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

As different light-driven photocatalysts, Zn0.28Cd0.72S and TiO2 showed different properties in the photocatalytic process. In this paper, the comparison was carried out among the properties of Zn0.28Cd0.72S-visible, Zn0.28Cd0.72S-UV, and TiO2-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 Zn0.28Cd0.72S-UV system, 02, center dot OH, and holes played a bigger role, whereas in the TiO2-UV system, center dot OH and holes predominated; in the Zn0.28Cd0.72S-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.