Highly Active CoRh Graphitic Nanozyme for Colorimetric Sensing in Real Samples

Rh-based nanozymes show high catalytic efficiency, specificsurfacearea, good stability, and unique physicochemical properties, whilemagnetic nanozymes facilitate the magnetic separation of detectionsamples under an external magnetic field for improved sensitivity.However, magnetic Rh nanozymes, especially those with excellent stability,have not been reported. Herein, we apply the chemical vapor deposition(CVD) method to prepare a CoRh graphitic nanozyme (termed as CoRh@Gnanozyme), which structurally consists of CoRh nanoalloy encapsulatedby a few layers of graphene for sensitive colorimetric sensing applications.The proposed CoRh@G nanozyme has superior peroxidase (POD)-like activity,and it shows higher affinity of the CoRh@G nanozyme than horseradishperoxidase (HRP) toward 3,3 ',5,5 '-tetramethylbenzydine(TMB) oxidation. In addition, the CoRh@G nanozyme shows high durabilityand superior recyclability owing to its protective graphitic shell.The outstanding merits of the CoRh@G nanozyme allow its use for quantitativecolorimetric detection of dopamine (DA) and ascorbic acid (AA), showinghigh sensitivity and good selectivity. Moreover, it shows satisfactoryperformance for AA detection in commercial beverages and energy drinks.The proposed CoRh@G nanozyme-based colorimetric sensing platform showsgreat promise in point-of-care (POC) visual monitoring.

Automated summary

In this study, a magnetic CoRh@G nanozyme with high catalytic efficiency, unique physicochemical properties, and excellent stability was successfully synthesized and used for sensitive colorimetric sensing of dopamine and ascorbic acid. The CoRh@G nanozyme showed superior peroxidase-like activity and high affinity towards 3,3',5,5'-tetramethylbenzydine oxidation.