Structural, optical, dielectric and antibacterial studies of Mn doped Zn0.96Cu0.04O nanoparticles

Antimicrobial, antioxidant, cytotoxicity and photocatalytic performance of Co doped ZnO nanoparticles biosynthesized using Annona Muricata leaf extract

In the present study, ZnO nanoparticles doped with 3%, 5% and 7% of cobalt have been synthesized by green method using Annona muricata leaf extract. The obtained nanopowder was characterised by XRD, FTIR, XPS, HRTEM, SAED, SEM, EDAX and UV-Visible spectroscopy techniques. XRD patterns confirm the formation of pure and Co doped ZnO nanoparticles with a hexagonal wurtzite structure with high phase purity. FTIR spectra indicate the stretching vibration of Zn-O at 495 cm-1. The incorporation of Co2+ ions into the ZnO lattice was identified by XPS analysis. EDX spectra confirm the existence of Co, Zn and O elements. The SEM and HRTEM micrographs show morphology of nanoparticles. The optical study specifies a decrease in energy band gap with an increase in Co-doping concentration. The photocatalytic performance of ZnO and Zn0.93Co0.07O has been examined for the degradation of methylene blue (MB) under sunlight irradiation. The antimicrobial activity of synthesized nanoparticles against s.aureus, p.aeruginosa, b.subtilis bacterial strains c.albicans and a.niger fungal strains as investigated. The Zn0.93Co0.07O nanoparticles exhibit good antioxidant properties. Moreover, the cytotoxicity of ZnO nanoparticles was evaluated against L929 normal fibroblast cells. So, this work suggests that Annona muricata leaf extract mediated pure and Co-doped ZnO nanoparticles are a potential candidate for biomedical and photocatalytic applications.

Efficient Up-Conversion ZnO Co-Doped (Er, Yb) Nanopowders Synthesized via the Sol-Gel Process for Photovoltaic Applications

In this study, undoped and (Erbium, Ytterbium) co-doped ZnO nanopowders were prepared using the sol-gel method and the supercritical drying of ethyl alcohol. Doping ZnO nanopowders were elaborated with 5 mol% of Er (5 Er: ZnO), 5 mol% of Er and 5 mol% of Yb (5 Er, 5 Yb: ZnO), and 5 mol% of Er and 10 mol% of Yb (5 Er, 10 Yb: ZnO) concentrations. The effects of the Yb concentration on the structural, morphological, photoluminescent, and electrical properties of the ZnO nanopowders were investigated. The main findings of this work were the crystallinization of all of the nanopowders in a hexagonal Wurtzite structure with a spheroidal morphology and a size of 60 nm. Hence, the doping concentration would affect the crystallinity and the morphology of the ZnO nanopowder. The UC (Up-Conversion) emissions were investigated under a 980 nm excitation. It was observed that (Er, Yb: ZnO) exhibited green, ranging between 525 nm and 550 nm and red up-converted emissions of 655 nm, due to the efficient energy transfer process between Er³⁺ and Yb³⁺. The absolute quantum yield percentage (QY %) of the doped nanopowders was measured as a function of power density at each up-converted emission. This would prove that (5 Er, 5 Yb: ZnO) had the highest QY percentage value of 6.31 ± 0.2% at a power density of 15.7 W/cm². Additionally, it had the highest excited state lifetime for green and red emissions. Moreover, the Hall effect measures showed that the resistivity decreased while the electron mobility increased after doping, suggesting that most of rare earth ions were located in the interstitial positions. The carrier concentration increased after doping until (5 Er, 5 Yb: ZnO), suggesting that the Zn²⁺ ions substituted the RE³⁺ ions. Then, the carrier concentration decreased, suggesting that doping with higher concentrations would cause grain boundary defects. These findings would suggest that (5 Er, 5 Yb: ZnO) would have the best electrical properties and the lowest band gap energy (3.24 eV). Therefore, the presented preparation of the (Er, Yb: ZnO) nanopowders elaborated, using the sol-gel process would be a potential interesting material for UC applications.

Phyto Synthesis of Manganese-Doped Zinc Nanoparticles Using Carica papaya Leaves: Structural Properties and Its Evaluation for Catalytic, Antibacterial and Antioxidant Activities

The current study aims to synthesize bimetal oxide nanoparticles (zinc and manganese ions) using the carica papaya leaf extract. The crystallite size of the nanoparticle from X-ray diffraction method was found to be 19.23 nm. The nanosheet morphology was established from Scanning Electron Microscopy. Energy-dispersive X-ray diffraction was used to determine the elemental content of the synthesized material. The atomic percentage of Mn and Zn was found to be 15.13 and 26.63. The weight percentage of Mn and Zn was found to be 7.08 and 10.40. From dynamic light scattering analysis, the hydrodynamic diameter and zeta potential was found to be 135.1 nm and −33.36 eV. The 1,1-diphenyl-2-picryl hydroxyl radical, hydroxyl radical, FRAP, and hydrogen peroxide scavenging tests were used to investigate the antioxidant activity of Mn-Zn NPs. Mn-Zn NPs have substantial antioxidant properties. The photocatalytic activity of the Mn-Zn NPs was assessed by their ability to degrade Erichrome black T (87.67%), methyl red dye (78.54%), and methyl orange dye (69.79%). Additionally, it had significant antimicrobial action S. typhi showed a higher zone of inhibition 14.3 ± 0.64 mm. Mn-Zn nanoparticles were utilized as a catalyst for p-nitrophenol reduction. The bimetal oxide Mn-Zn NPs synthesized using C. papaya leaf extract exhibited promising dye degradation activity in wastewater treatment. Thus, the aforementioned approach will be a novel, low cost and ecofriendly approach.

The effect of Mn and Co dual-doping on the structural, optical, dielectric and magnetic properties of ZnO nanostructures

This paper addresses the effect of Mn (2%, fixed) and Co (2, 4, and 6%, varied) substitution on the structural, optical, dielectric and magnetic responses of ZnO nanoparticles synthesized by the co-precipitation chemical route. The X-ray diffraction analysis confirms the hexagonal wurtzite structure of ZnO. The incorporation of co-doping in the ZnO host, indicated by peak shifting in the XRD patterns, enhanced the crystallite size of the Mn/Co dual-doped ZnO nanoparticles. The FTIR spectra show a characteristic peak around 875 cm⁻¹ assigned to Zn–O stretching, this validates the formation of the wurtzite structure of ZnO. Raman spectroscopy reveals the characteristic band of the wurtzite structure of ZnO nanoparticles along with coupled vibration modes of Mn/Co with the donor defect states in the doped samples. Enhanced optical absorption in the visible region and a significant red-shift in the absorption band edge were found due to doping. The optical band gap is found to decrease from 3.45 eV to 3.15 eV when Co doping increases up to 6%. The dielectric properties, strongly frequency-dependent, decrease with increasing Co doping while the electrical conductivity increases. Ferromagnetism is observed in all the doped samples, and its origin is attributed to an increase in oxygen vacancies which form bound magnetic polarons. It can be inferred that the doping of Mn and Co can be an effective tool to tune the physical properties of ZnO nanoparticles for potential spintronics and high-frequency applications.

This paper addresses the effect of Mn (2%, fixed) and Co (2, 4, and 6%, varied) substitution on the structural, optical, dielectric and magnetic responses of ZnO nanoparticles synthesized by the co-precipitation chemical route.

Hierarchically Porous Cu-, Co-, and Mn-Doped Platelet-Like ZnO Nanostructures and Their Photocatalytic Performance for Indoor Air Quality Control

Several parameters, including specific surface area, morphology, crystal size, and dopant concentration, play a significant role in improving the photocatalytic performance of ZnO. However, it is still unclear which of these parameters play a significant role in enhancing the photocatalytic activity. Herein, undoped and Mn-, Co-, and Cu-doped platelet-like zinc oxide (ZnO) nanostructures were synthesized via a facile microwave synthetic route, and their ultraviolet (UV) and visible-light-induced photocatalytic activities, by monitoring the gaseous acetaldehyde (CH₃CHO) degradation, were systematically investigated. Both the pure and doped ZnO nanostructures were found to be UV-active, as the CH₃CHO oxidation photocatalysts with the Cu-doped ZnO one being the most UV-efficient photocatalyst. However, upon visible light exposure, all ZnO-nanostructured samples displayed no photocatalytic activity except the Co-doped ZnO, which showed a measurable photocatalytic activity. The latter suggests that Co-doped ZnO nanostructures are potent candidates for several indoor photocatalytic applications. Various complementary techniques were utilized to improve the understanding of the influence of Mn-/Co-/Cu-doping on the photocatalytic performance of the ZnO nanostructures. Results showed that the synergetic effects of variation in morphology, surface defects, that is, V_O, high specific surface areas, and porosity played a significant role in modulating the photocatalytic activity of ZnO nanostructures.

High responsivity and 1/f noise of an ultraviolet photodetector based on Ni doped ZnO nanoparticles

This study involves the novel fabrication of a high responsivity, fast response, and low-cost (UV) photodetector (PD) based on ZnO/Ni nanoparticles deposited on a glass substrate.