Synthesis of Y 2 Ti 2 O 5 S 2 by thermal sulfidation for photocatalytic water oxidation and reduction under visible light irradiation

Y2Ti2O5S2 has an absorption edge wavelength of 640 nm and functions as a photocatalyst for overall water splitting under visible light. At present, this material is synthesized using a solid-state reaction that requires several days and generates particles tens of micrometers in size. The present work demonstrates an alternative synthesis method based on thermal sulfidation under a H2S flow to obtain smaller particles. Using this new process, a precursor mixture was converted into Y2Ti2O5S2 after several hours of heating at 1423 K, although the resulting material contained some Y2O2S and TiSx as impurities. The primary Y2Ti2O5S2 particles were plate-like and some exposed (001) facets as the basal plane, while the majority aggregated to form secondary particles 1–2 µm in size. After loading with Rh, or with either IrO2 or CoOx, this material was active during sacrificial photocatalytic H2 and O2 evolution reactions, respectively.