Turn-Off Fluorescence Sensor for the Detection of Ferric Ion in Water Using Green Synthesized Wrightia coccinea Carbon Quantum Dot

The current study report that the production of carbon quantum dots from Wrightia coccinea (WC) leaves using an eco-friendly, one-pot process. The structural, morphological, and optical characteristics of the CDs made from W. coccinea leaves by hydrothermal treatment at 200 °C for six hours were assessed using a variety of spectroscopic and electron microscopy techniques. The average size of CD was found to be approximately 5 nm using transmission electron microscopy (TEM) and the quantum yield of the produced CD was 15.6%. The synthesized CDs demonstrated extraordinary sensing capacity with a detection limit of 0.511 µM for ferric ion detection. The impact of varying pH levels on the fluorescence behavior of CD was thoroughly investigated. The maximum fluorescence intensity was examined at pH 3. Therefore, to detect Fe³⁺ ions as best as possible, the pH of the entire solution was adjusted to a value of 3. Furthermore, the pH-dependent fluorescence feature of CDs can be exploited by pH-sensitive fluorescence sensors. In the future, this might provide an added advantage for pH-based fluorescence sensor applications.