From synthesis to applications: Exploring the potential of graphene quantum dots in water treatment

Graphene Quantum Dots (GQDs) are emerging carbon-based nanomaterials that have attracted significant attention for water purification due to their high surface area, tunable bandgap, excellent adsorption capacity, and photocatalytic activity. Despite their potential, challenges such as synthesis variability, environmental instability, unclear ecological impacts, and difficulties in scalable manufacturing limit their practical application. Addressing these issues and understanding GQDs-pollutant interactions are key to their effective use in environmental remediation. This review critically evaluates the diverse synthesis methods of GQDs, including bottom-up and top-down approaches, their unique optical, electronic, and chemical properties, and their surface functionalization strategies. We also provide an in-depth assessment of their performance in various water treatment technologies, such as adsorption, membrane filtration, photocatalysis, chemical and electrochemical degradation, and sensing/monitoring, highlighting the mechanisms of pollutant removal and factors influencing the performance. We further discuss how combining GQDs with other materials can enhance treatment efficiency and broaden their practical applications. In addition, we highlight current challenges and propose future research directions to enhance the safe, scalable, and effective use of GQDs for advanced water treatment applications, including integration with other materials and real wastewater systems.