ZnO Au Nanoparticles Research Articles

Plasmonic ZnO-Au Nanocomposites: A Synergistic Approach to Enhanced Photocatalytic Activity through Nonthermal Plasma-Assisted Synthesis

A novel and efficient method for synthesizing Au-decorated ZnO nanoparticles (NPs) with enhanced photocatalytic activity is presented. The synthesis involves a two-step process: hydrothermal preparation of ZnO NPs followed by nonthermal plasma-assisted deposition of Au nanoparticles on their surface. Comprehensive characterization of the ZnO and ZnO–Au NPs was carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Optical properties were evaluated via UV-Vis absorption and fluorescence measurements. The synthesized ZnO NPs displayed a hexagonal wurtzite structure, and the successful deposition of Au NPs was confirmed by TEM and XPS analysis, along with Raman and fluorescence data showing the quenching effect caused by Au. The incorporation of Au nanoparticles led to the appearance of localized surface plasmon resonance (LSPR) at 540 nm, enhancing visible light absorption and improving photocatalytic performance. Notably, the methylene blue (MB) degradation efficiency increased from 78% with pure ZnO NPs to 91.6% with ZnO–Au NPs under UV-Vis irradiation, demonstrating superior photocatalytic activity. This study introduces a simple and scalable method for synthesizing plasmonic ZnO-Au hybrid nanomaterials using plasma technology and highlights the critical role of Au NPs in enhancing photocatalytic performance by reducing electron–hole recombination.

Formation and Evaluation of Au/ZnO Particles by a Spray Pyrolysis Method

ZnO/Au is expected to exhibit catalytic properties by absorbing ultraviolet and visible light because ZnO and Au nanoparticles can absorb ultraviolet and visible light, respectively. Doping studies on Au nanoparticles on ZnO (ZnO/Au) have been conducted to expand the absorption wavelength range. This study generates ZnO/Au particles by an ultrasonic spray pyrolysis method (USP). To prevent particle aggregation, Triton X-100, a non-ionic surfactant, is added, and its effects are examined. The generated ZnO/Au particles are characterized using different methods. SEM reveals the particle size is several micrometers, while XRD analysis indicates that ZnO and a metallic Au crystalline are present. The TEM images of the particles show that the Au crystals are well dispersed in the inner and outer portions of ZnO. UV-Vis spectroscopy confirms that the smaller the Au particle size, the higher the visible absorption peak near 400 nm. Adding Triton X-100 shifts the absorption peak toward the longer wavelength side but improves the aggregation of Au particles.

Synergistic Antibacterial Activity of Nanohybrid Materials ZnO–Ag and ZnO–Au: Synthesis, Characterization, and Comparative Analysis of Undoped and Doped ZnO Nanoparticles

ZnO nanoparticles (NPs) were prepared using the hydrothermal method, and then doped with Ag or Au NPs, yielding ZnO NPs, ZnO–Ag NPs, and ZnO–Au NPs, which were characterized by transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The synthesized nanomaterials were analyzed for their antibacterial properties against bacterial strains (Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Salmonella typhi) by qualitative and quantitative assays. Minimal inhibitory concentration (MIC) results show that growth control is more effective for Gram-positive bacteria than for Gram-negative bacteria. Although ZnO NPs and Ag NPs are antibacterial agents, the lowest bacterial growth was observed for ZnO–Ag NPs, showing that the doped Ag NPs greatly facilitate the interaction between the microbial cells and the NP surface. Though the same antibacterial effect was expected for ZnO–Au NPs, the inhibition activity was very close to that of ZnO NPs. The order of bacterial cell growth inhibition was ZnO–Ag NPs >> ZnO–Au NPs ~ ZnO NPs >> ZnO powder. We also analyzed the morphology of bacterial cells treated with NPs by scanning electron microscopy.