Figure 1.

(a) Nanozyme sensor arrays based on heteroatom-doped graphene for detecting pesticides. Reprinted with permission from Ref. [28]. Copyright 2020 ACS; (b) The fabrication principle of H–GNs paper-based colorimetric sensor. Reprinted with permission from Ref. [32]. Copyright 2019 Elsevier. (c) Principle of the detection of Pb²⁺ on graphene/Fe₃O₄-Au NPs sensing platform. Reprinted with permission from Ref. [34]. Copyright 2020 MDPI. (d) Schematic illustration of oligonucleotide-based colorimetric sensor for Hg²⁺ detection using smart interface of GO/Au NPs. Reprinted with permission from Ref. [35]. Copyright 2021 Elsevier.