Dual-functional platform based on 315-nm Stokes shift Al, N-doped carbon dots for Hg²⁺ onsite detection and removal

Al, N-doped carbon dots (Al-NCDs) with a 315-nm Stokes shift and 31.4% quantum yield were designed to mitigate autofluorescence interference in complex matrices. DFT calculations coupled with structural studies revealed an Al-pyridinic-N coordination modulated electronic transitions, enabling the unique optical properties. Al-NCDs exhibited high sensitivity and selectivity toward Hg²⁺, enabling a dual-functional Hg²⁺ control platform integrating rapid detection and removal. The rapid detection achieved a 0.030 ~ 4.0 μmol·L^-1 linear range and 8.0 nmol·L^-1 detection limit which was applied to agro-samples and river water with recoveries of 90.0 ~ 116.3%. Moreover, smartphone-based on-site detection (LOD: 0.2 μmol·L^-1, 30 samples/10 min) further extends practicality. Crucially, Al-NCDs-embedded nanohydrogels exhibit rapid Hg²⁺ removal with capacity of 287.2 mg·g^-1, completing the "detection-remediation" control chain. This dual-functional platform bridges large Stokes-shift sensoring with food safety interventions, providing a prototype for Hg control in complex systems.