Plasma Discharge Inside Liquid: A Novel Single-step Green Approach to Fabricate Metal/Metal Oxide Nanocomposites

This report focuses on a novel method to synthesize metal/metal oxide nanocomposites (NC) by generating plasma between two vertically pointed electrodes inside liquid. The method combines two well-known approaches of nanofabrication, such as evaporation of electrode material and reduction of metallic salt, to fabricate NCs in a single step. As both the electrode and metallic salt solution serve as the source of nanoparticles (NP), therefore it provides flexibility in controlling both the physical (plasma, electrode material) and chemical (solution) parameters, which facilitates fine-tuning required for desired shape and composition of NPs. Moreover, it is an environmentally friendly approach as it does not require any toxic stabilizing and reducing agents, which is a major concern in chemical nanofabrication methods. Based on the potential applications of Au/CuO NC, we have synthesized the same by generating plasma between two copper electrodes inside HAuCl₄ solution. The energetic electrons and reactive species present in the plasma zone enable the simultaneous synthesis of CuO nanospindles and spherical Au NPs. Interestingly, the Au NPs bind the CuO nanospindles forming flower-like structures. The process can be utilized to fabricate a wide range of desired NCs.