Optical Study of Redox Behavior of Silicon Nanoparticles Induced by Laser Ablation in Liquid

The redox behavior of silicon nanoparticles (Si-nps), produced by laser ablation in liquid, was studied based on the optical measurements of Si colloidal solution after addition of noble metal salts. It was found that such prepared Si-nps can reduce Au3+ ions quickly, in contrast to the conventional microsized Si powders which are very stable in the noble metal ion solutions. Also, the Si-nps can reduce Ag+ ions, which should not occur according to the overall redox potentials of the ion solutions and bulk Si. Such reductive behaviors were attributed to the fresh surface of the Si-nps prepared by laser ablation in liquid and size-induced positive redox potentials for the system containing silicon and metal salts. This study could be beneficial to deepen the understanding of physical/chemical behaviors of Si-nps and important in the control of the chemical stability of the particles. Importantly, due to the nontoxic properties of Si and Si oxide, the reductive Si-nps have demonstrated the potential applications in pollution remediation of heavy metal ions, like reduction of Cr6+ or Hg2+, in wastewater or soil, in addition to the optical and electronic industry.