Synergistic interfacial engineering of SrTiO3-x/ZnxNi1-xIn2S4 hetero-nanofibers for enlarging the band bending and boosting photocatalytic hydrogen evolution

Synergistic interfacial engineering in heterostructures offers significant potential for enhancing photocatalytic hydrogen evolution. However, reports remain limited due to the challenges of simultaneously tuning the electronic structures of both components in heterojunctions at the nanoscale. In this work, we introduce a stepwise approach to synergistic modulate the interfacial energy band structures in a hetero-nanofiber system. SrTiO_3-x nanofibers modified through surface oxygen defect engineering, are combined with Zn_xNi_1-xIn₂S₄ via a solid solution engineered, to form SrTiO_3-x/Zn_xNi_1-xIn₂S₄ hetero-nanofibers. The band positions of SrTiO_3-x nanofibers shift upward, while those of Zn_xNi_1-xIn₂S₄ shift downward, leading to a larger conduction and valence band offset, enlarged interfacial band bending, and enhanced light absorption. The SrTiO_3-x/Zn_xNi_1-xIn₂S₄ hetero-nanofibers exhibit an enhanced built-in electric field intensity at the interface about 2–3 times compared with SrTiO₃/ZnIn₂S₄ hetero-nanofibers without synergistic interfacial engineering. These hetero-nanofibers exhibited an ultrahigh H₂ production rate of 14.79 mmol g⁻¹ h⁻¹ an improvement of approximately 11 times than SrTiO₃/ZnIn₂S₄ hetero-nanofibers and 87 times than pure ZnIn₂S₄ under the simulated solar light, and achieving a remarkable apparent quantum efficiency of 55.34 % at 350 nm. This synergistic interfacial engineering is promising for developing novel photocatalytic systems with enlarged band bending and enhanced interfacial electric field for efficient charge separation.