Enhanced photocatalytic activity of BiFeO₃ particles by surface decoration with Ag nanoparticles

Abstract

BiFeO₃ particles with different morphologies and sizes were synthesized via a hydrothermal process, where the morphology and size was tailored by using different KOH concentrations in precursor solution. The samples prepared at n(KOH) = 3, 4.5, 6, and 7.5 M are composed, respectively, of octahedron-shaped particles (500–600 nm), cube-like particles (200–500 nm), irregular spherical agglomerates (9–16 μm) formed from disk-like grains with diameter of 1.4–2.8 μm and thickness of 0.2 μm, and cuboid-shaped particles with length-to-width ratio of 1.4:1–3.5:1 and width size ranging from 80 to 280 nm. Ag nanoparticles were deposited on the surface of BiFeO₃ particles by a chemical reduction method to produce Ag@BiFeO₃ nanocomposites. The photocatalytic activity of prepared samples was evaluated by degrading rhodamine B under simulated sunlight irradiation. It is demonstrated that Ag-decorated BiFeO₃ particles exhibit an enhanced photocatalytic activity compared to bare BiFeO₃ particles. This can be explained by the effective transfer of photogenerated electrons from the conduction band of BiFeO₃ to Ag nanoparticles and hence increased availability of holes for the photocatalytic reaction. Hydroxyl radicals were detected by the photoluminescence technique using terephthalic acid as a probe molecule and are found to be produced over the irradiated BiFeO₃ and Ag@BiFeO₃ photocatalysts; especially, an enhanced yield is observed for the latter.