Development of Highly Efficient Dual Sensor Based on Carbon Dots for Direct Estimation of Iron and Fluoride Ions in Drinking Water

The fluorescent nanomaterial carbon dots (CDs) have attracted tremendous attention in the recent times because of their unique physico‐chemical characteristics. Highly fluorescent CDs were prepared through a simple and nontoxic one‐step hydrothermal carbonization of polyvinylpyrrolidone (PVP). The as‐synthesised CDs, without any pre‐treatments or post‐treatments, show high stability over a broad pH range and have an excellent potential in chemical sensing applications. The as‐prepared CDs have been demonstrated to be an excellent nano probe for Fe 3+ ions sensing in aqueous media based on the fluorescence quenching with high sensitivity (lower limit of detection ∼ 1 μM) and selectivity towards Fe 3+ ions. “Turn off” fluorescence arises due to the formation of CDs‐Fe 3+ nanocomposite complex in the solution. The nanocomposite complex forms by the attachment of Fe 3+ ions to the surface emissive site of the CDs, resulting in an obvious fluorescence quenching. Here, CDs itself act as a promising nano carrier for loading of Fe 3+ ions to form the CDs‐Fe 3+ nanocomposite complex in the solution. In addition to all, in this study we are intensely focused to explore the application of CDs‐Fe 3+ nanocomposite complex. We have used the CDs‐Fe 3+ nanocomposite complex as a novel sensor probe for the detection of F ‐ ions in aqueous media based on “Turn on” fluorescence mechanism. “Turn on” fluorescence occurs due to the formation of thermodynamically highly stable [FeF 6 ] 3‐ complex and bare CDs in the solution. The developed sensor has high sensitivity (lower limit of detection ∼ 1 μM) and selectivity towards F ‐ ions over a wide‐ranging other competing anions. Finally, we successfully demonstrate the real life application of the developed sensor by estimating the trace F ‐ ions in the real world drinking water samples.