Effective photocatalytic degradation of rhodamine-B over Zn-doped BaO2 and SrO2 composites under UV and sunlight irradiation

Environmental pollution due to dye industries is a major concern as it affects both aquatic and human life. Among various processes, photocatalysis involving the advanced oxidation process (AOP) that employs semi-conductor based photocatalysis is popular and this process degrades dyes into CO2 and H2O. The currently used TiO2 based photocatalysis requires ultra-violet (UV) light irradiation for activation. There is always a need for a catalyst that works under natural sunlight so that the dye degradation process is economical. Towards this objective, we have developed Zn doped metal peroxides as efficient photocatalysts towards rhodamine B (RhB) dye degradation. A new family of zinc-doped barium peroxide (Ba1-xZnxO2x = 0, 0.2, 0.4, 0.6, and 0.8) and zinc-doped strontium peroxide (Sr1−xZnxO2x = 0, 0.2, 0.4, 0.6, and 0.8) photocatalysts were prepared by the co-precipitation technique for the photocatalytic degradation of RhB under UV and natural sunlight irradiation. In particular, Ba0.4Zn0.6O2 (x = 0.6) and Sr0.6Zn0.4O2 (x = 0.4) photocatalysts exhibit higher photodegradation efficiency than the pure peroxides both under UV and sunlight irradiation. Ba0.4Zn0.6O2 and Sr0.6Zn0.4O2 photocatalysts show a degradation efficiency of 99.9% and 99.8% within 15 min and 10 min under UV light, respectively. The rate constants of degradation by doped peroxides, in particular Ba0.4Zn0.6O2 and Sr0.6Zn0.4O2, are 100 times higher than those of the parent peroxides.