Adsorption and decomposition of H2S on the Ni(1 1 1) and Ni(2 1 1) surfaces: A first-principles density functional study

The adsorption and dissociation of H₂S on Ni(1 1 1) and Ni(2 1 1) were both studied using first-principles density functional calculations (DFT-GGA) and periodic supercells. In this study, the adsorption configurations and structural parameters of H₂S, HS, S and H have been given on Ni(1 1 1) and Ni(2 1 1). And the co-adsorption behaviors of HS + H and S + H were also investigated. The orders of the adsorption energy for these substances on Ni(1 1 1) and Ni(2 1 1) are both as follows: H₂S, H, HS, S. In addition, it is found that the dissociation of H₂S on the Ni metal surface would occur easily through the study of the dissociation mechanism of H₂S. It is worth noting that the difference in energy variation of the first HS fracture of H₂S (H₂S → H + HS) is small on Ni(1 1 1) and Ni(2 1 1)(−1.04 eV and −1.12 eV). However, the energy barrier of the dissociation of the second HS(HS → H + S) on Ni(2 1 1) surface is greater than that of Ni(1 1 1), which was explained in structure, mulliken charge and PDOS. These results provide more information for further understanding the mechanism of sulfur poisoning on Ni catalyst.