Revealing the photocatalytic dissociation of water molecules on rutile TiO surface hybrid functional based linear response time-dependent density functional theory.

Rutile TiO shows great potential for photocatalytic water (HO) splitting into oxygen (O) and hydrogen peroxide (HO). However, the mechanism of surface water oxidation on rutile TiO remains unclear, involving complex ground-state thermal catalysis and excited-state photocatalysis processes. Here, by using linear response time-dependent density functional theory (LR-TDDFT), we investigate HO oxidation at both the ground-state and excited-state levels. Our results show that O formation is thermocatalytic and occurs at room temperature, while HO desorption is driven by photogenerated holes, requiring light to overcome a high-energy barrier, which agrees with experiments showing O formation is more favorable. Furthermore, comparing the computational results obtained using the local PBE and nonlocal HSE functionals, we find the HSE provides a more accurate description of the electronic interactions between TiO and the adsorbates, and the reaction pathways, especially under excited-state conditions. Our work provides a pathway for understanding TiO water oxidation mechanisms.