Tailoring photocatalytic performance of ZnTiO3 via Gd and Pr doping: a multi-scale structural and optical study

ZnTiO3 nanoparticles were synthesized and modified with Gd and Pr dopants to enhance their photocatalytic activity. Rietveld refinement of XRD data verified a hexagonal ZnTiO3 structure for all samples, along with a reduction in crystallite size from 30 nm for the undoped material to 24 nm for the co-doped sample due to lattice strain induced by rare-earth incorporation. UV–Vis studies showed a red shift in the absorption edge, with the optical bandgap decreasing from 2.39 eV to 2.18 eV, indicating improved light utilization. FESEM analysis revealed finer particle distribution and increased surface roughness upon doping. Photocatalytic evaluation using methylene blue degradation under UV light demonstrated that efficiency improved from 60% for pure ZnTiO3 to 89% for Gd@Pr@ZnTiO3. The performance enhancement is attributed to better charge separation, higher defect density, and a greater number of active sites created by co-doping. These findings confirm that rare-earth modification is a promising strategy for developing efficient ZnTiO3-based photocatalysts for wastewater treatment.