The TiO2-Pt-water interface is of great relevance in photocatalysis where Pt is widely used as a co-catalyst for enhancing hydrogen evolution in aqueous TiO2. Using ab initio molecular dynamics, we investigated this interface focusing on Pt single atoms supported on anatase TiO2(101) in a water environment. Based on recent experiments showing a broad distribution of Pt coordination sites in TiO2, we examined six distinct single-Pt supported species with different nominal Pt oxidation states, namely: Pt, PtOH, and PtO2 species adsorbed on the stoichiometric surface; Pt adsorbed at a surface oxygen vacancy (Ov); and Pt substituting a surface Ti cation (PtTi), both without and with an accompanying Ov (PtTi + Ov). As found for the pristine anatase surface, interfacial water remained intact in the presence of a nearly neutral Pt adatom within the time duration of our simulations (∼15 ps). Similarly, no (or only temporary) water dissociation was observed at the PtTi + Ov and PtO2 interfaces, due to the formation of very stable planar Pt coordination structures that interact only weakly with water. In contrast, water dissociated with OH- (H+) on the Pt atom when this substituted a surface Ti (oxygen) ion as well as on PtOH.
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy
- Physical and Theoretical Chemistry