Nanostructured hexahedron of bismuth ferrite clusters: delicate synthesis processes and an efficient multiplex catalyst for organic pollutant degradation

Abstract

A novel bismuth ferrite, with the simultaneous formation of nanostructured clusters and controllable morphologies, was fabricated using a delicate synthesis process. By carefully controlling all processes from co-precipitation at a low temperature in water to hydrothermal treatment in methanol/water co-solvent system, nanostructured bismuth ferrite clusters with controllable morphologies composed of small bismuth ferrite crystals (∼25 nm) could be obtained. The fast crystal growth of the bismuth ferrites has been successfully hindered and a relatively pure mullite (Bi₂Fe₄O₉) structure of the nanostructured bismuth ferrite clusters could be obtained. Their morphologies could be cube-, cuboid- and plate-like shapes with a side length of ∼400 nm, a height of ∼600 nm and a thickness of ∼80 nm. The resulting nanostructured bismuth ferrite clusters show good crystallinity, uniform elemental distributions, high chemical stability, good dispersity, reusability, and a narrow bandgap of ∼2.1 eV. They have remarkable multiplex catalytic activities in the degradation of methyl orange (MO) through visible-light photo-Fenton oxidation, dark Fenton-like reaction and solar photocatalysis. Under visible-light illumination, 99% of MO could be removed in 80 min. Without illumination, 96% of MO could be removed in 4 h. A plausible mechanism of the multiplex catalytic activities is proposed.