Preparation, characterisation and activity evaluation of CaCO3/ZnO photocatalyst

The photocatalyst CaCO3/ZnO with high activity was prepared by coprecipitation method using (NH4)2CO3, Zn(NO3)2 and Ca(NO3)2 as raw materials. The photocatalyst was characterised by X-ray powder diffraction, terephthalic acid photoluminescence probing technique (TA-PL), UV–vis diffuse reflectance spectroscopy and the fluorescence emission spectra. The photocatalytic activity of the photocatalyst was evaluated by photocatalytic oxidation of methyl orange and rhodamine B. The results showed that the photocatalytic activity of the photocatalyst was much higher than that of pure ZnO. The best mole ratio of Ca/Zn in the sample was 1 : 2, and its intensity of TA-PL was the strongest. The effect of heat treatment condition on the photocatalytic activity of the photocatalyst was investigated. The best preparation condition was about 650°C for 7 h. Compared with pure ZnO, the photoabsorption wavelength range of the CaCO3/ZnO extends towards visible light and improves the utilisation of the total spectrum. The possible mechanisms of influence of CaCO3 on the photocatalytic activity of CaCO3/ZnO were also discussed.