The role of surface modification over ZnCrCe-layered double hydroxide on the enhancing of the photodegradation of organic pollutants by layered double hydroxide-derived mixed metal oxides

The ZnCrCe-mixed metal oxide catalyst (ZnCrCe-MMO) was synthesized through the thermal treatment of ZnCrCe-Layered Double Hydroxides (ZnCrCe-LDHs) precursors. The LDH precursor underwent surface modifications via two distinct methods: acid etching and alkali etching, followed by calcination, resulting in the formation of ZnCrCe-MMO-A and ZnCrCe-MMO-B respectively. These modifications were evaluated for their impact on the photodegradation efficiency of organic pollutants, specifically methylene blue dye (MB) and tetracycline antibiotic (TC). The confirmation of synthesis of the catalysts, along with their physicochemical and electrochemical properties, were thoroughly investigated using a variety of analytical techniques, including XRD, FT-IR, FE-SEM, TGA, BET, HR-TEM, XPS, DRS, ICP, Raman analysis, EDS, and Mott-Schottky analysis. This study reports, for the first time, the photocatalytic degradation of methylene blue and tetracycline pollutants using the ZnCrCe-MMO-A and ZnCrCe-MMO-B catalysts. Furthermore, the formation of intermediate oxidative species (O2̇⁻) during the photocatalytic reactions was identified using various quenchers, and a potential mechanism for the process was proposed. The results indicate that the ZnCrCe-MMO-B catalyst demonstrates superior efficiency in the photocatalytic removal of pollutants. This research elucidates the effects of metal vacancies on the photodegradation process and offers a promising approach for achieving highly efficient photodegradation of organic pollutants.