Self-assembly of Bi2WO6 square nanoplates into hierarchical structures

Bi2WO6 hierarchical structures constructed by a number of square nanoplates of average approximately 70 nm in side length and approximately 25 nm in thickness have been synthesized by a hydrothermal method at 180 degrees C. The single-crystal subunit nanoplates with (002) as their two-dimensional (2D) surfaces assembled orderly using both their edges and faces into free-standing films. It was found that the self-assembled growth of these hierarchical structures strongly depended on surfactant Cetyl Trimethyl Ammonium Bromide (CTAB), the amounts of the starting materials and the molar ratio of precursors (Bi3+ to WO4(2-)), etc. The growth mechanism was discussed based on the comparative experimental results.