Khaled A. Elsayed

With the rapid advancement of flexible electronics and wireless communication technologies, the development of lightweight, high-performance electromagnetic interference (EMI) shielding materials has become critically important. Pulsed laser ablation offers a clean, surfactant-free, and controllable synthesis route for integrating functional nanostructures into polymer matrices for efficient EMI shielding. This study presents a novel approach for fabricating a Bi₂O₃/MWCNTs/CAB flexible polymer via pulsed laser ablation for electromagnetic shielding applications. The developed materials were extensively characterized using different techniques, including X-ray diffraction (XRD), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact angle measurements. The transmission amplitude and complex conductivity in the terahertz frequency range, along with the shielding effectiveness (SE) in the X-band microwave regime, were systematically evaluated. Compared to pure CAB, which showed resonance SE peaks of ∼3 dB at 9.08 GHz and 11.52 GHz, the CNTs/CAB nanocomposite exhibited broadband SE improvements reaching ∼2.7 dB across the X-band. Interestingly, the addition of Bi₂O₃ led to a more uniform but lower SE (∼0.6 dB), suggesting potential for electromagnetic-induced transparency-tunable applications. Given its facile fabrication process and ultrathin structure, the pulsed laser-fabricated MWCNTs/CAB nanocomposite film demonstrates strong potential for next-generation electromagnetic shielding applications.

In this study, seeded zinc oxide (Z-ZnO) thin films were fabricated by a two-step electrochemical deposition process. Different annealing temperatures (300, 400, 500, and 600 °C) were investigated to determine the most effective temperature for the photocatalytic activity. Comprehensive analyses were conducted using X-Ray Diffraction (XRD), scanning electron microscopy (SEM), and UV–visible spectrophotometry. The XRD results confirmed the formation of a wurtzite hexagonal structure, with the highest crystallinity observed at 400 °C. The lowest band gap value, 3.29 eV, was also recorded for Z-ZnO thin film annealed at 400 °C. SEM images revealed that the thin film treated at 400 °C exhibited a well-defined and uniform structure, contributing to its enhanced properties. The photocatalytic efficiency of ZnO (without seeding layer) and Z-ZnO thin films annealed at 400 °C was evaluated through the degradation of tetracycline hydrochloride (TCH) to prove the effect of the presence of a primary seeding layer on ZnO 400 °C thin film efficiency. The degradation efficiency of ZnO thin film without seeding layer was 69.8%. By applying a seeding layer in Z-ZnO 400 °C thin film, the degradation efficiency has been increased to 75.8%. On the other hand, Z-ZnO 400 °C thin film achieved a high degradation efficiency of 82.6% over 300 min in the photoelectrocatalytic system. The obtained Z-ZnO thin films annealed at 400 °C are highly effective photocatalysts and photoelectrocatalysts, offering a significant potential for the degradation of pharmaceuticals and other pollutants in water.

Photocatalysis plays a vital role in addressing environmental challenges by harnessing solar energy for efficient pollutant degradation. In this study, we investigate the photocatalytic activity of a ZnO/g-C₃N₄/ZnS composite system in the degradation of methylene blue, a widely used dye with detrimental effects on aquatic ecosystems. The composite materials were synthesized using a facile and scalable approach, and their structural properties, morphologies, sizes, and elemental compositions were characterized using different analytical techniques. The ZnO/g-C₃N₄/ZnS composite exhibited enhanced photocatalytic performance compared to individual components. Remarkably, the degradation efficiency reached 80% for the composite with a 30% ZnO composition, surpassing the efficiencies of ZnS alone (29%) and ZnS/g-C₃N₄ (65%). The composite’s higher degradation efficiency is due to synergistic semiconductor effects, enhancing charge transfer and reducing electron–hole recombination. ZnO incorporation increases active sites and surface area, improving interaction with methylene blue. The favorable band edge positions of ZnO aligned with ZnS and g-C₃N₄, facilitating the utilization of a broader spectrum of solar light. The composite’s photocatalytic activity was achieved under UV light irradiation, demonstrating its potential for sustainable and energy-efficient applications. This study highlights the significance of composite design and the Z-scheme concept in photocatalysis, offering insights into the development of advanced materials for environmental remediation. The findings contribute to the understanding of efficient solar-driven pollutant degradation and pave the way for the design and optimization of innovative photocatalytic systems for sustainable environmental solutions.

Nanocomposites of SiO₂/MoO₃ having respective weight ratios of 3:1, 2:2, and 1:3 were synthesized using a nanosecond pulsed laser ablation method. The prepared samples were analyzed with UV–Vis and Raman spectroscopy, XRD, SEM, EDX, and TEM. Based on the TEM analysis, the morphology and the structure of the nanocomposites varied with the change in the ratio of MoO₃, and the sample containing the highest amount of MoO₃ shows a compact morphology and a higher number of nanoparticles. The band gap energy of the nanocomposites increases with an increase in MoO₃ load. The nanocomposites were used in the catalytic reduction of 4-nitrophenol (4-NP) in the presence of NaBH₄. The reduction time of 4-NP decreases as the amount of MoO₃ increases in the nanocomposite. The rate constants were estimated at 0.0878, 0.2319, and 0.1726 min⁻¹ for SiO₂/MoO₃ (3:1, 2:2, and 1:3) catalysts respectively. The results demonstrate the good catalytic performance of the prepared materials by enabling fast reduction of 4-NP.

Gold nanoparticles (AuNPs) and carbon nanotubes (CNTs) are increasingly being investigated for cancer management due to their physicochemical properties, low toxicity, and biocompatibility. This study used an eco-friendly technique (laser synthesis) to fabricate AuNP and Au/CNT nanocomposites. AuNPs, Au/CNTs, and CNTs were tested as potential cancer nanotherapeutics on colorectal carcinoma cells (HCT-116) and cervical cancer cells (HeLa) using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. In addition, the non-cancer embryonic kidney cells HEK-293 were taken as a control in the study. The cell viability assay demonstrated a significant reduction in cancer cell population post 48 h treatments of AuNPs, and Au/CNTs. The average cell viabilities of AuNPs, Au/CNTs, and CNTs for HCT-116 cells were 50.62%, 65.88%, 93.55%, and for HeLa cells, the cell viabilities were 50.88%, 66.51%, 91.73%. The cell viabilities for HEK-293 were 50.44%, 65.80%, 93.20%. Both AuNPs and Au/CNTs showed higher cell toxicity and cell death compared with CNT nanomaterials. The treatment of AuNPs and Au/CNTs showed strong inhibitory action on HCT-116 and HeLa cells. However, the treatment of CNTs did not significantly decrease HCT-116 and HeLa cells, and there was only a minor decrease. The treatment of AuNPs, and Au/CNTs, on normal HEK-293 cells also showed a significant decrease in cell viability, but the treatment of CNTs did not produce a significant decrease in the HEK-293 cells. This study shows that a simplified synthesis technique like laser synthesis for the preparation of high-purity nanomaterials has good efficacy for possible future cancer therapy with minimal toxicity.