Highly fluorescent N,S,P tri-doped carbon dots for Cl- detection and their assistance of TiO2 as the catalyst in the degradation of methylene blue

The preparation and application exploration of multi-heteroatom doped carbon dots (CDs) have drawn tremendous attention. In this study, the N, S, P tri-doped carbon dots (NSP-CDs) were prepared by one-pot hydrothermal method with sulfonamide and phosphoric acid as precursors, possessing a fluorescence quantum yield up to 33 %. The fluorescence intensity of NSP-CDs exhibited a good linear relationship with the surrounding pH in the range of 3-7, showing the great promising pH sensing potential of NSP-CDs. Moreover, the fluorescence of NSP-CDs could be selectively quenched by Cl-; based on it, a Cl- fluorescence sensor was constructed and successfully applied to detecting Cl(- )in sweat samples with the recoveries of 94 %-110 %. Furthermore, TiO2 was modified with the NSP-CDs by simple immersion method, and the as-prepared composite demonstrated higher photocatalytic activity for the degradation of methylene blue under UV irradiation than pristine TiO2. The prepared NSP-CDs had potential for multiple applications.