Controlled synthesis of barium chromate multi-layered microdiscs and their photocatalytic activity

BaCrO4 microdiscs composed of multi-layered microplates were successfully synthesized by a facile oxalate-assisted precipitation method for the first time. Herein, the oxalate ion helps slow down the nucleation rate of BaCrO4 crystals by complexing with the barium ion and offers control over the crystal growth and self-assembly processes via selective adsorptions probably on the facets containing elevated barium ions of the growing BaCrO4 crystals. Based on the time-dependent experiments, the dissolution–recrystallization–self-assembly process has been proposed for a possible formation mechanism of the multi-layered microdiscs. A preliminary photocatalytic study suggests that the multilayered microdiscs preferentially degrade methyl orange over methylene blue and phenol due to their positive surface charge. Further investigation on the MO degradation performance under UV and visible irradiations clearly shows that the three-dimensional hierarchical structure provides better photocatalytic activity than its low-dimensional counterpart, potentially due to its higher optical absorption ability originating from the unique morphology. The synthetic method developed in this work not only provides a one-step, facile and effective control over the morphology of BaCrO4, but also offers an alternative approach toward the design of efficient photocatalytic materials.