Color change mechanism and application of oxidized carbon dots/I2O4 composite (OCDs/I2O4) in alcoholic beverages

Currently, ethanol detection in alcoholic beverages typically relies on complicated and costly approaches, including gas chromatography, liquid chromatography, and mass spectrometry, etc. Herein, we developed a non-toxicity, practical, low-cost and portable visual indicator for ethanol detection based on OCDs/I₂O₄ nanopowders. By color change, the OCDs/I₂O₄ can visually indicate ethanol concentration ranging from 14 % vol to 56 % vol and the detection limit can be further extended to 2 % vol with a UV-visible spectrum. The OCDs/I₂O₄ indicator shows good stability and long-term endurance for at least 18 months, and it can be used under different temperatures (at least from 3 °C to 40 °C) and humidity (at least from 10 % to 90 %). A possible mechanism for the color change has been proposed based on the covalent-link hydrogen bonding change between OCDs and I₂O₄. The proposed OCDs/I₂O₄ composite offers a convenient and practical solution for ethanol monitoring in various alcoholic beverages.