LAUSR

The stability and reactivity of Mo2C and Ni2P surfaces with different terminations are systematically investigated by means of ab initio atomistic thermodynamics and conceptual DFT approaches as a function of the chemical potential (μ). Five surfaces labeled as (001)-Mo-1, (110)-Mo/C, (001)-Ni3P2, (001)-Ni3P2-P, and (001)-Ni3P1 emerge as the most stable ones for Mo2C and Ni2P catalysts depending on μC and μP, respectively. The Fukui function, a reactivity descriptor, reveals that the metal atoms interact preferentially with nucleophilic adsorbates such as H2S. Here, our study predicts that a high concentration of C and P atoms on the surface reduces the catalytic activity where nucleophilic species are involved. The qualitative agreement between the nucleophilic Fukui function (f+) and the adsorption energies indicates that the Ni2P catalyst is, in general, more reactive than Mo2C catalyst. This study may help to improve and optimize the catalytic processes, such as the hydrogenations HDO and HDS, where Mo2C and Ni2P catalysts are involved.