Cassia fistula -mediated La ₂ O ₃ nanoparticles: a sustainable approach toward high-performance electrochemical and biomedical applications

Biofunctionalized lanthanum oxide nanoparticles (La2O3 NPs) were synthesized using Cassia fistula leaf extract through a simple one-step green method. The synthesized nanoparticles were characterized by UV–Vis, XRD, FT-IR, SEM, EDS, BET, TGA, XPS, CV, and EIS. UV–vis spectra exhibited absorption peaks at 270 and 425 nm, confirming nanoparticle formation. XRD analysis revealed a crystallite size of 36.18 nm for La2O3 NPs, while FT-IR confirmed the presence of phytochemicals responsible for reduction and stabilization. SEM images showed predominantly spherical and well-dispersed particles, and EDS verified elemental composition. XPS analysis confirmed characteristic La 3d and O1s peaks, indicating La³+ oxidation state and metal–oxygen bonding. BET analysis revealed a high surface area of 113.32 m2 g−1 and a mesoporous structure. Electrochemical studies demonstrated enhanced electron transfer at the La2O3 NPs-modified electrode compared with bare GCE. The nanoparticles also exhibited promising antibacterial and antifungal activity, highlighting their potential for biomedical and sensing applications.