SO2 adsorption and its direct proportional dissociation on the Cu(100), Cu(110), and Cu(111) surfaces: a periodic DFT study

There are some experimental data on the dissociation temperature of SO2 on different Cu surfaces, but the structural information of the transition state is limited to Cu(100), 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(100), Cu(110), and Cu(111). Data show that the most exothermic adsorption process of SO2 occurs on the Cu(110) due to its more open surface compared to the other copper surfaces. In contrast, SO2 is more readily dissociated to SO + O and S + 2O on the Cu(111) surface, owing of the higher coordination number of Cu atoms on this surface. The first-step barrier energy for the dissociation of SO2 to SO + O is +0.93 eV on this surface, while the second-step barrier energy for the dissociation of SO to S + O is +0.74 eV. For SO2 dissociation on Cu(110), the energies for both steps are endothermic (+0.3 and +0.17 eV, respectively), and the backward barrier energies for the two steps are lower than their forward barrier energies (+0.73 eV compared to +1.03 eV, and +0.94 eV compared to +1.11 eV). The location of the transition state (TS) indicates that the structure of the TS for SO2 dissociation on the Cu(100) and Cu(111) surfaces more closely resembles the products, while the TS structure for SO on all Cu surfaces is more similar to the reactants.

SO2 adsorption and its direct proportional dissociation on the Cu(100), Cu(110), and Cu(111) surfaces: a periodic DFT study Keywords:

SO2 adsorption , direct SO2 reduction , Cu(100) , Cu(110) , Cu(111)