Synthesis of Carbon Quantum Dots Combined with CuO Nanocubes and Their Application in Metals Ion Detection.

In this study, carbon quantum dots/CuO nanocubes (CQDs/CuO NCBs) nanomaterial has been successfully synthesized using a simple and easy-to-implement method with a quick reaction time (90 min) at 80°C. In particular, carbon quantum dots (CQDs) were obtained by green and environmentally friendly synthesis methods, using abundant and naturally available raw materials from rice flour and applying hydrothermal approach. Besides, cuprous oxide nanocubes (CuO NCBs) were also synthesized through non-toxic compounds. The morphology and composition of CQDs/CuO NCBs and CuO NCBs were analyzed through UV-vis, FTIR, XRD, FE-SEM, TEM, and EDX spectroscopy. The results showed that CuO NCBs have a cubic shape with an average particle size of ~ 29-31 nm, and CQDs have spherical shape with a size of ~ 4-8 nm. In addition, CQDs/CuO NCBs nanomaterial was also employed as a "turn-on" fluorescence sensor" for application in metal ions detection. The obtained results showed that the CQDs/CuO NCBs are potential and promising in detecting Pb ions in the wide range from 1.8 M to 10 M and extremely low limit of detection of 27.8 nM at the excitation wavelength of 340 nm. CQDs/CuO NCBs-based sensors are highly sensitive and selective for Pb detection. Therefore, CQDs/CuO are promising as photocatalytic materials for various applications, including sensors, bio-probes biomedical, optoelectronics, etc.