Prussian blue analogue K2Zn3[Fe(CN)6]2 quasi square microplates: large-scale synthesis and their thermal conversion into a magnetic nanoporous ZnFe2−xO4–ZnO composite

Abstract

Prussian blue analogue K₂Zn₃[Fe(CN)₆]₂·xH₂O microplates were synthesized via a hydrothermal-assisted precipitation method in the mixed solvent of isopropanol and deionized water at 120 °C for 24 h. The as-synthesized products were identified as a pure phase by X-ray diffraction (XRD). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that single-crystalline quasi square microplates with a fairly uniform morphology were successfully prepared. The average thickness and side length of the microplates were about 160 nm and 750 nm, respectively. The effects of the ratio of (CH₃)₂CHOH/H₂O in the reaction system and the surfactant (polyvinyl pyrrolidone, PVP) on the morphology of the products were investigated. The experimental results showed that PVP and the solvent isopropanol played important roles in the formation of the uniform microplates. A magnetic nanoporous ZnFe_2−xO₄–ZnO composite could be obtained from K₂Zn₃[Fe(CN)₆]₂·xH₂O microplates after calcination at 500 °C. The composite showed a good photocatalytic property in the degradation of rhodamine B and could be easily separated from the reaction mixture through magnetic separation.