Veeramani Mangala Gowri

This study aims to enhance the photocatalytic degradation of phenol under UV light by synthesizing a silver–zinc oxide/reduced graphene oxide (Ag–ZnO/rGO) hybrid composite via a hydrothermal method. Structural and optical characterizations confirmed the successful incorporation of Ag and rGO into the ZnO matrix, leading to improved light absorption and efficient charge separation. Photocatalytic tests revealed that the Ag–ZnO/rGO hybrid composite showed superior activity, degrading 76.16% of phenol in just 12 h, significantly higher than Ag–ZnO (65.66%) and pure ZnO (31.78%). After 24 h, it achieved 98.91% degradation. Kinetic analysis confirmed its enhanced performance, showing the highest pseudo-first-order rate constant (k = 0.1883 h^–1) among all samples. This improvement is attributed to the synergistic effects of Ag and rGO, which promote efficient charge separation and faster degradation kinetics. The enhanced photocatalytic efficiency is attributed to the surface plasmon resonance (SPR) effect of Ag nanoparticles (NPs) and the excellent electron transport properties of rGO, which collectively suppress charge carrier recombination. These findings highlight the promising potential of Ag–ZnO/rGO as a high-performance photocatalyst for environmental remediation and wastewater treatment applications.

Polymer–nanofiller interfaces unite selective pollutant enrichment, efficient charge transfer, and catalytic signal amplification. Critical design and deployment priorities support reliable, portable environmental monitoring.

This study investigates the synthesis and characterization of Fe–ZnO/GO composites aimed at enhancing magnetic characteristics and improving the photocatalytic degradation of organic contaminants. Reflux condensation was used to synthesize Fe-doped ZnO, which was then mixed with graphene oxide (GO) to form a composite. Energy-dispersive X-ray spectroscopy and electron microscopy demonstrated homogeneous Fe–ZnO dispersion on GO sheets. In contrast, a structural study using X-ray diffraction confirmed the wurtzite phase of ZnO, with peak changes indicative of Fe integration. UV–visible spectroscopy demonstrated an expanded absorption range and a reduced bandgap of 2.76 eV in Fe–ZnO/GO compared to 3.06 eV in ZnO. Photoluminescence studies showed decreased electron–hole recombination due to GO’s electron-accepting properties. The Fe–ZnO/GO composite outperformed Fe–ZnO (97.46%) and ZnO (58.16%) in terms of photocatalytic degradation efficiency for Rhodamine B under UV light, achieving 99.32% degradation within 24 h. A first-order rate constant of 0.2093 h^–1, 5.80 times greater than ZnO, was found via kinetic analysis. The combined effects of GO for improved charge separation and reactive oxygen species generation, and Fe doping for enhanced light absorption, were attributed to the superior performance. Vibrating sample magnetometry confirmed the ferromagnetic behavior of Fe–ZnO/GO, with a saturation magnetization of 7.69 × 10^–4 emu/g. This indicates that the material can be easily separated using a magnetic field, which is beneficial for recycling and reuse. The enhanced photocatalytic activity, structural stability, and reusability make Fe–ZnO/GO a promising candidate for environmental remediation. However, further improvement in its visible-light response and long-term stability is needed for large-scale water treatment applications.

The present investigation examined how substituting some Cu²⁺ ions for Zn²⁺ ions could increase zinc oxide (ZnO) photocatalytic activity toward the reduction of Rhodamine B. Phase composition, the presence of functional groups, optical properties, emission spectra, and surface morphology of ZnO nanoflakes (NFs) were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-visible spectroscopy (UV-vis), photoluminescence (PL) spectrophotometer, and scanning electron microscopy (SEM). To investigate the photocatalytic capabilities of Cu-doped ZnO NFs driven by visible light/sunlight, Rhodamine B dyes were photocatalytically degraded in water using UV-visible absorption spectroscopy. Using Williamson-Hall analysis of the XRD data, it was discovered that the internal strain of the Cu-doped ZnO NFs was altered. UV-vis absorption showed that the energy gap of the semiconducting ZnO NFs shrank when Cu was substituted. FT-IR studies revealed that the surface of the Cu-doped ZnO NFs contained greater amounts of reactive oxidizing species. PL studies revealed that the ZnO NFs' surface defects were being caused by the Cu substitution. According to SEM research, more surface fault NFs formed when the concentration of Cu increased. The photocatalytic activity was enhanced by the production of these NFs. The UV-vis absorption spectra showed that Cu-doped ZnO NFs were more effective than pure ZnO at degrading the rhodamine B dye (RhB). Finally, it was shown that replacing Zn²⁺ ions with Cu²⁺ ions improved the photodegradation of the rhodamine B dye. According to this study, Cu-doped ZnO NFs are an excellent choice for wastewater treatment.

Chemical polymerization/oligomerization opens numerous opportunities, from fundamental materials research to practical applications in catalysis, energy, sensing, and medicine. The electrochemical detection of vitamins B₉ (folic acid) and C (ascorbic acid) requires new approaches because of low selectivity, electrode fouling, and interference from other chemicals. As an excellent material for long-term vitamin detection, oligo 3,5-diamino-1,2,4-triazole (oligo DAT) enhances the sensitivity, selectivity, and stability of sensors by creating a stable, conductive layer that facilitates electron transfer and reduces interference from common substances like glucose or uric acid. This work investigates the electrochemical sensing properties of oligo DAT, utilizing hydrogen tetrachloroaurate (III) (HAuCl₄) as an oxidizing agent at ambient temperature for the concurrent and sensitive detection of vitamins B₉ and C. The oligo DAT was carefully characterized by spectroscopic and microscopic techniques to confirm its structure and properties. The GC electrode was subsequently connected to the oligo DAT by a potentiodynamic technique. The oligo DAT-modified electrode exhibited higher catalytic activity than the unmodified GC electrode for the oxidation of vitamins B₉ and C. This led to the determination of the sensitivity levels for both vitamins; the lowest measured concentration for vitamin C was 1 × 10^-11 M with a theoretical limit of detection (LOD) of 1.9 × 10^-11 M, and for vitamin B₉, the lowest measured concentration was 1 × 10^-11 M with a theoretical LOD of 3.5 × 10^-11 M. The practical efficacy of this straightforward method was proven by the quantification of vitamins B₉ and C in human plasma samples.