Effect of anisotropic conductivity of Ag2S-modified ZnmIn2S3+m (m = 1, 5) on the photocatalytic properties in solar hydrogen evolution

Abstract

3 wt% Ag₂S/Zn₅In₂S₈ (3A/Z5) and 3 wt% Ag₂S/ZnIn₂S₄ (3A/Z1) were prepared by a two-step synthesis method. The first-principles calculations revealed that the anisotropic carrier transport property of Zn₅In₂S₈ (Z5) is much stronger than that of ZnIn₂S₄ (Z1). Furthermore, unsynchronized electron and hole transport leads to higher bulk carrier separation efficiency in Z5. After accelerating the surface photocatalytic reaction rate by Ag₂S modification, the differences between 3A/Z5 and 3A/Z1 in the bulk carrier separation were further enlarged. Photoelectrochemical tests confirmed that the bulk charge separation efficiency of 3A/Z5 is 13.70%, which is 7.4 times higher than 3A/Z1 (1.84%). Because of the high bulk carrier separation efficiency, the 3A/Z5 exhibits a promising photocatalytic hydrogen production rate, reaching 3189 μmol h⁻¹ g⁻¹. Through intuitive evidence, this work proves that material with stronger anisotropic conductivity has higher bulk carrier separation efficiency, thus has the potential to exhibit high photocatalytic hydrogen production performance.