Electrodeposition and Photocatalytic Selectivity of ZnO/Methyl Blue Hybrid Thin Films

Abstract

ZnO/methyl blue hybrid thin films were successfully electrodeposited from an oxygen-saturated aqueous solution of ZnCl2 containing methyl blue (MB) as a structure-directing agent. The addition of MB promotes the crystal growth of ZnO and thus affects the crystallographic orientation and the surface morphology of the hybrid film. The electrodeposited hybrid thin films show porous morphology and hexagonal wurtzite crystalline structure. After extracting MB by dipping the hybrid film in a dilute base solution, the resulting porous film exhibits satisfied photocatalytic activity to degrade MB and eosin Y (EY). And the photodegradation apparent rate constant for MB is almost 5.5 times higher than that of EY. The high photodegradation selectivity to MB is attributed to the synergetic effect that the porous ZnO film obtained by extracting MB from ZnO/MB hybrid thin film adsorbs MB more favorably than EY. This interesting result could shed some light on the application of this technology for the selective degradation of organic pollutants.