In2S3/F-Fe2O3 type-II heterojunction bonded by interfacial S-O for enhanced charge separation and transport in photoelectrochemical water oxidation

The application of hematite(α-Fe2O3)-based photoanodes in photoelectrochemical (PEC) water oxidation has been hampered by disgusting charge recombination and difficult carrier migration. Herein, we modified indium sulfide (In2S3) nanoparticles on the surface of fluorine-doped α-Fe2O3 (F-Fe2O3) nanorods. The In2S3/F-Fe2O3 heterostructure bonded by S-O chemical bond shows a superior photocurrent density of 2.21 mA cm−2 at 1.23 V versus reversible hydrogen electrode (around 3.45 times higher than that of pristine α-Fe2O3). In-depth investigations show that In2S3/F-Fe2O3 has significantly increased donor density and decreased charge transfer resistance. Simultaneously, In2S3 decorated with S-O bond could reduce the surface defect states. Further studies of energy band location reveal the formation of type-Ⅱ heterojunction between In2S3 and F-Fe2O3. The unique heterostructure provides a powerful driving force for charge separation and transport, resulting in satisfactory bulk phase and surface separation efficiency. This work provides ideas for the design and study of multicomponent photoanodes.