Hydrothermal and post-heat treatments of TiO2/ZnO composite powder and its photodegradation behavior on methyl orange

The composite powder of TiO2/ZnO with an atomic ratio of Ti to Zn of 3/1 was prepared through sol–gel process followed by hydrothermal and post-heat treatments. The as-prepared powder was characterized in detail by means of XRD, TG/DTA, DLS, and SEM. The XRD results showed that by applying the hydrothermal process the crystallinity of the composite powder was significantly improved. The SEM and DLS results revealed no visible variations on particle morphology and size owing to the hydrothermal and post-heat treatments. The enhancement of the photocatalytic activity of the composite powder evaluated through methyl orange (MO) degradation under UV light irradiation was, therefore, attributed to its high crystallinity that was achieved during the hydrothermal process under a rather low temperature.