Rosemary leaves extract mediated green synthesis of silver functionalized BiFeO3 nanoparticles with improved visible light photocatalytic performance

Silver-functionalized bismuth ferrite (Ag-BFO) nanoparticles were successfully synthesized via a rosemary (Rosmarinus officinalis) leaf extract–assisted green route and demonstrated markedly enhanced visible-light photocatalytic performance. Structural analyses confirmed the formation of a rhombohedral perovskite BiFeO₃ phase with effective Ag incorporation and suppressed secondary phases. Ag functionalization reduced the optical bandgap from 2.11 to 2.07 eV and significantly increased the BET surface area from 1.86 to 9.35 m2 g⁻1, promoting improved light absorption and charge separation. Under visible-light LED irradiation, Ag-BFO achieved 95% degradation of methylene blue dye within 120 min, compared to 75% for pristine BFO under identical conditions. Kinetic studies revealed a pseudo-first-order behavior with a higher rate constant for Ag-BFO. Scavenger experiments identified hydroxyl radicals (•OH) as the major reactive species. The enhanced photocatalytic activity is attributed to Ag-induced bandgap narrowing, increased surface area, and suppressed charge-carrier recombination. These findings demonstrate that rosemary-mediated green synthesis of Ag functionalized BFO as an effective strategy for developing high-performance photocatalysts for sustainable wastewater treatment.