Comparing Interaction Energies of Water and NH\u3csub\u3e2\u3c/sub\u3e Adsorbate Across Varying Coverages

Catalysts are used in many industrial processes to make essential chemical reactions feasible. Therefore, it is important to understand the details of how catalysts promote reactions, particularly in the aqueous phase, where water is involved. In this investigation, the coverage of the adsorbate was changed, where the adsorbate was the group of molecules interacting with the catalyst, in order to determine how the energy of interaction between the water and adsorbate changes. Five unit cells were constructed, which included an 18x18x3 Pt catalyst surface, an adsorbate layer directly above the catalyst, and a randomly generated H2O layer. The five coverages of adsorbate used were 1/324 ML, 1/36 ML, 1/4 ML, 1/2 ML, and 1 ML. Two molecular dynamics simulations were run using the LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) Molecular Dynamics Simulator. First, frames were generated to simulate the movement of water. Then, the interaction energy between the adsorbate and water for each frame was calculated. This energy was then averaged to find the interaction energy for each unit cell, and the interaction energy per NH2 molecule was also calculated. As expected the energy became more negative with an increase in the number of NH2 molecules. For the energy per NH2 molecule, there was a minimum at the 1/4 ML cell. However, more coverages should also be explored to better support these results and ensure that there is a real correlation