A Detailed Insight into the Effects of Morphologies of Cerium Oxide on Fenton‐like Reactions for Different Applications

Abstract As an exceptional Fenton‐like reagent, cerium oxide (CeO 2 ) finds applications in biomedical science and organic pollutants treatment. The Fenton‐like reaction catalyzed by CeO 2 typically encompasses two distinct processes: one resembling the classical Fenton reaction, wherein cerium (Ce 3+ ) triggers the decomposition of hydrogen peroxide (H 2 O 2 ) to yield reactive oxygen species (ROS), and the other involves the complexation of H 2 O 2 on the Ce 3+ surface, leading to the formation of peroxides. However, the influence of diverse CeO 2 morphologies on these two reaction pathways has not been comprehensively explored. In this study, CeO 2 exhibiting three typical morphologies, rods, cubes, and spheres, were prepared. The generation of ROS and peroxides was evaluated using the 3,3,5,5‐tetramethylbenzidine (TMB) oxidation reaction and the reduction current of H 2 O 2 , respectively. Moreover, the impacts of pH variations and CeO 2 /H 2 O 2 concentrations on the production and conversion of these two reaction products were investigated. To corroborate the distinctions between the resultant products and their applicability, apoptosis assays and acid orange 7 (AO7) degradation analyses were performed. Notably, CeO 2 rods exhibited the highest proportion of Ce 3+ , predominantly engaging in complexation with H 2 O 2 to foster peroxide formation, thereby facilitating the robust degradation of AO7. However, the generated peroxides appeared to occupy Ce 3+ sites, thereby impeding the H 2 O 2 decomposition process. Conversely, Ce 3+ species on the surface of CeO 2 cubes were primarily involved in H 2 O 2 decomposition, leading to heightened ROS production, and thus showcasing substantial potential for damaging A549 tumor cells. It is worth noting that the ability of these Ce 3+ species to form peroxides through complexation with H 2 O 2 was comparatively reduced. In summation, this study sheds light on the intricate interplay between distinct CeO 2 morphologies and their divergent impacts on Fenton‐like reactions. These findings expand our comprehension of the influences on its reactivity of CeO 2 morphologies and open new insights for applications in diverse domains, from organic dye degradation to tumor therapy.