Green functionalized carbon dots for photocatalytic dye degradation: A functional review

Abstract

The rising pollution of water resources with synthetic dyes creates serious environmental and health risks. Conventional dye removal techniques, such as physical, chemical, and biological processes, are frequently limited by high operational costs, partial degradation, and the formation of secondary pollutants. Recent advances in nanotechnology have led to the development of green carbon dots (GCDs) as effective, environmentally friendly photocatalysts for dye degradation. This review provides a detailed summary of GCD production, methodologies, structural and optical features, along with its application as a catalyst for dye removal under light irradiation. Furthermore, a rigorous comparison is made between traditional dye-removal methods and photocatalytic systems using GCDs, emphasizing their higher degradation efficiency, sustainability, and cost-effectiveness. The study concludes with future directions for improving photocatalytic performance through heteroatom doping, surface modification, and hybrid composites to enhance sustainable water treatment technologies. In addition to reviewing the synthesis and photocatalytic activity of GCDs, this study emphasizes their practical application in industrial-scale wastewater treatment systems, particularly in the textile and printing industries. The current study is unique in that it focuses solely on green-precursor-based carbon dots and their mechanism-driven function in dye degradation, a topic that has not been thoroughly studied. A qualitative comparison with established physicochemical and biological approaches reveals that GCDs exhibit higher degradation efficiency (>90 %), improved photostability and recyclability, and lower operational costs. This analysis expands on the economic significance and future promise of GCDs as sustainable photocatalysts for real-world environmental remediation.