Enhanced photocatalytic performance and mechanism of Ag-decorated LaFeO3 nanoparticles

Spherical LaFeO 3 nanoparticles with an average size of 35 nm were synthesized by a polyacrylamide gel route. Ag nanoparticles of 8–18 nm in size were decorated onto LaFeO 3 particle surface by a chemical reduction method to yield Ag–LaFeO 3 composites. The samples were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, and photoluminescence spectroscopy. It is found that LaFeO 3 particles have two bandgap energies of 2.59 and 2.24 eV, which undergo almost no change when decorated with Ag nanoparticles. photoluminescence spectra demonstrate that the decoration of LaFeO 3 particles with Ag nanoparticles leads to a decreased recombination rate of photogenerated electrons and holes. The photocatalytic activity of the samples was evaluated by degrading Rhodamine B under simulated-sunlight irradiation. Compared to bare LaFeO 3 particles, Ag–LaFeO 3 composites exhibit an obviously enhanced photocatalytic activity. The formed •OH was examined by photoluminescence spectroscopy using terephthalic acid as the •OH scavenger, revealing an enhanced yield on the irradiated Ag–LaFeO 3 composites. To clarify the role of active species in the photocatalysis, the effect of ammonium oxalate (h + scavenger), ethanol (•OH scavenger), benzoquinone (•O 2 − scavenger), and N 2 on the Rhodamine B degradation as well as the •OH yield was investigated. Based on the experimental results, •OH and •O 2 − are suggested to be the main active species causing the dye degradation. Graphical Abstract