Nanomaterials

This study explores the sustainable synthesis of zinc oxide (ZnO) from industrial waste and its application in removing water contaminants such as chloramphenicol (CAP), metronidazole (MNZ), and prometryn (PROM). ZnO synthesized from zinc production waste (ZnO(2)) exhibited competitive photocatalytic performance compared to commercial ZnO (ZnO(1)), achieving 79% CAP degradation (Kd = 0.53 × 10⁻² min⁻¹) and 72% MNZ degradation (Kd = 0.43 × 10⁻² min⁻¹) under UV light, while showing higher activity in PROM degradation (32% removal) due to its mesoporous structure. Although ZnO(2) had a slightly lower specific surface area (24.9 m²/g) and pore volume (0.26 cm³/g) than ZnO(1), it demonstrated significant environmental and economic benefits by repurposing industrial waste. Catalytic tests in ethanol oxidation revealed ZnO(2) required higher temperatures for full conversion but exhibited higher acetaldehyde selectivity (70%). These findings highlight the potential of waste-derived ZnO as a sustainable alternative for water treatment and catalytic processes, aligning with circular economy principles and reducing reliance on natural resources.

Silica nanostructures are attractive platforms for hybrid nanomaterials because of their chemical stability and versatile surface functionalization. Here, spherical SiO₂ nanoparticles were synthesized by a modified Stöber method, functionalized with (3-aminopropyl)triethoxysilane (APTES), and decorated with gold nanoparticles (AuNPs) formed using an inorganic stabilization strategy involving OH⁻ and Cl⁻ ions, without conventional organic AuNP capping agents. Complementary characterization by Fourier-transform infrared spectroscopy (FTIR), ultraviolet–visible diffuse reflectance spectroscopy (UV–VIS DRS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) supported the sequential surface modification and formation of the SiO₂–APTES–AuNPs hybrid material. TEM yielded average diameters of 100.81 ± 1.74 nm for SiO₂ nanoparticles (n = 50) and 2.00 ± 0.31 nm for supported AuNPs (n = 80). Methylene blue (MB) was subsequently used for a proof-of-concept Raman evaluation. At 10⁻³ and 10⁻⁴ M MB, relative Raman signal-amplification ratios of approximately 7.5 and 3.5, respectively, were obtained from the integrated response near 1620 cm⁻¹; these values are not conventional surface-enhanced Raman scattering (SERS) enhancement factors. At 10⁻⁶ M, a fluorescence-like background was observed without establishing metal-enhanced fluorescence. Density functional theory calculations using an Au₃₂ cluster provided qualitative insight into local S···Au and π···Au interactions. Overall, these results establish an inorganic SiO₂-AuNPs as a physicochemically characterized hybrid nanomaterial prepared through an inorganic AuNP-stabilization strategy and support its further investigation in Raman-based applications.

Fe-based amorphous alloys are attractive for microwave attenuation because they combine soft-magnetic behavior, relatively high electrical resistivity compared with compositionally similar crystalline alloys, and flexible structural design. A persistent challenge is to achieve strong attenuation and broad bandwidth at a small matching thickness without relying on complex multiphase architectures. Fe₈₅P₉C₂B₂Si₂ amorphous powders were prepared by pulse-discharge atomization and the fine spherical fraction was subsequently flattened by controlled wet-ball milling. The atomized powders remain predominantly amorphous, whereas milling produces high-aspect-ratio microflakes together with localized approximately 5 nm band-like heterogeneous regions containing limited nanocrystalline order. Relative to the spherical powders, FP5 shows stronger dielectric and magnetic responses. At 16.9 GHz and a thickness of 1.7 mm, the attenuation constant reaches 235.9 m⁻¹ and the normalized input-impedance magnitude is 0.999, indicating that strong intrinsic attenuation coincides with nearly ideal impedance matching. FP5 consequently exhibits a minimum reflection loss of −53.5 dB and an effective absorption bandwidth of 6.2 GHz (11.8–18.0 GHz) at 1.85 mm. The results indicate that the high-aspect-ratio morphology is the better-supported primary structural contribution to the improved absorption, while local amorphous/nanocrystalline heterogeneity may provide an additional contribution.