Composites of carbon quantum dots (CQDs) are important materials to utilize the optical properties of CQDs in diverse applications including photoluminescence-based sensing and LED phosphors. Combining pre-prepared CQDs with a polymeric matrix usually causes changes in the optical properties of CQDs due to unavoidable aggregation. Recently, the preparation of composites based on in-situ formed CQDs has been debated to overcome the aggregation limits of the conventional mixing methods. Herein, we have demonstrated the synthesis of homogeneous CQDs composites by simple thermal annealing blends of aluminum hydroxide (AlOH), citric acid (CA), and urea (URA). Transmission electron microscopy (TEM), X-ray diffraction, and Raman spectroscopy studies revealed the formation of individual CQDs with a diameter of about 2–9 nm dispersed homogeneously over the AlOH matrix. The composites have a broad excitation band centered at about 360 nm and exhibit excitation-dependent photoluminescence which was similar to that of hydrothermally synthesized CQDs from CA and URA. The photoluminescent intensity of the composite was stable to UV irradiation and responded selectively to Cu(II) ion demonstrating its potential application in Cu(II) sensing.

One-pot synthesis of homogeneous carbon quantum dotsaluminum hydroxide composite and its application in Cu(II) detection
    Abstract
    1 Introduction
    2 Experiment
    3 Results and discussion
    4 Conclusion
    Acknowledgements 
    References

• Xuan‑Dung Mai(Department of Chemistry, Hanoi Pedagogical University 2 (HPU2), 32 Nguyen Van Linh, Vinh Phuc, Vietnam) Corresponding author
• Thi‑Thu Bui(Department of Chemistry, Hanoi Pedagogical University 2 (HPU2), 32 Nguyen Van Linh, Vinh Phuc, Vietnam, Thi Cau Secondary School, Block 2 Tran Ba Linh, Bac Ninh, Vietnam)
• Dai‑Luat Tran(Department of Chemistry, Hanoi Pedagogical University 2 (HPU2), 32 Nguyen Van Linh, Vinh Phuc, Vietnam)
• Van‑Tuan Mai(Department of Natural Sciences, Electric Power University, Hanoi, Vietnam)
• Ngoc‑Huyen Duong(School of Engineering Physics, HUST, Hanoi, Vietnam)
• Van‑Hao Nguyen(Institute of Science and Technology, TNU-University of Sciences, Tan Thinh, Thai Nguyen, Vietnam)