Enhancement of visible light adsorption and photocatalytic degradation activity of organic dye by coating semiconducting TiO2 shell on plasmonic Au particles

The plasmonic effect enhances light absorption in semiconductor photocatalysts, while the noble metal-semiconductor interface promotes charge carrier transfer and separation, boosting photocatalytic activity. However, current methods for synthesizing metal-core TiO ₂-shell nanoparticles face challenges, such as keeping stable and preventing aggregation. This study presents a simple and moderate synthesis method for Au@TiO ₂ core-shell nanoparticles, enabling precise control over the TiO ₂ shell thickness and stable photocatalytic performance. Various characterization techniques were employed to assess the optical and structural properties of the synthesized Au@TiO ₂ core-shell nanostructures. The results demonstrated that increasing the Au core concentration led to a gradual decrease in TiO ₂ shell thickness. The adsorption properties and photocatalytic degradation efficiency of the synthesized Au@TiO ₂ core-shell nanostructured catalysts were thoroughly examined, particularly focusing on their performance with methyl orange (MO) and methylene blue (MB). Au@TiO ₂ achieved excellent adsorption performance for MO, with a maximum capacity of 231±6 mg/g. Furthermore, Au@TiO ₂ exhibited higher photocatalytic degradation activity of both MO and MB than pure TiO ₂. The mechanism study indicated that it attributed to enhanced visible light absorption, reduced bandgap, and higher valence band energy. Additionally, the Au@TiO ₂ catalysts showed good cyclic stability, making them promising for future applications. This research offers insights into designing efficient photocatalysts, addressing existing synthesis challenges, and contributing valuable references for future advancements.