Environmental pollution by synthetic dyes and industrial effluent is a serious threat to ecosystems and human health; therefore, the development of effective and sustainable remediation technologies is an urgent priority. This work reports the successful synthesis of SnO₂ nanomaterials through a green synthesizing route using an aqueous extract of Moringa oleifera leaves as a reducing and stabilizing agent. Various structural and morphological studies were performed to confirm the formation of highly crystalline cassiterite SnO₂ with mesoporous, quasi-spherical nanoparticles of high specific surface area. The optical studies indicated a wide bandgap and strong light absorption, suitable for photocatalytic applications. Green-synthesized SnO₂ nanoparticles demonstrated excellent photocatalytic performance with 96% degradation of methylene blue upon visible-light irradiation at a high pseudo-first-order rate constant k = 0.4661 min⁻¹, along with good thermal stability and reusability. DFT calculations were conducted to illustrate the degradation mechanism. The decrease in the HOMO-LUMO energy gap in the case of SnO₂@MB system reflected an increased possibility of charge transfer. Global quantum reactivity descriptors indicated an increased softness and electrophilicity while molecular electrostatic potential, NCI-RDG, and QTAIM analyses demonstrated strong interfacial interactions with partial covalent character. The perfect agreement between experimental and computational results underlines the potentials of green synthesized SnO₂ nanomaterials for efficient dye degradation and advanced optoelectronic applications.
Abbas et al. (Fri,) studied this question.