Rational designed strategy to dispel mutual interference of mercuric and ferric ions towards robust, pH-stable fluorescent carbon nanodots.

As one of the most promising fluorometric nanosensors for metal ion sensing, carbon nanodots (C-dots) have developed rapidly in recent years. However, it is still a thorny problem to shield the mutual interference of two metal ions towards C-dots, e.g., Hg2+ and Fe3+ ions. In the present work, we propose rational routes for the unique interaction between C-dots and Hg2+ or Fe3+. The selectivity of the as-obtained label-free C-dots can be effectively switched by P3O105- and SCN-. The resultant C-dots possess superior photoluminescence intensity stability in a wide pH range or in certain redox circumstances, which are highly preferred in terms of practical metal-ion detection. Moreover, the quenching-recovery-regeneration performances and quenching mechanisms were also investigated. Based on this stable and recoverable sensing platform, this in-depth study for dispelling interference from Hg2+ and Fe3+ ions may open up a new paradigm for developing potential detection of multi-metal ions using C-dots with switchable selectivity.