Synthesis of Low-Bandgap Perovskite-Like Magnesium Zirconate (MgZrO₃) Nano-Sponges for Enhanced Visible-Light Photocatalytic Degradation of Nile Blue Dye

Photocatalytic degradation using perovskite oxides presents a sustainable solution for wastewater treatment, yet challenges such as wide bandgaps and inefficient charge separation limit their practical application. This study reports a facile green synthesis of low-bandgap magnesium zirconate (MgZrO 3 ) nano-sponges via a solvothermal method using clove oil as a deep eutectic solvent, followed by calcination at 600 °C. Structural and morphological characterization through XRD and SEM confirmed the formation of a mixed-phase MgO–ZrO 2 system with a unique nano-sponge morphology, offering a high surface area for photocatalytic reactions. Optical analysis via UV-Vis DRS revealed a reduced bandgap of 3.1 eV compared to conventional MgZrO 3 (4–4.5 eV), enabling efficient visible-light absorption. The photocatalytic performance of MgZrO 3 was evaluated through the degradation of Nile blue dye under visible-light irradiation, achieving over 80% degradation within 6 hours. Kinetic studies demonstrated pseudo-first-order reaction behavior with a rate constant of 0.00616 min -1 . The enhanced activity is attributed to the material’s low bandgap, effective charge separation, and abundant active sites. A mechanistic study proposed the generation of reactive oxygen species (·OH, ·O 2 -1 ) as key contributors to dye degradation. This work highlights the potential of eco-friendly MgZrO 3 nano-sponges as efficient visible-light photocatalysts for industrial wastewater treatment, while the green synthesis approach aligns with sustainable nanomaterial production. Further optimization of surface properties and defect engineering could advance its applications in solar-driven environmental remediation.