SO۲ adsorption and its direct proportional dissociation on the Cu(۱۰۰), Cu(۱۱۰), and Cu(۱۱۱) surfaces: a periodic DFT study

There are some experimental data on the dissociation temperature of SO۲ on different Cu surfaces, but the structural information of the transition state is limited to Cu(۱۰۰), and for other surfaces only adsorption data in molecular form are available. In this work, we will systematically investigate all three copper surface orientations of Cu(۱۰۰), Cu(۱۱۰), and Cu(۱۱۱). Data show that the most exothermic adsorption process of SO۲ occurs on the Cu(۱۱۰) due to its more open surface compared to the other copper surfaces. In contrast, SO۲ is more readily dissociated to SO + O and S + ۲O on the Cu(۱۱۱) surface, owing of the higher coordination number of Cu atoms on this surface. The first-step barrier energy for the dissociation of SO۲ to SO + O is +۰.۹۳ eV on this surface, while the second-step barrier energy for the dissociation of SO to S + O is +۰.۷۴ eV. For SO۲ dissociation on Cu(۱۱۰), the energies for both steps are endothermic (+۰.۳ and +۰.۱۷ eV, respectively), and the backward barrier energies for the two steps are lower than their forward barrier energies (+۰.۷۳ eV compared to +۱.۰۳ eV, and +۰.۹۴ eV compared to +۱.۱۱ eV). The location of the transition state (TS) indicates that the structure of the TS for SO۲ dissociation on the Cu(۱۰۰) and Cu(۱۱۱) surfaces more closely resembles the products, while the TS structure for SO on all Cu surfaces is more similar to the reactants.

کلیدواژه ها:

SO۲ adsorption ، direct SO۲ reduction ، Cu(۱۰۰) ، Cu(۱۱۰) ، Cu(۱۱۱)