Photocatalysis of silicon nanowires decorated with metallic nanoparticles and graphene oxide under different light intensities

Abstract

This work shows silicon nanowires (SiNWs), decorated with different nanoparticles, as a photocatalytic material under different lighting conditions. In this system, the comparison between different materials and the influence of light intensity on their performances are studied. On the other hand, the synthesis of SiNWs was done by a metal-assisted chemical etching. The decoration with nanoparticles of copper CuNPs and cuprous oxide CuO2NPs was conducted with the electroless technique. Graphene oxide (GO) lamellar particles passing through an atmospheric pressure plasma (APPJ) were instantaneously ionized losing OH radicals and connecting them into a continuous coating around the SiNWs nanostructures. Such a layer with a large contact area among SiNWs/GO/Cu/CuO2 was obtained with a small thickness of about 10–20 nm. This is proposed to allow and increase charge carrier transference to the aqueous solution for redox reactions to degrade the dye molecules. Through statistical analysis, we compared the percentages of the decrease in methyl orange concentration used to measure the photocatalytic performance. SiNWs – CuNPs surfaces, in combination with high-intensity light, exhibit higher degradation percentages and rate constants. The graphene oxide coatings were deposited on monocrystalline silicon wafers and silicon nanowires, constituting a semiconductor-semiconductor heterojunction. This is an innovation proposed in this work that could lead to the fabrication of semiconductor heterojunctions with Z-scheme complementarity.