Threefold enhanced photodegradation of methylene blue using MgO composite with minimum Nd2O3: finding the sweet spot.

Removal of organic dyes like methylene blue (MB) from industrial effluents serves as potential source of potable water. Photocatalytic degradation using sustainable catalyst is deemed to be an affordable solution. In this work, Nd₂O₃/MgO nanocomposite with different compositions (1, 3, and 5wt% Nd₂O₃ with MgO) have been achieved using hydrothermal synthesis and characterized extensively. Interestingly, increasing Nd₂O₃ proportion (1-5%) enhances light absorption, and decreases band gap and electron-hole recombination. The efficacy of the photocatalysts is tested with the degradation of MB dye, through optimizing Nd₂O₃/MgO proportion, contact time, catalyst dose, and pH. Interestingly, control experiments reveal that 5wt% Nd₂O₃/MgO achieve 99.6% degradation of MB in 90 min at pH 7, compared to 88.8% with bare MgO under same condition. Kinetic data show that 5wt% Nd₂O₃/MgO exhibits ca. 3 times higher degradation rate compared to MgO. For the first time, our work enable MgO-based sustainable photocatalyst development with minimum (5 wt%) rare-earth combination to achieve excellent photocatalytic degradation performance.