Elucidation of photocatalytic degradation mechanism of an organic pollutant based on Gd2−xTi2−xFexO7 nanomaterials under simulated visible lightN. H. AlonizanEur. Phys. J. Plus, 137 6 (2022) 715DOI: https://doi.org/10.1140/epjp/s13360-022-02919-w