File Name : figure s1.tif

Caption :  graphs of xps for ti<sub>3</sub>c<sub>2</sub> qds. (a) fully scanned spectra (b) c 1s spectrum of ti<sub>3</sub>c<sub>2</sub> qds. (c) ti 2p (d) o 1s spectrum of ti<sub>3</sub>c<sub>2</sub> qds.

File Name : figure s2.tif

Caption : the fl intensity of ti<sub>3</sub>c<sub>2</sub> qds changes with (a) temperature, (b) time (under 365 nm ultraviolet light), (c) ph and (d) time (stored in a refrigerator at 4 ℃).

File Name : figure s3.tif

Caption : (a)the effect of different concentrations of co<sup>2+</sup> on the fluorescence of ti<sub>3</sub>c<sub>2</sub> qds. (b) linear relationships between the fluorescence of ti<sub>3</sub>c<sub>2</sub> qds and the concentration of co<sup>2+</sup>