Abstract: Zinc acetate is used as a raw material to synthesize the desired ZnO in hot solvent by controlling the amount of citric acid (CA) added. Notably, the amount of CA added has a significant relationship with the control of the morphology of ZnO. Spherical ZnO wrapped in nanosheets is synthesized through the secondary crystallization of Zn²⁺. The optical properties of the ZnO sample are tested through the degradation of organic pollutants. Notably, the photocatalytic properties of ZnO vary with the different amounts of CA added. Exposure of the active crystal face increases the photocatalytic activity of ZnO. In addition, the number of defects on the surface of the ZnO sample increases because of its large specific surface area, thus changing the bandgap of ZnO. Therefore, the resulting sample can respond under visible light.