Spectroscopically clean Au nanoparticles for catalytic decomposition of hydrogen peroxide

Au nanoparticles synthesized from colloidal techniques have the capability in many applications such as catalysis and sensing. Au nanoparticles function as both catalyst and highly sensitive SERS probe can be employed for sustainable and green catalytic process. However, capping ligands that are necessary to stabilize nanoparticles during synthesis are negative for catalytic activity. In this work, a simple effective mild thermal treatment to remove capping ligands meanwhile preserving the high SERS sensitivity of Au nanoparticles is reported. We show that under the optimal treatment conditions (250 °C for 2 h), 50 nm Au nanoparticles surfaces are free from any capping molecules. The catalytic activity of treated Au nanoparticles is studied through H₂O₂ decomposition, which proves that the treatment is favorable for catalytic performance improvement. A reaction intermediate during H₂O₂ decomposition is observed and identified.