Bio-fabrication of selenium nanoparticles/micro-rods using cabbage leaves extract for photocatalytic dye degradation under natural sunlight irradiation

This work reports the synthesis of semiconductor selenium nanoparticles/micro-rods (Se-NP/MRs) using the bio-fabrication approach and studies its photocatalytic activity under natural sunlight irradiation. Cabbage leaf extract was used as a reducing agent to fabricate Se-NP/MRs. X-ray diffraction patterns shown the crystalline structure with a crystallite size of 28.17 nm, conferring to planes of hexagonal structure. A characteristic sharp resonance peak in Raman spectra at 235 cm⁻¹ endorsed to the Se – Se bond of crystalline Se-NP/MRs. The prominent peak in the FTIR spectra at 621 cm⁻¹ supported the formation of Se-NP/MRs. Scanning electron micrograph revealed a nearly spherical shape with irregular layers in the 35‒95 nm size range. In contrast, the dimension of the micro-rods was observed to be ~ 10 µm in length and 2.5 µm in diameter. The bandgap energy of Se-NP/MRs was analysed to be 2.14 eV using the Tauc plot. The exciting photocatalytic performance of the bio-fabricated Se-NP/MRs revealed that the methylene blue degradation was ~ 86% in 40 min and ~ 97% in 140 min. Kinetic analysis shows that the pseudo-second-order correlation coefficient is well fitted compared to the pseudo-first-order. Therefore, this work opens the door to further exploration of nano-materials/composites with mixed nanoparticles/micro-rods morphology for sustainable applications in the removal of various textile and industrial contaminants.