Visible-light absorptivity of a zincoxysulfide (ZnOxS1-x) composite semiconductor and its photocatalytic activities for degradation of organic pollutants under visible-light irradiation

This work reports the development of a visible-light sensible photocatalyst and the photocatalytic degradation of organic pollutants under visible-light irradiation. A composite semiconductor of ZnS and ZnO was prepared through co-precipitation process of Zn(NO3)(2) in the mixed solution of aqueous Na2S and NaOH followed by calcination at 400 degrees C in N-2 atmosphere. It was revealed that the composite semiconductor was a solid solution of ZnS and ZnO, a zincoxysulfide (ZnOxS1-x) having advanced visible-light absorptivity. It was assured that the visible-light absorptivity was caused by modification of band structure while the solid solution had been prepared, thus we suggested a reasonable band structure model involved in a zincoxysulfide. To observe its photocatalytic activity under visible-light illumination, photodegradation test was done and we confirmed that zincoxysulfide showed predominant photocatalytic activity due to its superior visible-light absorptivity to pure ZnS and ZnO. (C) 2007 Elsevier B.V. All rights reserved.