Dual Functional Si, N-Codoped Carbon Quantum Dots for Selective Fluorescence Sensing of Fe3+ and Visible-Light Photocatalysis of Organic Dyes

This work reports a simple, low cost and eco-friendly one-step hydrothermal method to obtain Si- and N-doped carbon quantum dots (Si-N-CQDs) using only citric acid and (3-aminopropyl) trimethoxysilane. These codoped Si-N-CQDs demonstrated 0D spherical morphology and an average size of ∼ 2.54 nm as well as good solubility in water and high quantum yield equal to 14.3%. Fluorescence emission of these Si-N-CQDs was quenched selectively under the presence of Fe 3 + . Based on this property, we developed a very sensitive sensor capable of detecting Fe 3 + up to 400 μ M concentration with a 3.14 μ M detection limit. This sensor was used for Fe 3 + detection in real tap and lake water and demonstrated satisfactory recovery equal to 102.3–108.0% and 103.5–108.5%, respectively. Photocatalytic activity of our Si-N-CQDs was demonstrated using methylene blue (MB) organic dye. The degradation rate of MB under visible light irradiation increased 2.7 times under the presence of Si-N-CQDs within 60 min. Such excellent performance was attributed to very efficient light absorption of Si-N-CQDs as well as excellent electron transfer and separation of photogenerated charge carriers.