Ultrasonic Activation of Au Nanoclusters/TiO₂: Tuning Hydroxyl Radical Production Through Frequency and Nanocluster...

This study explores the sonocatalytic activity of gold nanoclusters (Au NCs) combined with titanium dioxide (TiO₂) nanoparticles, forming Au NCs/TiO₂ composites. The hybrid material significantly enhances hydroxyl radical (•OH) generation under ultrasonic conditions, attributed to high-energy cavitation bubbles formed during ultrasonication. The effects of frequency (200, 430, and 950 kHz) and power were systematically evaluated on Au₁₄₄/TiO₂ composites, identifying 430 kHz as optimal for •OH production due to its efficient cavitation energy. Au₁₄₄ NCs function as electron traps, reducing electron-hole recombination in ultrasonically activated TiO₂, thereby improving charge separation and enhancing •OH generation. Size-dependent effects were also studied, showing an efficiency trend of Au₁₄₄ > Au₂₅ > plasmonic Au nanoparticles > bare TiO₂. These findings highlight the importance of ultrasonication frequency and Au NC size in optimizing sonocatalytic performance in the Au NCs/TiO₂ composites, providing valuable insights for designing advanced sonocatalysts with applications in chemical synthesis, environmental remediation, and biomedical fields.