The effect of excess electron and hole on CO₂ adsorption and activation on Rutile (110) surface

CO₂ 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 CO₂ conversion. Here, the first-principles calculations were carried out to explore the role of excess electron on adsorption and activation of CO₂ on rutile (110) surface. The calculated results demonstrate that CO₂ can be activated as CO₂ anions or CO₂ cation when the system contains excess electrons and holes. The electronic structure of the activated CO₂ is greatly changed, and the lowest unoccupied molecular orbital of CO₂ can be even lower than the conduction band minimum of TiO₂, which greatly facilities the CO₂ reduction. Meanwhile, the dissociation process of CO₂ undergoes an activated CO₂ - anion in bend configuration rather than the linear, while the long crossing distance of proton transfer greatly hinders the photocatalytic reduction of CO₂ on the rutile (110) surface. These results show the importance of the excess electrons on the CO₂ reduction process.