Enhanced photocatalytic and photo-Fenton catalytic activity of BiFeO3 polyhedron decorated by AuAg alloy nanoparticles

AuAg/BiFeO3 composite was successfully fabricated through a hydrothermal method followed by a photodeposition process. It is found that the AuAg alloy nanoparticles with the diameter of 7–23 nm were uniformly decorated on the polyhedral BiFeO3 particles, and AuAg/BiFeO3 composite exhibits stronger light absorption in the visible light region than bare BiFeO3 owing to the SPR effect of AuAg alloy nanoparticles. Acid orange 7 (AO7), phenol and Cr(VI) were employed as target pollutants to estimate the photocatalytic degradation and reduction properties of AuAg/BiFeO3 under visible light and simulated sunlight illumination. The results reveal that the photocatalytic property of BiFeO3 in the decomposition of organics (AO7 and phenol) and reduction of Cr(VI) can be remarkably improved after the decoration of AuAg alloy nanoparticles. Furthermore, the photo-Fenton catalytic activity of AuAg/BiFeO3 composite toward the decomposition of phenol was also estimated under illumination of simulated sunlight, which suggests that the composite exhibits obvious enhanced photo-Fenton catalytic degradation activity in comparison to pure BiFeO3. On the other hand, AuAg/BiFeO3 composite has favorable photocatalytic and photo-Fenton catalytic recyclability. The photoluminescence and photoelectrochemical measurements demonstrate that AuAg/BiFeO3 composite reveals enhanced separation and migration of photogenerated electrons and holes. The possible catalytic mechanism for AuAg/BiFeO3 composite was proposed according to above experiments.