Single-step synthesis of polychromatic carbon quantum dots for macroscopic detection of Hg²

Two kinds of carbon quantum dots (CQDs), having luminous peaks at 480 and 525 nm, were obtained by a single-step hydrothermal method. The detection of Hg²⁺ by two kinds of carbon dots was further explored. In order to compensate for the weak luminescence of blue carbon dots (480 nm) and low sensitivity of green carbon dots (525 nm), mixed carbon dots were examined for Hg²⁺ detection. The mixed carbon dots showed a better detection of Hg²⁺ ions. Low detection limit of 0.05 μM was found to be in the range of 0-1.0 μM of Hg²⁺. Moreover, in this range, the change of fluorescence intensity can be clearly seen under the ultraviolet lamp, which will be conducive for the practical application of detecting mercury ions with carbon dots.