Graphene based water pollutant sensor for detection of carcinogenic heavy metals: DFT investigation

The present article discusses sensing of carcinogenic heavy metals (Arsenic (As), Cadmium (Cd), Chromium (Cr), Mercury (Hg) and Lead (Pb)) through graphene nanosheet as water pollutant sensor. Density functional theory based first principle calculations have been performed to understand the sensing behavior through computation of energetic properties and Mulliken population. Our investigation revealed that graphene has no sensitivity towards water molecule, but interacts strongly with the carcinogenic heavy metals with significant charge transfer. As and Cr show chemisorption over the graphene sheet, while Pb show strong physisorption with smaller binding distance. To further understand the sensing ability, the variation in the conductivity and density of states (DOS) profile of graphene has been investigated in the presence of these heavy metals. Our results indicate the great potential of graphene nanosheets for detection of As and Pb in water. (author)