The Effect of Excess Electron and hole on CO(2) Adsorption and Activation on Rutile (110) surface

CO(2) capture and conversion into useful chemical fuel attracts great attention from many different fields. In the reduction process, excess electron is of key importance as it participates in the reaction, thus it is essential to know whether the excess electrons or holes affect the CO(2) conversion. Here, the first-principles calculations were carried out to explore the role of excess electron on adsorption and activation of CO(2) on rutile (110) surface. The calculated results demonstrate that CO(2) can be activated as CO(2) anions or CO(2) cation when the system contains excess electrons and holes. The electronic structure of the activated CO(2) is greatly changed, and the lowest unoccupied molecular orbital of CO(2) can be even lower than the conduction band minimum of TiO(2), which greatly facilities the CO(2) reduction. Meanwhile, the dissociation process of CO(2) undergoes an activated CO(2)(−) anion in bend configuration rather than the linear, while the long crossing distance of proton transfer greatly hinders the photocatalytic reduction of CO(2) on the rutile (110) surface. These results show the importance of the excess electrons on the CO(2) reduction process.