Unveiling the Synthesis, Characterization, and Multifunctional Applications of Ca₅(PO₄)₃F@Ca₅P₈ Nanocomposites From Phosphate Waste for Antioxidant Activity and Evans Bleu Decomposition

Abstract This study explores the innovative synthesis and versatile applications of Ca₅(PO₄)₃F@Ca₅P₈ nanocomposites (NCs), crafted from phosphate waste sourced from Djebel Onk, Algeria, advancing sustainable material use and environmental remediation. FTIR analysis unveiled distinct functional groups, including C─H, P─H, P─O, and F─Ca, underscoring the material's chemical richness, while XRD revealed a crystalline architecture blending hexagonal (Ca₅(PO₄)₃F) and monoclinic (Ca₅P₈) phases, with a precise crystallite size of 22.45 ± 1.18 nm. SEM and EDS showcased uniform spherical particles averaging 24 nm, brimming with Ca, P, O, and F elements. Optical properties dazzled with peak absorption at 391 nm, direct and indirect bandgaps of 1.62 and 2.98 eV, and an Urbach energy of 0.435 eV, signaling exceptional UV–visible absorption capabilities. Beyond its structural elegance, the nanocomposite exhibited remarkable antioxidant prowess, neutralizing nearly 100% of hydrogen peroxide, and delivered striking photocatalytic performance, degrading 99.2% of Evans Blue dye in just 140 min (rate constant 0.01334 min −1 ). Antibacterial assays further highlighted its potency, effectively combating S. aureus , C. albicans , and other microbes. These compelling results position Ca₅(PO₄)₃F@Ca₅P₈ NCs as a multifunctional powerhouse for water treatment, photocatalysis, and antibacterial applications, paving the way for sustainable technological breakthroughs.