Influence of Phthalein dyes on structural, optical, and sensing properties of zinc oxide supported Silica-titania nanocomposite

Abstract

Owed to rapid responsive pH sensing attributes, the zinc-supported Silica-titania (Z/ST) nanocomposite is synthesized by the sol-gel method. Three distinct pH dyes such as phenolphthalein, creosol red, and phenol red are immobilized in Z/ST to examine their influence on the structural and optical properties of Z/ST nanocomposite. Microscopic analyses possessed that Z/ST and dyes immobilized Z/ST have crack-free porous morphology. The phenol red immobilized Z/ST (P-Z/ST) has a low surface roughness ∼0.5 nm, ultra-thin coating ∼2.1 nm, and more hydrophilic features than C-Z/ST (creosol red immobilized Z/ST), and HPh-Z/ST (phenolphthalein immobilized Z/ST). The P-Z/ST possessed 0.3 s against pH 12 and pka 10, C-Z/ST shows a time response 0.5 s and pka (negative log of the acid dissociation constant) value around 8, while Hph-Z/ST revealed a time response 0.68 s and high pka around 11. All three nanocomposites attributed stable and fast responses in basic media.