Nanoscale modification of one-dimensional single-crystalline cuprous oxide

In this work we report for the first time a method to modify the surface of Cu₂O nanowires in a controllable way and physically weld them into a network form, which contributes to higher electrical conductivity as well as a strong water-repelling nature. We have used state-of-the-art theoretical calculations to support our experimental observations. We demonstrate how varying the irradiation fluence can modulate the surface and decorate the nanowire with a uniform distribution of Cu₈O nanocrystals due to preferential sputtering. While several well studied joining techniques are available for carbon and metal-based nanowires, the same information for ceramic nanowires is scarce at present. The current study sheds light into this and a state-of-the-art 3D simulation technique predicts most of the modifications including surface modulation, oxygen depletion and welding. The welded network shows higher electrical conductivity than the unwelded assembly. With Cu₂O being of p-type the current ion beam joining technique shows a novel path for fabricating p-i-n junctions or solar cell devices through bottom-up approach. Furthermore, we have explored the response of this network to moisture. Our calculation based on density functional theory predicts the hydrophilic nature of individual copper oxide nanowires both before and after irradiation. However, the network shows a strong water-repelling nature, which has been explained quantitatively using the Cassie-Baxter model.