Strontium Titanium Oxysulfide (STO-S) and its Photoelectrochemical properties

Photoelectrochemical property of oxysulfide is of great interest for water splitting and hydrogen production applications due to its tunability of bandgap from ultraviolet to visible-light region and high reactivity for redox reaction [1,2]. Understanding the interaction between oxysulfide surface and water is essential to enhance photoelectrochemical performance. However, fundamental understanding during catalytic reactions at the interface have not been remained in its infancy yet. Ambient pressure X-ray photoemission spectroscopy (AP-XPS) is useful to investigate chemical bonding characteristics of the solid surfaces exposed with various gas environments, such as water (H₂O), up to a few millibar pressure [3]. Here, we examined surface bonding characteristics of both SrTiO3 (STO) and sulfur-doped SrTiO3 (STO-S) in H₂O gas environment using the AP-XPS. We revealed that surface oxygen states (O^2-) is a dominant constituent at STO-S surface when H₂O gas is adsorbed on the surface. Our results suggest that the active surface states are largely enhanced in the STO-S compared to the STO and propose potential application of STO-S for the photocatalytic applications.

[1] Nano Energy. 22 (2016) 129, [2] Nat. Mater. 18 (2019) 827, [3] Phys. Chem. Chem. Phys. 21 (2019) 4920