Dual S-Scheme Heterojunction CdS/TiO₂/g-C₃N₄ Photocatalyst for Hydrogen Production and Dye Degradation Applications

This study investigated a ternary CdS/TiO₂/g-C₃N₄ heterojunction for degrading synthetic dyes and hydrogen production from aqueous media through visible light-initiated photocatalytic reactions. CdS, TiO₂, and g-C₃N₄ were combined in different mass ratios through a simple hydrothermal method to create CdS/TiO₂/g-C₃N₄ composite photocatalysts. The prepared heterojunction catalysts were investigated by using FTIR, XRD, EDX, SEM, and UV-visible spectroscopy analysis for their crystal structures, functional groups, elemental composition, microtopography, and optical properties. The rhodamine B dye was then degraded by using fully characterized photocatalysts. The maximum dye degradation efficiency of 99.4% was noted in these experiments. The evolution rate of hydrogen from the aqueous solution with the CdS/TiO₂/g-C₃N₄ photocatalyst remained 2910 μmol·h^-1·g^-1, which is considerably higher than those of g-C₃N₄, CdS, CdS/g-C₃N₄, and g-C₃N₄/TiO₂-catalyzed reactions. This study also proposes a photocatalytic activity mechanism for the tested ternary CdS/TiO₂/g-C₃N₄ heterojunctions.