CO2-Assisted Fabrication of 2D Amorphous CeO2 and Its Application in Photoluminescence Enhancement

Graphical A template- and surfactant-free top-down strategy was developed to transform non-vdW bulk CeO 2 into 2D amorphous CeO 2− x nanosheets with defective structure for the first time by cleaving Ce−O covalent bonds with the assistance of supercritical CO 2 . The unique nanosheets show outstanding UV-vis adsorption and photoluminescence properties due to the disordered atomic structure and increased vacancy defects (F-centers). Two-dimensional (2D) non-van der Waals (non-vdW) amorphous nanomaterials have attracted much attention for optical, catalytic and biomedical applications owing to their rich dangling bonds and unsaturated coordination. CeO 2 , a typical non-vdW material, with amorphous 2D structure and intrinsic optical properties have rarely been prepared via a top-down method due to the lack of anisotropy in its 3D bonding network. Herein, we develop an environmentally-friendly top-down method to achieve ultrathin 2D amorphous CeO 2− x with controllable defects from bulk CeO 2 by utilizing supercritical CO 2 . The unique CeO 2− x nanosheets exhibit outstanding ultraviolet-visible adsorption and photoluminescence (PL) properties due to the disordered atomic structure and increased vacancy defects resulting from the cleavage of Ce−O covalent bonds and amorphization of CeO 2 . In addition, the defect-related emission mechanism of the visible PL for the as-prepared 2D CeO 2− x nanosheets has been proposed.