Fe-doped pyrochlores and defect fluorites as photocatalysts: Efficient dye degradation under visible light irradiation

The increasing global demand for clean and potable water underscores the need for advanced pollutant remediation technologies in wastewater, such as the degradation of azo dyes, which are known to be harmful to human health. To address this issue, heterogeneous photocatalysis emerges as a promising strategy for breaking down recalcitrant molecules. However, efforts are required to develop efficient and stable photocatalysts capable of operating under visible light. This study explores the photocatalytic potential of Fe-doped RE 2 Zr 2 O 7– δ (RE = Pr, Sm, Nd, Y) compositions, synthesized through the microwave-assisted solvothermal method, for the degradation of methylene blue. Characterizations, such as X-ray diffraction (XRD) and Raman spectroscopy, reveal the obtention of single-phase ordered pyrochlore for RE = Pr, Sm and Nd or defect fluorite structures for Y. Photocatalytic tests under visible light demonstrate efficient dye degradation for all Fe-doped samples, Y 2 Zr 1.9 Fe 0.1 O 6.95 (YZF) defect fluorite being the one that exhibits the highest efficiency. Radical scavenging experiments identify hydroxyl radicals as key contributors to the degradation process, along with photoinduced holes. These materials exhibit minimal leaching of iron ions, confirming their stability, and the best material, YZF, demonstrates effective reusability. The results highlight the potential of Fe-doped RE 2 Zr 2 O 7 compositions as an efficient alternative for application as photocatalysts for the degradation of azo dyes under visible light. • Single-phase pyrochlore structures or defect fluorite were obtained using a solvothermal microwave-assisted synthesis method. • Fe doping imparted photocatalytic properties to all prepared compositions. • The Y 2 Zr 1.9 Fe 0.1 O 6.95 (YZF) composition showed the highest degradation efficiency for methylene blue. • Hydroxyl radicals and photoinduced holes played a crucial role in the chromophore degradation process. • All Fe-doped samples exhibited minimal iron leaching, and the YZF demonstrated excellent reusability, highlighting their stability and efficiency.