Facile green synthesis of lanthanum oxide nanoparticles using Centella Asiatica and Tridax plants: Photocatalytic, electrochemical sensor and antimicrobial studies

Lanthanum oxide (La2O3) nanoparticles (NPs) were prepared by the facile green combustion method using the leaf powders of Centella asiatica and Tridax plants (C-La2O3 and T-La2O3 NPs). Various analytical and electrochemical techniques were employed to understand the morphology, crystallinity, and band gap of La2O3 NPs. X-ray diffraction (XRD) studies revealed that the NPs exists in a hexagonal crystal structure with a crystallite size of 20 nm. The morphological studies (SEM and TEM) revealed La2O3 clusters with porous structures. UV-DRS (diffuse reflectance) spectra was used to arrive at the band gap of 5.44 eV and 5.61 eV for C-La2O3 and T-La2O3 NPs. The thermogravimetric studies showed a 2-step decomposition process involving La(OH)3. Electrochemical and photocatalytic studies were conducted to explore the efficiency of C-La2O3 and T-La2O3 NPs. The better photocatalytic degradation was observed for T-La2O3 NPs with 60% efficiency. In addition, La2O3 NPs also exhibited good antimicrobial activities.