Integrating dual-defects and the heterojunction in ZnIn2S4-x/g-C3N4-x composites induces breaking-symmetry for photocatalytic hydrogen production

Solar photocatalysis presents a promising solution to address both energy demands and the associated environmental concerns. However, the rapid combination of photogenerated charges internally and on the material's surface seriously affects the photocatalytic efficiency. In this work, N and S double-defected heterojunction ZIS(Sv)/CNNv composites were prepared by thermal polymerization and hydrothermal methods, and the defects present in the materials caused the symmetry of the crystal structure of the materials to be broken. Femtosecond transient absorption spectroscopy indicated that material defects induce internal symmetry breaking, generating shallow trapping states that decelerate the photogenerated charge recombination. The configuration attributed to the heterojunction produces a differentiated interfacial component, so that the interfacial symmetry is broken and an interfacial electric field is formed, accelerating the charge migration. This study offers a holistic approach by breaking symmetry to regulate charge dynamics within and across materials.