Synthesis and photocatalytic degradation ability evaluation for rhodamine B of ZnO@SiO2 composite with flower-like structure

Abstract

ZnO@SiO₂ composite with flower-like structure was successfully prepared with molar ratio of ZnO/SiO₂ = 1:1 based on the optimized synthesizing parameters of spherical SiO₂ and flower-like ZnO. SiO₂ particles were coated on the flower-like ZnO to form a homogeneous film through the multidimensional polycondensation of Si(OH)₄. The photocatalytic degradation ability of ZnO@SiO₂ composite for rhodamine B (RhB) obtained at different ZnO/SiO₂ molar ratio and the comparison to that of flower-like ZnO showed that ZnO@SiO₂ composite with ZnO/SiO₂ molar ratio of 1:1 displayed a relatively good photocatalytic degradation ability to degrade RhB, but it was weaker than that of flower-like ZnO. Twenty millilitres of RhB solution at a concentration of 15 mg·L^-1 could be completely degraded by 300 mg flower-like ZnO powder within 3 h, while the degrading efficiency was only 82.5% by 300 mg ZnO@SiO₂ composite. But ZnO@SiO₂ composite showed a better photocatalytic activity than flower-like ZnO at a lower pH value of 4.5.