Contact-Electro-Catalysis Enables Ultrasonic Synthesis of Gold Nanoparticles at Water–PTFE Interfaces

The synthesis of gold nanoparticles (AuNP) using sustainable methods remains a significant challenge in nanotechnology. Traditional approaches often rely on toxic chemicals or complex procedures, leading to unavoidable environmental concerns. Herein, a novel, environmentally friendly method for preparing AuNP via contact-electro-catalysis (CEC) driven by ultrasonication at the water–dielectrics interfaces is presented. This strategy eliminates the need for external chemical reducing agents, making it a sustainable alternative for nanoparticle production. Under ultrasonic stimulation at 40 kHz and 150 W, polytetrafluoroethylene (PTFE) transfers electrons to AuCl₄⁻ ions, effectively reducing them to elemental gold. The mean size of AuNP increases from 74 to 220 nm as ultrasonication duration extends from 1 to 20 min, highlighting the impact of contact duration on nanoparticle growth. A comparative study of dielectric materials, including Nylon-6, polyvinylidene difluoride, and PTFE, reveals that PTFE with its higher electron affinity greatly outperforms other materials in facilitating the electron transfer necessary for the synthesis of AuNP. Additionally, the presence of H₂O₂ generated during the process also contributes to the reduction, further boosting AuNP synthesis. Herein, it offers insights into the influence of dielectric materials on CEC efficiency, providing a promising, scalable, and green alternative for nanoparticle production.