Plasma-driven 1D to 2D nanomaterial phase transition

Abstract

The increasing demand for novel nanomaterials in nanotechnology requires innovative techniques to adapt their properties and morphologies, highlighting the importance of strategies for controlled conversions between different material morphologies. This research reveals a unique plasma-assisted anion-exchange phase transformation which facilitates the conversion from 1D model of copper oxide nanowires into 2D copper sulfide. Our investigation reveals that plasma-assisted sulfurization triggers the onset of 2D structure evolution from the original nanowire, followed by the complete conversion of the original 1D copper oxide into 2D copper sulfide. This dimensionality transformation is likely driven by the accumulation of surface charges in the plasma environment, particularly increased in regions of heightened curvatures in the nascent copper sulfide phase. The enhanced electric field in these zones directs the flow of charged plasma species to these specific regions. In addition, the preferential adsorption of sulfur species at the edges of the nanoplates drives the diffusion of copper ions from the core of the nanowires outward to the edges of the forming nanoplates, where sulfurization predominantly occurs. These suggestions were supported by theoretical modeling of the processes. The morphology of the transformed nanowires depends on the original diameter of the nanowires and the duration of the treatment. Finally, the study highlights the potential of plasma-assisted techniques for advanced processing of nanomaterials, enabling precise and distinct nanomodifications.