Facile Template-Free Synthesis of Bi2O2CO3 Hierarchical Microflowers and Their Associated Photocatalytic Activity

Hierarchical Bi2O2CO3 flowerlike microstructures have been synthesized for the first time using a facile, template-free, and low-temperature solution method. With an average diameter of about 3 mu m, the as-prepared Bi2O2CO3 microflowers are composed of numerous two-dimensional nanosheets with oriented terminal engagement. On the basis of electron microscopy observations, a plausible growth mechanism is proposed as a spatial self-assembly process accompanied by Ostwald ripening. The molar ratio of the initial reagents plays an Bi2O2CO3 role in determining the morphologies of the Bi2O2CO3 microstructures. UV/Vis spectroscopy is employed to analyze the band gaps of the products. Both mesopores and macropores are revealed in the Bi2O2CO3 microflowers by means of nitrogen sorption and pore-size distribution. Moreover, evaluated by the degradation of methyl orange under UV illumination, the photocatalytic performance of the Bi2O2CO3 hierarchical microflowers is almost six times higher than that of commercial Bi2O2CO3. The higher specific surface area, the meso/macropores, and the intra-electric field formed between the (Bi2O2)(2+) layer and the slabs comprising CO32- in the Bi2O2CO3 crystal structure, are believed to facilitate the separation of the photoinduced electrons and holes and thus improve the corresponding photocatalytic activity.