Bismuth nickelate nanoparticles synthesized using Curcuma longa rhizome extract as biocidal and photocatalytic agents

Perovskite-type metal oxides have sparked intense attention owing to their diverse structural, electrical, and catalytic characteristics, making them interesting materials for environmental and biological applications. In this study, Curcuma longa (turmeric) rhizome extract was used as a natural reducing and stabilizing agent to prepare bismuth nickelate nanoparticles (BiNiO₃ NPs) using a green manufacturing method. Significant visible light absorption was shown by UV-visible absorption spectroscopy (UV-Vis), which confirmed its photocatalytic application with a predicted band gap of 2.90 eV. X-ray diffraction (XRD) confirmed the morphological and structural properties of the resultant nanoparticles and revealed a highly crystalline multiphase perovskite phase consisting of tetragonal (ICDD #96-900-8427) and cubic (ICDD #96-901-3981). The presence of phytochemicals generated from turmeric on the surface of the nanoparticles was confirmed by Fourier-transform infrared spectroscopy (FTIR), by revealing a broadband between 550 and 650 cm^-1. The existence of quasi-spherical, rod-like, and pear-shaped nanoparticles with an average particle size of around 15-20 nm was shown by investigations using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). The elemental composition was authenticated by energy-dispersive X-ray spectroscopy (EDX) by affirming the characteristic peak of O 1s at 529.79 eV. Zone of inhibition investigations confirmed that the BiNiO₃ NPs possess strong antibacterial efficacy against Staphylococcus aureus (21.33 mm) and Escherichia coli (22.66 mm). Furthermore, Rhodamine-B (Rh-B) dye was effectively degraded by photocatalytic studies when exposed to visible light, with 93.82% degradation occurring in 100 min. The reduced band gap, surface phytochemical capabilities, and efficient charge separation inside the nanoparticles are the causes of the ensuing enhanced activity. This study demonstrates the potential of turmeric-assisted green-synthesised BiNiO₃ NPs as a multipurpose substance for antibacterial and wastewater purification applications, offering a sustainable substitute for conventional chemical synthesis methods.