Nano-scale minerals in-situ supporting CeO2 nanoparticles for off-on colorimetric detection of L–penicillamine and Cu2+ ion

Realizing the high value-added utilization of cheap minerals in environmental catalysis has important practical significance. Herein, four nano-scale minerals, namely halloysite (Hal) nanotubes , palygorskite (Pal) nanorods , and montmorillonite (Mon) and hydrotalcite (LDH) nanosheets , were selected for in-situ supporting CeO 2 nanoparticles (NPs) by a facile one-pot hydrothermal method. Among various nanocomposites (NCs), CeO 2 /Pal behaves the highest peroxidase-like activity, attributing to larger surface area for uniformly dispersing CeO 2 NPs and more exposed active oxygen vacancy (O vac ) defects. A novel off-on colorimetric strategy was constructed for detecting toxic L -penicillamine (LPA) and Cu 2+ ion with limit of detections (LODs) of 8.37 and 9.80 μM, respectively. Density functional theory (DFT) calculations show that the O vac defect on CeO 2 (111) surface can catalyze the heterolytic cleavage of H 2 O 2 into H 2 O and oxygen radical (•O), instead of being two hydroxyl radicals (•OH) on clean surface. It can also act as trapping site for O 2 and H 2 O adsorption, improving the oxygen affinity and hydrophilicity of CeO 2 /Pal. This study provides a feasible strategy for designing mineral-based nanozymes and an insight into the possible catalytic mechanism.