Élaboration de nanofils de silicium par gravure chimique assistée par un métal : caractérisation et application en photocatalyse hétérogène de l’oxyde de graphène, du chrome (VI) et de la rhodamine B

Abstract

We have elaborated silicon nanowires by metal-assisted chemical etching. The different experimental parameters affecting the process such as the etching temperature, the resistivity of the substrates and the crystalline defects introduced by ion implantation have been investigated. Moreover, we have studied the morphology and optical properties of silicon nanowires decorated by metal nanoparticles obtained by chemical deposition method. Then, the photocatalytic properties of hydrogenated crystalline silicon nanowires, silicon nanowires decorated with metal nanoparticles and silicon nanowires decorated by metal nanoparticles coated with reduced graphene. We found that silicon nanowires decorated with copper nanoparticles (SiNFs/CuNPs) are the most effective substrates for the photocatalytic reduction of graphene oxide than hydrogenated silicon nanowires (SiNFs-H) and silicon nanowires decorated with silver nanoparticles (SiNFs/AgNPs). Furthermore, the performance of these substrates for the reduction of Cr(VI) under visible light irradiation has been evaluated. We found that hydrogenated silicon nanowires (SiNFs-H) substrate alone was not sufficient for the reduction of chromium (VI). However, the addition of organic acids allowed the reduction of Cr(VI) under visible light irradiation. However, SiNFs decorated with copper nanoparticles allowed the reduction of Cr (VI) to Cr (III) under visible light irradiation without organic additives. While for the photodegradation of rhodamine B, hydrogenated silicon nanowires are more effective under visible irradiation provided they are deoxidized after 90 min of irradiation. The deposition of reduced graphene on the silicon nanowires surface improved significantly the photocatalytic activity.