Surface Reconstruction Promotes CO<sub>2</sub> Activation on the SrTiO<sub>3</sub>(001) Surface: Insight from Quantum Dynamics
Xiaodan Yan, Jinlu He, Run Long
Abstract
Photocatalytic reduction of CO 2 into high-value-added chemicals represents a promising pathway for energy production. However, the efficiency of this process remains constrained by the poor performance of current photocatalysts. A fundamental challenge stems from the high energy level of the lowest unoccupied molecular orbital (LUMO) of CO 2 relative to the conduction band minimum (CBM) of most semiconductor photocatalysts, which hinders effective electron transfer and activation. In this study, we systematically investigate the role of surface reconstruction in CO 2 activation on the SrTiO 3 (STO) (001) surface through an integrated time-dependent density functional theory, the impulsive two-state model, and nonadiabatic molecular dynamics simulations. Our results show that the formation of the CO 2 – anion radical is accompanied by excitation of bending and antisymmetric stretching vibrational modes, in contrast to the symmetric stretching observed in neutral CO 2 . On the pristine STO surface, the CO 2 LUMO fluctuates within the conduction band and fails to induce C═O bond cleavage. Remarkably, surface reconstruction lowers the energy of the CO 2 LUMO below the STO CBM, enabling efficient trapping to form the CO 2 – anion radical. When the excitation lifetime (τ) is 15 fs, the CO 2 LUMO remains below the CBM for over 200 fs, facilitating prolonged electron capture. Increasing τ to 20 fs leads to progressive weakening of the C═O bonds and ultimately results in molecular dissociation and CO formation within 20–30 fs. These findings uncover the critical role of surface reconstruction in tuning the electronic structure and promoting CO 2 activation, offering valuable mechanistic insights to guide the rational design of next-generation photocatalysts for efficient CO 2 reduction.