The effect of solvent polarity on emission properties of carbon dots and their uses in colorimetric sensors for water and humidity

Carbon dots have emerged as promising nanomaterials because of their outstanding properties. The issue is to obtain multicolor emissions of carbon dots. Carbon dots from aliphatic acids and aromatic amines have successfully been synthesized, and their emission properties are controlled easily by solvents. This study helps deepen our understanding of the solvent-dependent behavior of nitrogen-doped carbon dots, especially their solvent polarity effects. The physical, chemical, and optical properties of carbon dots were analyzed, and the possibility of their use for detecting water in organic solvents and as paper-based humidity sensors was demonstrated.