6533b82efe1ef96bd12943ee

RESEARCH PRODUCT

Water splitting through model surfaces of metal oxides : ferroelectric polarization towards water adsorption processes

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The properties of out-of-plane polarized BaTiO3(001) thin films were investigated from first-principles calculations and photoemission spectroscopy. Firstly, density functional theory calculations (DFT) were used to unravel the nature of the Pt(001)/BaTiO3(001) interface. In particular, the influence of the substrate on the ferroelectric properties of the BaTiO3 overlayer has been studied. Among the results, it can be pointed that platinum tends to increase the ferroelectric domain size of BaTiO3.Then, the adsorption of water on BaTiO3 was described by means of DFT calculations. The impact of the polarization as well as the influence of the nature of the surface termination on water adsorption were studied. Different adsorption processes depending on the chemical nature of the surface termination were evidenced. Additionally, water was shown to switch the polarization towards the upward direction on the TiO2 termination while the downward polarization is stabilized in the BaO termination.Finally, time-resolved photoemission spectroscopy was used to measure the charge dynamics of photogenerated electron-hole pairs in both BaTiO3 and Fe2O3. Near ambient pressure conditions allowed to record the charge dynamics in hematite while exposed to water, revealing a significant modification of the band bending induced by water adsorption.