Specific Analyses of the Active Species on Zn0.28Cd0.72S and TiO₂ Photocatalysts in the Degradation of Methyl Orange

As different light-driven photocatalysts, Zn 0.28 Cd 0.72 S and TiO 2 showed different properties in the photocatalytic process. In this paper, the comparison was carried out among the properties of Zn 0.28 Cd 0.72 S-visible, Zn 0.28 Cd 0.72 S-UV, and TiO 2 -UV light systems in the degradation of methyl orange. After the addition of different types of active species quenchers and the results detected by electron spin resonance, a photoluminescence technique, and a photometric method, it was found that, in the Zn 0.28 Cd 0.72 S-UV system, O 2, •OH, and holes played a bigger role, whereas in the TiO 2 -UV system, •OH and holes predominated; in the Zn 0.28 Cd 0.72 S-visible light system, O 2 and holes contributed to the degradation. The differences between the two catalysts lead us to realize the active species and the degradation mechanism in photocatalytic process.