BiOCI Sub-Microcrystals Induced by Citric Acid and Their High Photocatalytic Activities

Bismuth oxychloride (BiOCI) sub-microcrystals with tunable morphologies from nanoflakes to hollow microspheres (HMSs) have been synthesized by hydrolyzing a hierarchical precursor (BiCI3) in a solution of water and ethanol with the addition of poly(vinylpyrrolidone) (PVP) and citric acid. The obtained BiOCI possessed sub-microcrystals from single crystals to polycrystals. The formation of the nestlike and hollow structure was found to be induced by citric acid and PVP. The crystal growth and morphology control of BiOCI were explored. Interestingly, citric acid was utilized both as a crystal-growth-inducing agent and a structure-directing agent. The morphology and compositional characteristics of BiOCI were investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman, and UV-vis spectra. The photocatalytic activities of BiOCI with different structures have also been investigated by the degradation of Rhodamine-B (RhB) dye under ultraviolet light irradiation. The as-prepared BiOCI exhibited much higher photocatalytic activity than the comzmon one. In particular, the three-dimensional hierarchical structure such as microflowers and HMSs can effectively improve photocatalytic activity. The results show that BiOCI sub-microcrystals have promise as a novel material for photocatalytic applications.