Synthesis of ultrathin CeO₂ nanosheets for enhanced electrocatalytic degradation of 17-alpha-ethynylestradiol

An ultrathin two-dimensional cerium dioxide (2D-CeO₂) structure was accomplished using a unique combination of template and ion exchange strategies. When employed in the electrochemical degradation of 17-alpha-ethynylestradiol (EE2) in aqueous solutions, the as-prepared 2D-CeO₂ performed considerably better than CeO₂ nanoparticles (CeO₂-NPs) and commercial CeO₂ (C-CeO₂). Structure, morphology and composition of all three materials (i.e., 2D-CeO₂, CeO₂-NPs and C-CeO₂) were characterized and analyzed comparatively by X-ray diffractometer, transmission electron microscopy, scanning electron microscopy, Raman, electron paramagnetic resonance and X-ray photoelectron spectroscopy. Owing to its 2D structure and abundant active sites, 2D-CeO₂ performed better in the electrochemical degradation system of EE2. The catalytic activity of the material was evaluated while studying the effects of EE2 concentration, various electrolyte amounts, current density, and pH of the solution on the degradation. The results indicate that the reaction rate constant of EE2 on 2D-CeO₂ was as good as 0.028, and EE2 can be degraded by 97.64% after 140 min under optimized conditions. While the reaction rate constants of CeO₂-NPs and C-CeO₂ were only 0.016 and 0.012, and the degradation rates were 88.65% and 80.41%, respectively. Further, the catalytic performance of 2D-CeO₂ was examined using cyclic voltammetry, linear scanning voltammetry, electrochemical impedance spectroscopy and chronopotentiometry. In addition, the mechanism of electrocatalysis was investigated through a combination of hydroxyl radical generation and quenching experiments, as well as density functional theory analysis. Overall, this ultrathin 2D-CeO₂ could be a promising candidate in the field of electrochemical degradation of environmental endocrine disrupting chemicals.