Cerium-Based Nanozyme Functionalized by Conducting Polymers with Dual Enzyme Activities for Intelligent Colorimetric Sensing of Hexavalent Chromium

Conducting polymers (CPs) have emerged as a class of promising organic conducting materials and attracted extensive attention due to their intrinsic electrical conductivity and easy synthesis process. New design strategies to enhance the catalytic activity of nanozymes by CP functionalization would be highly desirable. Herein, we report the fabrication of CPs-functionalized cerium-based nanozymes and study their application in the intelligent colorimetric sensing of Cr (VI). The CPs are innovatively modified on the copper-doped cerium oxysulfate cluster (CuCe) by <i>in situ</i> surface polymerization, which is conducive to the directed growth of CPs and the effective contact with CuCe. As anticipated, the polythiophene-functionalized CuCe (PTh-CuCe) exhibits excellent oxidase-like and laccase-like catalytic activities owing to the well-matched energy band structure and high photoinduced hole-electron separation efficiency. Relying on the stable chelation ability between 8-HQ and Cr (VI), PTh-CuCe is successfully used to fabricate an 8-HQ-mediated intelligent platform for Cr (VI) sensing, with the limit of detection as low as 0.026 μM. This study provides an effective design strategy to develop nanozymes with excellent catalytic performance. Our newly developed nanozyme-based sensing platform can serve as a powerful tool for the intelligent sensing of Cr (VI) in water samples, holding great potential for environment monitoring.