Adsorption energy is defined as the decreasing energy when two materials are combined under the adsorption process in which an atom, ion, or molecule (adsorbate) is attached to the surface of a solid (adsorbent). Adsorption energy is obtained by calculating the difference between the energy of the adsorption model and the sum of the energy which separately calculated for each structure composing the adsorption structure. Adsorption energy, Ea, can be calculated as follows:
Therefore, in order to obtain the adsorption energy, scientists usually calculate the energies for the following three models: Slab supercell structure which is also called adsorbent, adsorption system which is the slab structure with the adsorbent, and adsorbate in the vacuum.
Application of Adsorption Energy Calculation
- Study the chemical engineering properties
- Explore the adsorption mechanism
- Determine the energetic heterogeneity of the surface of a solid
Figure 1. DFT calculations to investigate the catalytic performances of Niphosphide. (a) Optimized surface structures. (b) Free energy profiles. (Loco, D.; et al. 2015)
Our Adsorption Energy Calculation Workflow
At Alfa Chemistry, we have developed a mature workflow for calculating the adsorption energy of gas molecules on metal surfaces. Our reliable adsorption energy calculation process is as follows:
- Optimize the crystal structure of metals
- Establish and optimize the gas molecular structure model
- Build a metal surface structure model
- Relax the metal surface
- Optimize the metal surface and calculate the density of states of the system
- Add gas molecules structure on the metal surface and optimize the structure
- Energy analysis
- Density of states (DOS) analysis