Photoelectrocatalytic activity of silicon nanowires decorated with electroless copper nanoparticles and graphene oxide using a plasma jet for removal of methyl orange under visible light

Abstract

Silicon nanowires (Si_NWs) have been studied due to their interesting properties, such as light trapping and catalytic activity for removing organic molecules. In this work, silicon nanowires are decorated with copper (Si_NWs-Cu_NPs), graphene oxide (Si_NWs-GO), and both copper and graphene oxide GO (Si_NWs-Cu_NPs-GO). They were prepared and tested as photoelectrocatalysts to remove the azoic dye methyl orange (MO). The silicon nanowires were synthesized by the MACE process using HF/AgNO₃ solution. The decoration with copper nanoparticles was made by galvanic displacement reaction utilizing a copper sulfate/HF solution, while decoration with GO was achieved using an atmospheric pressure plasma jet system (APPJ). The as-produced nanostructures were then characterized by SEM, XRD, XPS, and Raman spectroscopy. Cu(I) oxide was generated during the decoration with copper. Cu(II) oxide was produced when Si_NWs–Cu_NPs were exposed to the APPJ. GO was successfully attached on the surface of silicon nanowires and silicon nanowires decorated with copper nanoparticles. The photoelectrocatalytic activity of silicon nanostructures was tested under visible light, leading to an MO removal efficiency of 96% within 175 min with Si_NWs–Cu_NPs-GO, followed by Si_NWs-Cu_NPs, Si_NWs-GO, undecorated Si_NWs, and bulk silicon.