Effect of calcinations of TiO2/ZnO composite powder at high temperature on photodegradation of methyl orange

The TiO2/ZnO composite powder with an atomic molar ratio of Ti to Zn of 1/1 was prepared via sol–gel process followed by ammonia treatment with NH3 mass fractions of 0%, 7%, and 28% and thermal calcinations at temperatures of 500, 600, and 700 °C in air. The as-prepared powder was characterized through TGA, XRD, FTIR, DLS, SEM, EDS, and HRTEM, and its photocatalytic performance was evaluated by photodegradation of methyl orange. The results showed that with the increase of the calcining temperature the composite powder showed high crystallinity and rather rough surface and hence an increase of photocatalytic activity. By applying ammonia treatment, both the chemical reaction and particle crystallization were inhibited. In addition, the particle size of the composite powder was definitely reduced. As a result, the photocatalytic performance of the composite was successfully improved.