Photocatalytic performance of Y2Ti2O5S2 prepared via carbon disulfide sulfurization

Abstract

Y2Ti2O5S2 (YTOS) has a narrow bandgap and exhibits excellent stability, and so it is a potential high-performance oxysulfide photocatalyst for solar-driven water splitting to produce green hydrogen. However, YTOS is typically synthesized in sealed quartz tubes, often in the presence of flux reagents, and such processes are difficult to scale up for practical applications. Alternatively, YTOS can be synthesized using a stream of gaseous H2S as a sulfurizing reagent but the reaction requires a high temperature and the resulting material suffers from a high density of defects and impurities. The present work demonstrates the synthesis of YTOS using carbon disulfide (CS2) as a sulfurizing reagent in the presence of a flux. Owing to the high activity of CS2 and the enhanced mass transfer provided by the flux, YTOS could be formed from oxide precursors at a lower temperature than that employed when using H2S. The photocatalytic H2 evolution activity of the resulting YTOS was greater than that of YTOS synthesized using the conventional solid-state reaction or H2S sulfurization methods and comparable to that of YTOS prepared by the flux-assisted method. CS2 sulfurization represents a new approach for the synthesis of functional oxysulfide photocatalysts in a manner that may be suitable for mass production.