Fluorescent carbon dots with dual emissions and solvent-dependent properties for water detection in organic solvents

Abstract

Detection of water in organic solvents is of importance in both academic and industrial applications. In this work, we developed dual emissive carbon dots (CDs) through a simple solvothermal method using m-phenylenediamine and phenolphthalein as precursors. The CDs showed excitation-dependent emission properties with both blue and green emissions. In addition, the CDs’ emission peak shifted to longer wavelengths as the polarity of the solvents that dispersed the CDs increased, allowing the CDs to serve as a solvatochromic probe. Besides, the CDs’ emissions could be affected by water in different organic solvents, which have been developed as efficient sensors for the detection of trace amounts of water. The limit of detection (LoD) to water detection in ethanol (EtOH), dimethyl sulfoxide (DMSO), and acetonitrile (MeCN) can be as low as 0.12%, 0.01%, and 0.006%, respectively, utilizing the CDs’ green emissions. By taking advantage of the dual emissions, the ratiometric detection of water has been achieved. The ratiometric signals could be potentially developed as portable naked-eye based sensors for water detection in organic solvents. The obtained CDs could have promising applications to be used in sensing applications considering their easy synthesis, good optical properties and muti-signals for detection.