Solid phase synthesis of nitrogen and phosphor co-doped carbon quantum dots for sensing Fe^sup 3+^ and the enhanced photocatalytic degradation of dyes

A facile and one-step strategy has been developed for the preparation of highly fluorescent nitrogen and phosphor co-doped carbon quantum dots (NP-CQDs) through the thermal treatment of the mixture of citric acid and O-phosphorylethanolamine. The as-prepared NP-CQDs emit strong blue-green light under irradiation of 365 nm light and show emission maxima at 475 nm in aqueous solution. And these NP-CQDs exhibit great stability in high-salt conditions, excellent photostability and a high quantum yield of about 8.45%. Interestingly, the NP-CQDs have been successfully utilized for the sensitive and selective fluorometric detection of Fe3+ without interference from other ions in aqueous solution. Moreover, we have found that the NP-CQDs can enhance the photocatalytic activity of TiO2 for the degradation of dyes under simulated sunlight irradiation.