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Photocatalytic water splitting is an ideal means of producing hydrogen in a sustainable manner, and developing highly efficient photocatalysts is a vital aspect of realizing this process. The photocatalyst Y2Ti2O5S2 (YTOS) is capable of absorbing at wavelengths up to 650 nm and exhibits outstanding thermal and chemical durability compared with other oxysulfides. However, the photocatalytic performance of YTOS synthesized using the conventional solid‐state reaction (SSR) process is limited owing to the large particle sizes and structural defects associated with this synthetic method. Herein, we report the synthesis of YTOS particles by a flux‐assisted technique. The enhanced mass transfer efficiency in the flux significantly reduced the preparation time compared with the SSR method. In addition, the resulting YTOS showed improved photocatalytic H2 and O2 evolution activity when loaded with Rh and Co3O4 co‐catalysts, respectively. These improvements are attributed to the reduced particle size and enhanced crystallinity of the material as well as the slower decay of photogenerated carriers on a nanosecond to sub‐microsecond time range. Further optimization of this flux‐assisted method together with suitable surface modification is expected to produce high‐quality YTOS crystals with superior photocatalytic activity. [ABSTRACT FROM AUTHOR]

Y2Ti2O5S2 (YTOS), an oxysulfide material, has attracted attention as a photocatalyst due to its optical absorption at wavelengths up to 650 nm, and its ability to split water into hydrogen and oxygen. However, the performance of YTOS in photocatalytic water splitting has remained low. One important factor accounting for this poor activity is the absence of highly efficient active sites. Surface modification with oxygen‐evolution co‐catalysts is indispensable for enhancing the activity and durability of non‐oxide narrow‐bandgap photocatalysts. Herein, we report the preparation of cobalt oxide (Co3O4)‐loaded YTOS for photocatalytic oxygen evolution. The Co3O4 co‐catalyst was loaded by thermal decomposition of cobalt nitrate. The as‐obtained sample showed significantly enhanced activity in the oxygen evolution reaction compared with unmodified or IrO2‐loaded YTOS. Transient absorption spectroscopy revealed that the Co3O4 co‐catalyst captured holes and promoted charge separation, which accounted for the enhanced activity. [ABSTRACT FROM AUTHOR]