One-step hydrothermal synthesis of hierarchical nanosheet-assembled BiOCO microflowers with a {001} dominant facet and their superior photocatalytic performance.

Using citric acid (CA) and 1,5-naphthalenedisulfonic acid (NDSA) as the structure-directing agent, a hierarchical flower-like BiOCO product is successfully prepared via a simple one-step hydrothermal synthesis, which is spirally assembled by the {001} facet-dominated nanosheets. It is testified that the additive CA plays an important inducing role in forming the chemical composition of BiOCO, the nanosized sheet-type subunits, and the exposure of the {001} facet, while the NDSA greatly improves the dispersity and porous structure of the BiOCO microflower. Due to the nano-size effect and distortion of surface Bi-O bonds, the BiOCO microflower could be excited by the visible light to exhibit a superior photocatalytic performance in the degradation of tetracycline (TC). Besides, it is found the exposed {001} facet of BiOCO would preferentially generate holes during the illumination process, thus enhancing the photooxidative activity of the BiOCO microflower. Finally, the structural and optical features of the BiOCO microflower have been discussed in detail, and its photocatalytic mechanism has also been proposed in this work.