The Effect of Excess Electron and hole on CO2 Adsorption and Activation on Rutile (110) surface

Abstract

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.

Mechanisms of carbon dioxide reduction on strontium titanate perovskites

“…The photocatalytic conversion of CO 2 takes place in the presence of a photoexcited electron which reduces the SrTiO 3 surface. When the carbonate-like structure described above is adsorbed on the reduced surface, which we have modelled by adsorbing a H atom on SrTiO 3 as in previous works, 22,44 a hydrogen bond between a carbonyl oxygen and the proton on the surface is formed, which is illustrated in Fig. 2a.…”

CO2 and water activation on ceria nanocluster modified TiO2 rutile (110)

“…67,68 The presence of excess electrons and holes was shown to affect adsorption and activation of CO2 at rutile (110), with implications for binding energies, structure and reactivity of adsorbed CO2; both bent CO2anion (excess electrons) and CO2 + cation (excess holes) configurations were identified with energy barriers of 1.12 eV and 0.75 eV respectively. 69 Yang and colleagues showed that subnm Pt clusters at the anatase (101) surface enhanced CO2 activation through provision of additional adsorption sites at the edge of the Pt cluster, reporting increased adsorption strength and, in some instances, the spontaneous formation of a CO2anion due to accumulation of negative charge on the C atom. The authors also reported transfer of electron density from the cluster to the TiO2 substrate which facilitated adsorption at surface sites away from the supported Pt octamer.…”

Ni‐Nanocluster Modified Black TiO2 with Dual Active Sites for Selective Photocatalytic CO2 Reduction

“…Additionally, several theoretical studies have demonstrated that subsurface oxygen vacancy or interstitial defects enhance the bonding of CO 2 adsorption on reduced TiO 2 anatase surfaces . Yang et al illustrated that CO 2 adsorption on reduced anatase TiO 2 was attributable to an electrostatic competition between attractive (Ti−O) and repulsive (Ti−C) interactions according to their density functional theory calculations .…”