum albumin/silibinin nanoparticles on human pancreatic, breast, lung, and colon cancers

In the current study, we aimed to design an individual hybrid silibinin nano-delivery system consisting of ZnO and BSA components to study its antioxidant activity and apoptotic potential on human pancreatic, breast, lung, and colon cancer cell lines. The folate-linked ZnO-decorated bovine serum albumin/silibinin nanoparticles (FZBS-NP) were synthesized and characterized by FTIR, FESEM, DLS, and zeta potential analysis. The FZBS-NP’s cytotoxicity was evaluated by measuring the cancer cells’ (MCF-7, A549, HT-29, and Panc) viability. Moreover, the apoptotic potential of the nanoparticles was studied by conducting several analyses including AO/PI and DAPI cell staining analysis, apoptotic gene expression profile (BAX, BCL2, and Caspase-8) preparation, and FITC Annexin V/PI flow cytometry. Finally, both antioxidant assays (ABTS and DPPH) were utilized to analyze the FZBS-NPs’ antioxidant activities. The 152-nm FZBS-NP significantly induced the selective apoptotic death on the MCF-7, A549, HT-29, Panc, and Huvec cancer cells by increasing the SubG1 cell population following the increased treatment concentrations of FZBS-NP. Moreover, the FZBS-NPs exhibited powerful antioxidant activity. The BSA component of the FZBS-NPs delivery system improves the ability of the nanoparticles to gradually release silibinin and ZnO near the cancer cells. On the other hand, considering the powerful antioxidant activity of FZBS-NP, they have the potential to selectively induce apoptosis in human colon and breast cancer cells and protect normal types, which makes it an efficient safe anticancer compound. However, to verify the FZBS-NP anti-cancer efficiency further cancer and normal cell lines are required to measure several types of apoptotic gene expression.

Bandgap engineering of novel Cu-vanadate/g-C3N4 hierarchical nanoflowers for enhanced photodegradation and excellent biosensing capability

Copper vanadate and graphitic carbon nitride (g-C3N4) are pivotal materials in the realm of advanced materials science, owing to their distinctive optical and electronic conductive properties. In the context of environmental photocatalysis and biosensing applications, their synergistic combination holds significant promise. Copper vanadate, renowned for its optical and electronic properties, complements the unique architecture and optical conduction characteristics of g-C3N4. Together, these materials exhibit immense potential for driving advancements in environmental sustainability and diagnostic techniques. In this study, we report the synthesis of copper vanadate (Cu0.261V2O5) and its composite with graphitic carbon nitride. XRD confirms the synthesis of the novel phase, FESEM and TEM analysis reveals hierarchical nanoflowers and UV-Visible spectroscopy divulges the visible light activation of the synthesized material and aids in the calculation of the optical bandgap. Interfacial charge transfer was studied with the help of EIS and Mott-Schottky analysis was employed to reveal the semiconductor type (n or p type) and determine the band edges. The as-prepared material was tested for the photocatalytic removal of methylene blue (MB), followed by the study of reaction kinetics, cyclic stability and active radicals participating in the photocatalysis process. The synthesized heterojunction showed 100 % removal of MB within a tenure of 90 minutes. The results of the experiment revealed that Cu0.261V2O5 decorated with g-C3N4 displays 1.5 and 1.4 times better photocatalytic degradation capability than pure Cu0.261V2O5 and g-C3N4, respectively. Furthermore, the synthesized material was evaluated for electrochemical biosensing of ascorbic acid in PBS (pH 7) analyte using a 3-electrode system. Compared to the pure material, the heterojunctions drew 1.9 times more current and provided near unity correlation (R2). It is evident that Cu0.261V2O5 decorated with g-C3N4 can be implemented for commercial eco-remediation and electrochemical ascorbic acid sensing.

Revolutionising pesticide detection: a high-sensitivity electrochemical sensor with CdS/g-C3N4/MWCNTs for paraquat monitoring

ABSTRACT Over a decade, the Malaysia National Poison Centre found that 40% of pesticide poisoning cases may be linked to excessive paraquat (PQ) in water, soil, or food, underscoring the widespread impact on public health and emphasising the importance of detecting even trace amounts of PQ residues in the environment. Thus, this study presents a novel electrochemical sensor based on multiwalled carbon nanotubes (MWCNTs) reinforced cadmium sulphide co-anchoring on graphitic carbon nitride (CdS/g-C3N4) nanocomposites for PQ detection. The CdS/g-C3N4 nanocomposite was successfully synthesised and characterised through FTIR, XRD, EDX, FESEM and TEM analysis. The modified electrode (CdS/g-C3N4/MWCNTs PE) exhibited improved electrocatalytic activity, as demonstrated by cyclic voltammetry (CV) and impedance spectroscopy. The CdS/g-C3N4/MWCNTs PE displayed a high CV peak and low Rct value which corresponded to a higher electron transfer rate, reduced charge transfer resistance and enhanced mass transport properties. The electrochemical sensor’s performance was evaluated for the detection of PQ, and it demonstrated a linear response in a range of 1.0 µM to 0.1 mM with a limit of detection of 0.14 μM. Furthermore, the sensor exhibited selectivity with a less than 16% potential interference from various organic chemicals and inorganic ions. The sensor’s applicability was tested by quantifying PQ in real water samples, showing excellent recovery percentages ranging from 98.9% to 102.0%. The developed electrochemical sensor provides a practical solution for the rapid and accurate monitoring of PQ levels in the environment. This work establishes the foundation for the development of a selective electrochemical sensor for pesticide analysis, addressing both public health and environmental concerns.

Study of graphene incorporation into ZnO-PVA nanocomposites modified electrode for sensitive detection of cadmium

The presence of heavy metals often causes significant health risks, particularly cadmium, which is known for its high toxicity. In this study, a glassy carbon electrode was successfully modified by incorporating ZnO-PVA-Graphene nanocomposite, leveraging the excellent electrical properties and electron mobility of the material. Comprehensive material analysis, including XRD, confirmed that ZnO maintained its hexagonal wurtzite crystal structure despite the addition of graphene. Moreover, FESEM analysis showed that increasing graphene concentration led to a reduction in ZnO particle size by 85, 68, and 52 nm, respectively, accompanied by a decrease in band gap energy, as verified by UV–Vis measurements. Photoluminescence tests were also conducted and the result showed a noticeable blue shift in ZnO-PVA-Graphene nanocomposites compared to ZnO-PVA, specifically in the near band-edge (NBE) UV emission within the 374–379 nm wavelength range. Through I–V characterization, the optimal graphene concentration for cadmium detection was identified as 1.5 wt% in ZnO-PVA-Graphene nanocomposites, showing an approximate ohmic response. Meanwhile, square-wave voltammetry analysis of cadmium concentrations ranging from 0 to 80 ppm produced a coefficient of determination of 0.98926 and a Limit of Detection (LOD) of 9.88 ppm. These results showed the significant potential of ZnO-PVA-Graphene nanocomposites as a promising material for further development as an effective electrode modifier, enhancing the sensitivity of detection systems.

Investigation of antimicrobial potential of nanocomposites based on functionalization of graphene oxide with zinc porphyrin complexes

Herein, zinc porphyrin complexes were synthesised by passing through the formation of free base porphyrin ligands and metalation of free base porphyrins with zinc metal ions. The synthesised zinc porphyrin complexes were functionalised with graphene oxide leading to the formation of zinc porphyrin anchored graphene oxide hybrid nanocomposites. The zinc porphyrins complexes were anchored with graphene oxide through the particular functional group present at the periphery of zinc porphyrins (hydroxyl and carboxyl functional groups in Pr1 and Pr2 respectively). 1H NMR and UV–visible spectroscopic techniques have monitored the successful formation of free base porphyrins and their matching zinc-integrated metalloporphyrin complexes. Various spectroscopic techniques like, photophysical properties (UV–Visible spectroscopy and Fluorescence spectroscopy), Fourier transform infrared (FT-IR), powdered X-ray diffraction (P-XRD) patterns, FE-SEM and EDAX analysis were used to examine the intrinsic characteristics of the prepared nanocomposites. The in-vitro antimicrobial activity of the synthesized complexes and nanocomposites was tested against Staphylococcus aureus gram-positive strain, Klebsiella pneumonia, and Escherichia coli. By working on the antimicrobial behaviour, it has been observed that the compound containing –COOH substitute has shown enhanced antimicrobial activity. The in silico molecular docking studies of the synthesized compounds with the S. aureus nucleoside diphosphate kinase receptor showed strong interactions via hydrogen bonding, π − π interactions and hydrophobic interactions. Molecular dynamics (MDs) simulations were used to study the dynamic behaviour of the complexes as well as nanocomposites which revealed the stability of docked structures with S. aureus nucleoside diphosphate kinase receptor. The in-silico pharmacokinetics studies showed the drug-likeness, non-toxic nature and safe oral administration of the synthesized compounds.

Unraveling the morphology-structure-property relationship of silver orthovanadate p-semiconductor: Experimental and theoretical investigation

Silver vanadate (Ag3VO4) is considered one of the most important semiconductors. It finds practical applications in electrochemical cells, as bactericidal and virucidal agents, in photocatalysis, and environmental remediation. Despite the impressive experimental progress, the dependence of the properties of a material is strongly linked to its chemical composition and structure. In this sense, the peculiar physical-chemical properties of the vanadate's class have become important. However, the fundamentals of structure in this material remain poorly understood, and the theoretical insight into the morphology linked to its properties is completely missing. In the present study, different synthesis times were tested in the obtention of Ag3VO4 crystals by the microwave-assisted hydrothermal method, and their properties were discussed based on experimental results and quantum mechanics simulations. Structural characterizations (XRD, Raman and UV–vis spectroscopy, FE-SEM, and TEM analyses) confirmed the material order at short, medium, and long-range. Theoretical calculations contributed to identifying the atom distribution in the structure, nature of the type of electronic transition, and density of states present in the valence and conduction bands. The topological analysis of the electron density indicated transit chemical interactions and unexpected argentophilic interactions, and Mulliken, Hirshfeld and Bader population analysis provided the charges present on the chemical elements of the crystal. Predicted theoretical surface shapes and their stabilities were evaluated along with FE-SEM images.

Biosynthesis of titanium dioxide nanoparticles using peel extract of Parkia speciosa for methyl orange degradation

Recent research on the biosynthesisof nanoparticles has used plant rather than other biomaterials. In this work, a simpler and environmentally friendly method for the synthesis of titanium dioxide nanoparticles using Parkia speciosa peel extract (P-TiO2 NPs) was carried out. The synthesized TiO2 was characterized by XRD, FESEM, HRTEM, SAED, FTIR, UV-DRS and Zeta analyzer. The XRD and SAED data indicated the crystalline and tetragonal anatase TiO2 phase. HR-TEM and FE-SEM analysis proved that the obtained P-TiO2 had a spherical shape with nano-sized particlesof 8.56 nm. The zeta potential data showed that P-TiO2 was a stable particle. According to the FTIR spectra, the phytochemical components contained in the peel extract were responsible for the reducing and capping agents in TiO2 formation. In addition, the P-TiO2 had photocatalytic activity and completely degraded the methyl orange dye (97.99%). This study shows that the waste of Parkia speciosa could be a potential reducing and capping agents in the synthesis of TiO2 NPs for wastewater treatment.