Lee SH  Jeong YJ  Lee JM  Kim DS  Bae EJ  Hong SS  Lee GD

Vol. 25,  No. 1, pp. 46-55, Mar.  2019
10.7464/ksct.2019.25.1.046

Sulfide Photocatalyst Rhodamine B Photocatalytic degradation Reaction mechanism

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CdS and CdZnS/ZnO materials were prepared using precipitation method and used as photocatalysts for the photocatalytic degradation of rhodamine B (RhB) under visible light irradiation. The prepared photocatalysts were also characterized by XRD and UV-vis DRS. The results indicated that the photocatalysts with intended crystalline structures were successfully obtained and both the CdS and CdZnS/ZnO can absorb visible light as well as UV. The photocatalytic activities were examined with the addition of scavenger for various active chemical species and the difference of reaction mechanisms over the catalysts were discussed. The CH3OH, KI and p-benzoquinone were used as scavengers for ㆍOH radical, photogenerated positive hole and ㆍO2 - radical, respectively. The CdS and CdZnS/ZnO showed different photocatalytic degradation mechanisms of RhB. It can be postulated that ㆍO2 - radical is the main active species for the reaction over CdS photocatalyst, while the photogenerated positive hole for CdZnS/ZnO photocatalyst. As a result, the predominant reaction pathways over CdS and CdZnS/ZnO photocatalysts were found to be the dealkylation of chromophore skeleton and the cleavage of the conjugated chromophore structure, respectively. The above results may be mainly ascribed to the difference of band edge potential of conduction and valence bands in CdS, CdZnS and ZnO semiconductors and the redox potentials for formation of active chemical species.