Functionalized carbon dots from natural precursors for environmental remediation and renewable energy technologies

The green synthesis of functionalized carbon dots (C-dots) from natural precursors is reviewed, providing a sustainable and versatile platform for environmental remediation and renewable energy technologies. The focus is on methods such as hydrothermal, microwave-assisted, pyrolytic, solvent-based, and ultrasonic routes, with an emphasis on biomass-derived precursors and green solvents. Strategies are given for surface passivation, hybridization, and composite formation to tailor their optical properties and their applications in sustainable technologies are examined. In environmental remediation, they act as efficient photocatalysts for degrading organic pollutants and reducing carbon dioxide (CO2). For renewable energy, they improve light-harvesting in solar cells and dye-sensitized solar cells. Their notable stability and efficiency are highlighted, alongside persistent challenges in controlling their size, uniformity, and scalability of quantum yield. Future work must clarify the structure-activity relationships for multifunctional compounds, facilitating commercial deployment.