Bismuth oxychloride (BiOCl) sub-microcrystals with tunable morphologies from nanoflakes to hollow microspheres (HMSs) have been synthesized by hydrolyzing a hierarchical precursor (BiCl3) in a solution of water and ethanol with the addition of poly(vinylpyrrolidone) (PVP) and citric acid. The obtained BiOCl 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 BiOCl 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 BiOCl were investigated by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Raman, and UV–vis spectra. The photocatalytic activities of BiOCl with different structures have also been investigated by the degradation of Rhodamine-B (RhB) dye under ultraviolet light irradiation. The as-prepared BiOCl 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 BiOCl sub-microcrystals have promise as a novel material for photocatalytic applications.
Rare earth silicate phosphors of high quantum efficiency with a stable performance are promising materials in the fields of display and illumination. The grain sizes of products synthesized via the conventional solid-state reaction method are usually too large to satisfy the requirements of color cast and extraction efficiency in high-resolution light-emitting devices (LEDs). We designed a synthetic route and successfully fabricated rare earth silicate NaGd9Si6O26(NGSO) sub-microcrystals with a size ranging from 550 to 1200 nm. The reaction mechanism and optical properties were systematically investigated. The quantum efficiency of Eu3+-activated NGSO sub-microcrystals was about 36.6%. The LED encapsulated with these sub-microcrystals showed lower color deviation and higher lumen efficiency and lumen flux compared to that with NGSO fabricated using the conventional solid state reaction method.
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