Spectroscopic analysis of nanosized Zn(Ag, Ni)O systems and observation of superparamagnetism at low temperature.

To understand the impact of binary doping in ZnO, nanosized Zn(Ag, Ni)O systems were synthesized by the sol-gel method. The amount of Ag was fixed at 2 at%, and that of Ni was varied from 1 to 15 at%. Ni incorporation equal to or beyond 3 at% gave rise to the development of the NiO phase. The presence of Ag and Ni did not have much influence on the lattice constants of ZnO. However, a larger addition of Ni impacted the unit cell of NiO, as indicated by the reduction of the lattice constant of NiO. The increase in NiO and Ag contents in ZnO reduced the second and third harmonic intensities under non-linear investigations. X-ray photoelectron spectroscopy analysis indicated that initial Ni addition varied randomly along with Ag, and it stabilized itself at higher concentration. Field emission scanning electron microscopy revealed that interlinked particles and chains with tamarind shapes were formed, closely matching the rod-like structures under high resolution. Ag and Ni addition altered the structures slightly and randomly till 5 at% Ni; thereafter they deviated from the particle shape to flat disc-shapes. Interestingly, the magnetic response of the sample was determined by the NiO phase, and the effect of Ni and Ag substitution in the ZnO host matrix was almost irrelevant at low temperatures toward magnetic contribution. Weak ferromagnetism at low temperatures (≤50 K) with superparamagnetic-like behavior (cusp in ZFC magnetization) was observed in all the samples. This could be attributed to the finite nano-size effect and uncompensated spins at the surface of the particle.

An Eco-Friendly Synthesis Approach for Enhanced Photocatalytic and Antibacterial Properties of Copper Oxide Nanoparticles Using Coelastrella terrestris Algal Extract.

Background: In the current scenario, the synthesis of nanoparticles (NPs) using environmentally benign methods has gained significant attention due to their facile processes, cost-effectiveness, and eco-friendly nature. Methods: In the present study, copper oxide nanoparticles (CuO NPs) were synthesized using aqueous extract of Coelastrella terrestris algae as a reducing, stabilizing, and capping agent. The synthesized CuO NPs were characterized by X-ray diffraction (XRD), UV-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and field emission scanning electron microscopy (FE-SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). Results: XRD investigation revealed that the biosynthesized CuO NPs were nanocrystalline with high-phase purity and size in the range of 4.26 nm to 28.51 nm. FTIR spectra confirmed the existence of secondary metabolites on the surface of the synthesized CuO NPs, with characteristic Cu-O vibrations being identified around 600 cm-1, 496 cm-1, and 440 cm-1. The FE-SEM images predicted that the enhancement of the algal extract amount converted the flattened rice-like structures of CuO NPs into flower petal-like structures. Furthermore, the degradation ability of biosynthesized CuO NPs was investigated against Amido black 10B (AB10B) dye. The results displayed that the optimal degradation efficacy of AB10B dye was 94.19%, obtained at 6 pH, 50 ppm concentration of dye, and 0.05 g dosage of CuO NPs in 90 min with a pseudo-first-order rate constant of 0.0296 min-1. The CuO-1 NPs synthesized through algae exhibited notable antibacterial efficacy against S. aureus with a zone of inhibition (ZOI) of 22 mm and against P. aeruginosa with a ZOI of 17 mm. Conclusion: Based on the findings of this study, it can be concluded that utilizing Coelastrella terrestris algae for the synthesis of CuO NPs presents a promising solution for addressing environmental contamination.

Asterarcys quadricellulare algae-mediated copper oxide nanoparticles as a robust and recyclable catalyst for the degradation of noxious dyes from wastewater.

The present article explores the synthesis of copper oxide nanoparticles (CuO NPs) utilizing Asterarcys quadricellulare algal extract and examines the effect of various reaction parameters on the size and morphology of the nanoparticles. The samples were thoroughly characterized using XRD, FTIR, UV-vis, FE-SEM, and EDS techniques. The XRD analysis disclosed that the size of the synthesized nanoparticles could be controlled by adjusting the reaction parameters, ranging from 4.76 nm to 13.70 nm along the highest intensity plane (111). FTIR spectroscopy provided evidence that the phytochemicals are present in the algal extract. We have compared the photocatalytic activity of biologically and chemically synthesized CuO NPs and observed that biologically synthesized CuO NPs showed better photocatalytic activity than chemically synthesized CuO NPs. The biosynthesized CuO NPs (S8) demonstrated outstanding photodegradation activity towards four different organic dyes, namely BBY, BG, EBT, and MG, with degradation percentages of 95.78%, 98.02%, 94.15%, and 96.04%, respectively. The maximum degradation efficacy of 98.02% was observed for the BG dye at optimized reaction conditions and 60 min of visible light exposure. The kinetics of the photodegradation reaction followed the pseudo-first-order kinetic model, and the rate constant (k) was calculated using the Langmuir-Hinshelwood model for each dye. This study provides an efficient and sustainable approach for synthesizing CuO NPs with superior photocatalytic degradation efficiency towards organic dyes.

Spectroscopic investigation of Cux Mg0.2-x Zn0.8 S (x = 0, 0.05, 0.10, 0.15) thin films for deep and dilute blue LED applications.

The effect of copper (Cu) doping on the luminescent properties of the spray deposited Mg0.2 Zn0.8 S thin films were investigated for the first time. The Mg0.2 Zn0.8 S film is an excellent luminescent material with strong blue emissions. In the current investigation, we doped Mg0.2 Zn0.8 S with Cu by taking (Cu + Mg) as 20 at% by keeping other element ratios constant. Among the different samples in the series, Cu0.05 Mg0.15 Zn0.8 S has shown promising results with dark blue emission. Also, these films showed good structural formation with lower or no other impurities, which is evident from the X-ray diffraction (XRD). Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) confirmed the improved material quality of Cu0.05 Mg0.15 Zn0.8 S as compared to the pristine. Raman and X-ray photoelectron spectroscopy (XPS) studies have been carried out for the samples. Various defects induced in the films were investigated by recording the photoluminescence (PL) spectra and Cu:(Mg0.2 Zn0.8 S) films exhibited the capability to produce dilute blue luminescence by absorbing ultraviolet (UV) light. The Cu0.05 Mg0.15 Zn0.8 S film showed promising material property, which is suitable for light-emitting diode (LED) applications.