- Our society today is heavily dependent on fossil fuels such as coal and oil. However, growing environmental concerns and future fossil fuel supplies have led to interests in alternative fuels. Dimethyl Ether (DME) is an inexpensive, clean-burning, non-toxic, and potentially renewable fuel, making it a suitable choice as an alternative fuel. However, the use of DME in engines or fuel cells is challenged by its reactivity on the catalyst which is not yet fully understood, so more research is needed on DME interactions with the catalyst. In this project, Density Functional Theory (DFT) will be used to look at the interactions between DME and Pt, under a vacuum, both with and without co-adsorbed water. Various configurations and adsorption sites were examined to determine the most stable configurations and the interactions between DME, Pt, and water were studied. Reaction pathways of C-H dissociation for both systems (with and without water) were also studied using Nudge Elastic Band (NEB). Bader analysis was also used to look at electron density of various systems. Overall, it was found that DME had a relatively weak binding energy to the Pt surface of 0.8 eV whereas the DME-water complex had a stronger binding energy of 1.51 eV. It was also found that in a system with DME and a single water molecule, DME preferential binding on a top site to a clean Pt surface, while the water adsorbed on a top site and formed a hydrogen bond with DME. Calculations that simulated the dissociation of a single hydrogen from the DME molecule into a water bilayer resulted in the hydrogen returning back to the DME molecule, suggesting a very low barrier and NEB calculations revealed that hydrogen shuttling does not occur with methyl groups in the presence of a single water molecule.
- Key Words: Dimethyl Ether, DME, Fuel Cell, Density Functional Theory, Pt(111), Solvation Effects, Catalysis