Adsorption-improved MoSe₂ nanosheet by heteroatom doping and its application for simultaneous detection and removal...

Water pollution arising from heavy metal ions continues to be a major environmental problem, which represents a serious threat to human beings and animals worldwide. New materials that can simultaneously detect and remove these toxic ions are urgently required. Herein, nitrogen and sulfur co-doped molybdenum selenide nanosheets (N, S-MoSe₂) were prepared and found to be fluorescently responsive to mercury (II) with an improved adsorption capacity (208.33 mg g^-1), thereby providing the possibility for the simultaneous detection and removal of mercury (II) in water samples. The great affinity was the result of the complexation of mercury (II) with Se and S atoms in N, S-MoSe₂ as well as the electrostatic adsorption of cation mercury (II) on negatively charged N, S-MoSe₂. Besides good sensitivity and selectivity toward mercury (II), N, S-MoSe₂ displayed a relatively consistent performance under a wide pH range from 3 to 10. The removal efficiency reached 87.5% with fast adsorption kinetics, and N, S-MoSe₂ could be reused after simple treatment. Thus, this work is expected to provide new material for the detection and removal of mercury (II) in an aqueous solution and offer an insight into the interaction between heavy metal ions and inorganic nanomaterials.