Sensor heavy metal from natural resources for a green environment: A review relation between synthesis method and luminescence properties of carbon dots

Carbon dots (CDs) are 10‐nm nanomaterial classes as excellent candidates in various applications: physics, biology, chemistry, and food science due to high stable biocompatibility and high surface expansive. CDs produced from natural materials have received wide attention due to their unique benefits, easy availabilities, sufficient costs, and harmless to the ecosystem. The various properties of CDs can be obtained from various synthesis methods: hydrothermal, microwave‐assisted, and pyrolysis. The CDs have shown enormous potential in metal particle detection, colorimetric sensors, electrochemical sensors, and pesticide sensors. This review provides systematic information on a synthesis method based on natural resources and the application to the environmental sensors for supporting the clean environment. We hope this review will be useful as a reference source in providing the guidance or roadmap for new researchers to develop new strategies in increasing luminescence properties CDs for multi detection of heavy metals in the environment. This review article provides information of the advantages and disadvantages of synthesized carbon dots (CDs) by hydrothermal, microwave‐assisted, and pyrolysis, and their CDs properties. It covers the type of CDs, mechanism of metal ion sensing and colorimetric which depend on the CDs size. It provides information that will help new researchers as a roadmap for future technological challenges to develop highly efficient and effective environmental sensors.