Dual-emission carbon dots-copper nanoclusters ratiometric photoluminescent nano-composites for highly sensitive and selective detection of Hg2+

A novel dual-emission photoluminescent (PL) nano-materials of carbon dots-copper nanoclusters (CDs-CuNCs) nano-composites is prepared for excellent sensitivity and selectivity toward Hg2+. The nano-composites are composed of blue photoluminescent CDs and red photoluminescent CuNCs with similar excitation wavelengths through the electrostatic assembly. The red photoluminescence of CuNCs was inhibited by the nano-composites exposed to Hg2+, while the blue photoluminescence of CDs remained stable. The color of the nano-composites slowly changed from pink to blue with the added of Hg2+ concentration. The limit of detection (LOD) of the nano-composites is 0.31 nmol/L (nM) toward Hg2+ in aqueous solution, when the signal to noise ratio is 3. In addition, a visual PL test paper is prepared. When the Hg2+ solution is added, the color of test paper transforms from pink to blue immediately. Therefore, the nano-composites are very important for efficient and sensitive detection of Hg2+, which show broad application prospects in environmental analysis, food safety detection, biological detection and medical diagnosis in daily life.