A facile and environment friendly approach to synthesis of unique hierarchical BiOCl flowery microspheres(FMs)using a biodegradable surfactant polyvinyl alcohol(PVA)was reported herein for the first time.Compared to the BiOCl nanosheets synthesized in the absence of PVA,hierarchical BiOCl FMs consist of large amounts of interwoven polycrystalline nanosheets that assemble into a porous flowery structure.The formation mechanism of the hierarchical BiOCl FMs was also proposed,whereby PVA was believed to play a key role in the crystal growth and the formation of the final microstructures.Compared with TiO2-P25 and BiOCl nanosheets,hierarchical BiOCl FMs displayed remarkably enhanced photocatalytic activity,and20 mg of BiOCl FMs could completely degrade 50 mL of methyl orange solution(20 mg/L)within 30 min under UVlight irradiation.According to the comprehensive analysis,it can be concluded that the larger specific surface area,porosity,suitable band gap,and the enhanced light absorption capacity may contribute to the remarkably enhanced photocatalytic activity.This facile and green approach to fabricating hierarchical BiOCl FMs would give vital clues to develop new route for synthesizing other hierarchical structured materials. A facile and environment friendly approach to synthesis of unique hierarchical BiOCl flowery microspheres (FMs) using a biodegradable surfactant polyvinyl alcohol (PVA) was reported herein for the first time. Compared to the BiOCl nanosheets synthesized in the absence of PVA, hierarchical BiOCl FMs consist of large amounts of interwoven polycrystalline nanosheets that assemble into a porous flowery structure. The formation mechanism of the hierarchical BiOCl FMs was also proposed, so PVA was believed to play a key role in the crystal growth and the formation of the final microstructures. Compared with TiO2-P25 and BiOCl nanosheets, hierarchical BiOCl FMs displayed remarkably enhanced photocatalytic activity, and 20 mg of BiOCl FMs could completely degrade 50 mL of methyl orange solution (20 mg / L) within 30 min under UVlight irradiation. According to the comprehensive analysis, it can be concluded that the larger specific surface area, porosity, suitable band gap, and the enhanced light absorption ca pacity may contribute to the remarkably enhanced photocatalytic activity. This facile and green approach to fabricating hierarchical BiOCl FMs would give vital clues to develop new route for synthesizing other hierarchical structured materials.