Formation of human hair-Ag nanoparticle composites via thermal and photo-reduction: A comparison study

Hair-silver nanoparticle (Ag NPs) composites were fabricated using a green one- or two-step process through a combination of heat treatment with thermal or UV reduction. In the one-step process, untreated hair was thermally reduced in the range of 250−450 °C after Ag ion adsorption, resulting in a partial oxidation of Ag. In the two-step process, the Ag ions were thermally reduced using heat-treated hair as starting material for the Ag ion adsorption to exclude the partial oxidation of Ag during the formation of hair/Ag NP composites. In an alternative two-step process, hair/Ag NP composites were prepared by reducing the heat-treated hair using UV irradiation. The crystalline structure and oxidation state of the Ag NPs in the hair/Ag NP composites was analyzed via X-ray photoelectron spectrometry (XPS) and X-ray diffractometry (XRD). The results indicate that the two-step process with heat pre-treatment of hair effectively generated pure Ag NPs in the composites. The catalytic activity of the hair/Ag NP composites was investigated with UV–vis spectrophotometry using the degradation reaction of methylene blue (MB). The hair/Ag NP composites can potentially be applied for the treatment and purification of dye pollutants.