Figure 6.

Schematic diagram of catalytic mechanisms of carbon-based nanozymes. (a) Schematic illustration of the process of N-CDs enhanced Fenton system which was used for the sensitive and selective determination of Fe²⁺ ion (CL as chemiluminescence). Reprinted with permission from ref. [74]. Copyright 2019 Elsevier; (b) Catalytic mechanism of the g-C₃N₄ nanosheets (NSs)-H₂O₂-TMB system. From left to right: H₂O₂ molecules interact with g-C₃N₄ NS to generate ^•OH and ^•OH oxidize TMB to form a blue product TMBox. Reprinted with permission from ref. [78]. Copyright 2017 American Chemical Society; (c) Schematic diagram of enzyme-like activities of N-doped porous carbon nanospheres (N-PCNSs). N-PCNSs perform four enzyme-mimicking activities: oxidase (OXD), peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) for ROS regulation. Reprinted from ref. [79].