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.