Color tunable carbon quantum dots from wasted paper by different solvents for anti-counterfeiting and fluorescent flexible film

Currently, the disposal of municipal wastes (paper, plastic, and coffee residue) is a problem due to increasing the amount of municipal wastes, global environmental problems, and high disposal cost. Here, we report the synthesis of carbon quantum dots from waste paper by different solvents by a conventional hydro-/solvothermal method for solving the environmental and disposal problems. The carbon quantum dots synthesized with waste papers have several advantages such as low toxicity, low cost, and eco-friendly. The prepared carbon quantum dots have main emission peak from 440 to 540 nm under 340-480 nm excitation. The prepared carbon quantum dots can be applied to easily prepare anti-counterfeiting ink and fluorescent flexible film because of their unique optical property and excellent chemical and photostability.