Recent advances in the synthesis and applications of aquatic ecosystems biomass-derived carbon quantum dots: A review

Carbon quantum dots (CQDs) as a zero-dimensional nanomaterial are receiving enormous scientific attention owing to intriguing physicochemical features. Consequently, CQDs have been researched for various applications. In this context, preparation of CQDs using green synthesis methods presents numerous benefits over the conventional chemical routes. From this perspective, this review article explores the application of nature-abandoned biomasses to produce CQDs that grow in aquatic ecosystems and belong to different categories, including aquatic weeds, aquatic plants, algae, and residual biomasses of different organisms. We comprehensively summarize different strategies to synthesize CQDs and evaluate their features, particularly size and optical properties. Furthermore, based on the reported research studies, we discussed the applications of CQDs as promising carbon-based nanomaterials, such as for developing sensing probes to detect heavy metal ions and chemical compounds, photocatalysts to degrade or remove pollutants, bioimaging probes, invisible ink, agents for UV-blocking film, etc. This review may provide valuable insights into green route-derived CQDs utilizing residual biomass of aquatic ecosystems for various applications. Finally, future opportunities and key challenges have been discussed in this direction.