Photocatalytic seawater splitting by 2D heterostructure of ZnIn2S4/WO3 decorated with plasmonic Au for hydrogen evolution under visible light

Photocatalytic H2 evolution from seawater splitting presents a promising approach to tackle the fossil energy crisis and mitigate carbon emission due to the abundant source of seawater and sunlight on the earth. However, the development of efficient photocatalysts for seawater splitting remains a formidable challenge. Herein, a 2D/2D ZnIn2S4/WO3 (ZIS/WO3) heterojunction nanostructure is fabricated to efficiently separate the photoinduced carriers by steering electron transfer from the conduction band minimum of WO3 to the valence band maximum of ZIS via constructing internal electric field. Subsequently, plasmonic Au nanoparticles (NPs) as a novel photosensitizer and a reduction cocatalyst are anchored on ZIS/WO3 surface to further enhance the optical absorption of ZIS/WO3 heterojunction and accelerate the catalytic conversion. The obtained Au/ZIS/WO3 photocatalyst exhibits an outstanding H2 evolution rate of 2610.6 or 3566.3 μmol g−1 h−1 from seawater splitting under visible or full-spectrum light irradiation, respectively. These rates represent an impressive increase of approximately 7.3- and 6.6-fold compared to those of ZIS under the illumination of the same light source. The unique 2D/2D structure, internal electric field, and plasmonic metal modification together boost the photocatalytic H2 evolution rate of Au/ZIS/WO3, making it even comparable to H2 evolution from pure water splitting. The present work sheds light on the development of efficient photocatalysts for seawater splitting.