Dual-functional Au–TiO2 nanoparticles: enhanced photocatalytic activity and Pickering emulsion stabilization for wastewater treatment

Abstract

This study explores the synthesis, characterization, and application of Au–TiO₂ hybrid nanoparticles (NPs) as photocatalysts and Pickering emulsifiers for wastewater treatment. Two types of Au–TiO₂ composites were prepared: core–shell Au–TiO₂ and preformed Au-adsorbed on titania. The photocatalytic activity of these nanoparticles was evaluated under UV and visible light irradiation using 4-propylbenzoic acid as a model organic pollutant. The results demonstrated the prominent role of Au in enhancing the photocatalytic efficiency of TiO₂ nanoparticles, with core–shell Au nanoparticles exhibiting excellent performance due to improved electron transfer and reduced band gap energy. In parallel, the potential of Au–TiO₂ nanoparticles as Pickering emulsifiers was assessed. Freeze-dried particles achieved the highest emulsion stability, attributed to their optimal size and intermediate wettability. Similarly, the adsorption of gold nanoparticles on titania proved to be an effective strategy for modifying particle wettability without compromising the photodegradation rate. These findings highlight the dual functionality of Au–TiO₂ nanoparticles, combining effective pollutant degradation with robust emulsion stabilization, advancing their applicability in environmental remediation.