Polymeric Schiff base assisted synthesis of Fe-N-C MFs single-atom nanozymes for discrimination and intelligent sensing of tannic acid

Developing colorimetric sensors based on nanozymes for the detection of targets have gained significant importance. Herein, a simple, sensitive and effective colorimetric sensor based on Fe and N co-doped microflowers (Fe-N-C MFs) nanozymes was developed for the detection of tannic acid (TA). Fe-N-C MFs nanozymes with atomically dispersed Fe-Nx active sites have been fabricated by the template and polymeric Schiff base assisted synthesis method. Under optimized operational conditions, a colorimetric sensor based on the oxidase mimic activity of Fe-N-C MFs was developed for sensitive detection of TA with the response range (0.2–50 µM) and low detection limit (0.15 µM). Meanwhile, Fe-N-C MFs nanozymes can realize the detection of TA by the “Thing Identify” application installed on a smartphone. Moreover, the sensor arrays composed of Fe-N-C MFs and the control sample can effectively identify and discriminate TA in mixed samples. This work revealed the feasibility of fabrication of Fe-N-C single-atom nanozymes based on polymeric Schiff base and flower-like template for the detection and discrimination of TA.