Table 2. Reaction Energies and Single-Step Energies (in eV) for the Dissociation to CO + O, Hydrogenation to COOH, and Hydrogenation to HCOOa.
| CO + O |
COOH |
HCOO |
||||
|---|---|---|---|---|---|---|
| Er | Es | Er | Es | Er | Es | |
| TiC | ||||||
| (001) | –1.13 | –0.23 | –1.25 | 0.59 | 0.19 | 2.03 |
| (011) | –7.05 | –3.6 | –3.38 | 1.43 | –3.38 | 1.43 |
| (111) | –5.70 | –2.60 | –2.76 | 1.43 | –3.84 | 0.35 |
| ZrC | ||||||
| (001) | –1.72 | –0.04 | –1.70 | 0.95 | –1.02 | 1.63 |
| (011) | –5.03 | –0.84 | –3.73 | 1.71 | –5.92* | –0.48* |
| (111) | –5.67 | –2.49 | –2.47 | 1.91 | –3.9 | 0.48 |
a
For each reaction, two energies are reported, differing for the reference used: in the column on the left of each section, the reaction energy Er is reported, which is the energy of the intermediate on the surface of the catalyst minus the energy of the gas-phase reactants and pristine surface; in the column on the right of each section, the single-step energy Es is reported, which is the energy of the intermediate on the surface of the catalyst minus the energy of the previous intermediate on the same surface. The energies reported for HCOO on ZrC(011) are marked with an asterisk because they are referred to the formation of HCO + O since HCOO dissociation occurs spontaneously on this surface.