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So-called Z-scheme systems permit overall water splitting using narrow-bandgap photocatalysts. To boost the performance of such systems, it is necessary to enhance the intrinsic activities of the hydrogen evolution photocatalyst and oxygen evolution photocatalyst, promote electron transfer from the oxygen evolution photocatalyst to the hydrogen evolution photocatalyst, and suppress back reactions. The present work develop a high-performance oxysulfide photocatalyst, Sm2Ti2O5S2, as an hydrogen evolution photocatalyst for use in a Z-scheme overall water splitting system in combination with BiVO4 as the oxygen evolution photocatalyst and reduced graphene oxide as the solid-state electron mediator. After surface modifications of the photocatalysts to promote charge separation and redox reactions, this system is able to split water into hydrogen and oxygen for more than 100 hours with a solar-to-hydrogen energy conversion efficiency of 0.22%. In contrast to many existing photocatalytic systems, the water splitting activity of the present system is only minimally reduced by increasing the background pressure to 90 kPa. These results suggest characteristics suitable for applications under practical operating conditions. Photocatalytic water splitting systems using Sm2Ti2O5S2, a visible light-active oxysulfide, exhibited low efficiencies due to low intrinsic photoactivity and rapid back reaction. Here, the efficiency was greatly improved by refining the preparation of photocatalysts and electron mediators [ABSTRACT FROM AUTHOR]

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]

Metal organic frameworks (MOFs) have received increasing attention in the field of photoredox catalysis, mainly due to the advantages of the highly porous nanostructure and tunable semiconducting properties. Thus, the essential roles of photocatalysis by MOF can be conventionally optimized toward addressing the environment and energy issues. In this review, the fundamental of the photocatalytic MOF is initially discussed. A range of the solar-driven applications by photocatalytic MOF are highlighted, including water contamination degradation, water splitting, CO 2 reduction and organosynthesis. In each chapter, a series of systematic investigations is presented, also involving a few recent results and unique phenomena that bestowed by the photocatalytic MOFs. The future prospects and challenges to use MOFs for each photocatalysis application are proposed. [ABSTRACT FROM AUTHOR]