Comprehensive study of interaction between graphene and toxic heavy metals (Cd, Hg , Pb)
||Comprehensive study of interaction between graphene and toxic heavy metals (Cd, Hg , Pb)|
||Ivan Shtepliuk <email@example.com>|
||2017-12-01 – 2020-12-01|
WHY: Due to ever-increasing industrial activities, agriculture and urban waste waters, toxic heavy metals such as mercury, cadmium and lead are released in the sea water and environment. These substances can cause detrimental effects on the ecosystem and human health. Therefore, the pollution induced by hazardous heavy metals exceeding maximum allowable levels is a great challenge for global sustainability. In this respect, it is vitally important to propose and comprehensively investigate sensing platform using ecofriendly material, which has high chemical activity and tunable intrinsic electronic properties intrinsic electrical properties.
One of the most advanced candidates for such sensors is graphene, which in principle should ideally meets the aforementioned requirements.
WHAT: An overall goal of this project is to understand the physics underlying the interaction between heavy metals (Cd, Hg and Pb) and graphene in vacuum and in solvents (water, acetic acid etc.).
HOW: The main idea of the proposed work is that interaction of heavy metals with graphene has to change its intrinsic electronic properties (Fermi level position, carrier density and band gap energy). Such a change should be reflected on the electrical properties of the graphene-based devices (electrodes, diodes, FET), which can be used as sensing platform. Comprehensive theoretical study will help to create the graphene-based sensors including attaining the optimal growth parameters of graphene layers and deep understanding the mechanisms of the recognition of the heavy metals. The work I propose will provide the physical insight into mechanisms, particularly the extent to which the properties of graphene-based sensors can be modified by controlling the surface chemistry through thickness and doping effects.
WHERE: The project complements and expands the research field in the Semiconductor Materials division at Linköping University (LiU).
At the first stage of DFT calculations, it is necessary to consider the adsorption of Cd, Hg and Pb at different high-symmetry positions on the graphene surface, such as on-top site, hollow site and bridge site in order to establish the most favorable (from the energetic and thermodynamic point of view) geometrical configuration of incoming adsorbates. For simulation of graphene, I will plan to use both large graphene clusters with edges terminated by hydrogen atoms (coronene, circumcoronene and circumcircumcoronene) and infinite graphene sheet (Periodic Boundary Conditions, PBC calculations). To study the solvent effect (water, acetic acid), I will plan to use Polarizable continuum model (PCM). It should be pointed out that the geometry optimization of interacting systems (graphene supercell–heavy metals) will be performed at the Becke3LYP level of density functional theory with a 6-31G basis set on carbon and a basis set of Stuttgart-Dresden SDD effective core potentials on Cd, Hg and Pb atoms. DFT calculations of graphene clusters and geometry optimization will be performed using the default convergence criteria in the Gaussian09 package.