Enhanced-quantum yield sulfur/nitrogen co-doped fluorescent carbon nanodots produced from biomass Enteromorpha prolifera: synthesis, posttreatment, applications and mechanism study

Jingquan Liu,Erkang Wang,Fushuang Niu,Yuanhong Xu,Dan Li,Mengli Liu

doi:10.1038/s41598-017-04754-x

Abstract

Enteromorpha prolifera (E. prolifera), one of the main algae genera for green tide, significantly influences both the coastal ecological environment and seawater quality. How to effectively utilize this waste as reproducible raw resource with credible application mechanism are urgent environmental issues to be solved. Herein, E. prolifera was converted to attractive fluorescent carbon nanodots (CNDs) by one-pot green hydrothermal process. The purity and quantum yields for the as-prepared CNDs can be enhanced upon the post-treatment of ethanol sedimentation. The CNDs can be well dispersed in aqueous medium with uniform spherical morphology, narrow size distribution and average size of 2.75 ± 0.12 nm. The ease synthesis and relatively high quantum yields of the CNDs make E. prolifera inexpensive benefit to the human and nature, such as applications in efficient cell imaging and fiber staining. Furthermore, it was discovered that the fluorescence intensity of the CNDs can be selectively quenched upon Fe3+ addition, which can be used for specific sensitive assay and removal of Fe3+ in aqueous medium. More importantly, it was reasonably proposed that the quenching was resulted from the synergistic effects of CNDs aggregation and Fe3+-CNDs charge-transfer transitions due to the coordination interactions between Fe3+ and the oxygenous groups on the CNDs.

Highlights

Enteromorpha prolifera (E. prolifera), a green macroalgae, has been attracting special and increasing attention recently, especially since 2007 in China’s Yellow Sea
The quantum yields (QYs) for the carbon nanodots (CNDs) prepared before and after the ethanol sedimentation reached 10.1% and 12.3%, respectively, which were higher than most of those obtained from other biomass as carbon sources for CNDs generation
E. prolifera was successfully converted to attractive fluorescent nanostructure CNDs by one-pot green hydrothermal process at 180 °C for 6 h followed by post-treatment of ethanol sedimentation

Summary

Results and Discussion

Conversion of E. prolifera into CNDs and corresponding characterizations. E. prolifera belongs to one renewable biomass possessing advantages of higher production, faster growth rate, availability and low cost. It should be because of the complex components such as crude protein, lipid, and inorganic salts in the biomass E. prolifera This impurity should be one of the reasons for the low QYs (1.2–7.1%) of the CNDs prepared via hydrothermal treatment of varied other biomass such as coriander leaves[15], grass[12], apple juice[11], potato[20], watermelon peel[21], oats[23], etc. The QYs for the CNDs prepared before and after the ethanol sedimentation reached 10.1% and 12.3%, respectively, which were higher than most of those obtained from other biomass as carbon sources for CNDs generation. Biomass Coriander leaves Grass Apple juice Solanum tuberosum Watermelon peel OAts coffee grounds

This work

Conclusions

Additional Information