“Off-on” fluorescence sensor based on phytic acid carbon dots for OH−/H+ detection in metal corrosion

Abstract

Metal corrosion has caused serious waste of resources and materials, and also caused great pollution to the environment. Therefore, it is of great significance to develop a green, fast, and simple method for corrosion sensing. Herein, a phytic acid carbon dots (PA-CDs) based green “off–on” fluorescence sensor was developed for OH− and H+ detection in metal corrosion. The fluorescence of PA-CDs gradually turned off as the concentration of OH− increased from 20 to 340 μmol/L, while its fluorescence was turned on with the addition of 60 ∼ 230 μmol/L of H+ under ultrasonic treatment. This can be utilized for the detection of OH− and H+, with estimated limits of detection at 7.33 μmol/L and 20.34 μmol/L, respectively. The “off-on” behavior of PA-CDs towards the corrosion species OH− and H+ can be attributed to its enhanced aggregation and disaggregation, which are induced by the deprotonation and protonation of the −H2PO4 functional groups. The PA-CDs were loaded onto the film and subsequently employed for Q235 steel packaging. The results revealed that the as-proposed green fluorescence “turn-off” phenomenon can be visually observed after the onset of corrosion on the steel sheet, thereby demonstrating the potential application of PA-CDs film for early-stage corrosion monitoring.