Synthesis and characterizations of Ce₂Zr₂O₇–TiO₂ for increased photocatalytic activity toward degradation of methylene blue

Herein, novel Ce₂Zr₂O₇–TiO₂ was synthesized by the green method using Annona Squamosa L. peels extract (ASE). ASE contains alkaloids as hydrolyzing and capping agents for the formation of Ce₂Zr₂O₇–TiO₂. Various characterizations were conducted to elucidate the vibrational, optical, structural, morphological, elemental composition and photocatalytic properties of Ce₂Zr₂O₇–TiO₂. The photocatalytic activity of TiO₂, Ce₂Zr₂O₇, and Ce₂Zr₂O₇–TiO₂ was evaluated for methylene blue degradation under irradiated visible light. The degradation percentage using Ce₂Zr₂O₇–TiO₂ was higher than that of both TiO₂ and Ce₂Zr₂O₇. TiO₂ modification with Ce₂Zr₂O₇ increased the photocatalytic activity due to the increased light absorption in the visible region and a low electron-hole recombination rate. The reaction kinetics of methylene blue degradation over Ce₂Zr₂O₇–TiO₂ was found to be a pseudo-first-order rate with k_app value of = 1.1 × 10⁻² min⁻¹, which was around 4-fold higher than that of TiO₂. Importantly, this research suggests the preparation of a novel TiO₂-based photocatalyst with good photoresponse in the visible region for potential water treatment application.