Constructing Z-scheme AuAg@?-Bi2O3/BiOBr multi-heterojunction for efficient photocatalytic removal of dye, antibiotic and heavy metal ions: Performance and mechanism investigation

The AuAg alloy nanoparticles were decorated on the delta-Bi2O3 surface to obtain AuAg@delta-Bi2O3, then AuAg@delta Bi2O3 were hydrothermally combined with BiOBr plate to form Z-scheme AuAg@delta-Bi2O3/BiOBr. The photocatalytic activity of samples were evaluated by the removal of dyes (rhodamine B (RhB) and acid orange 7 (AO7)), tetracycline (TC) and reduction of Cr(VI) under simulated sunlight irradiation. With the decoration of delta-Bi2O3, the delta-Bi2O3/BiOBr composites exhibit higher photocatalytic activity than bare BiOBr. The optimal catalytic efficiency is achieved by 10%delta-Bi2O3/BiOBr sample, which leads to -75.7% of AO7, 84.9% of RhB and 67.5% of Cr(VI) removed after 25 min irradiation. After the introduction of AuAg nanoparticles, the photocataltyic activity of 10%delta-Bi2O3/BiOBr can be further enhanced. The removal efficiency of AO7, RhB and Cr(VI) can reach -97.9%, -97.3% and -84.5% after 25 min irradiation, respectively. The AuAg alloy nanoparticles located at the interface of Z-scheme delta-Bi2O3/BiOBr can accelerate the photogenerated charges separation over the way of a Z-scheme charge migration mechanism. In addition, AuAg alloy nanoparticles located at delta-Bi2O3 surface compensates the consumption of photogenerated charges in the direct Z-scheme delta-Bi2O3/BiOBr heterojunction due to their SPR effect, and even further promotes the separation of photogenerated charges in the composite.

Automated summary

AuAg alloy nanoparticles were decorated on delta-Bi2O3 surface to obtain AuAg@delta-Bi2O3, and then AuAg@delta-Bi2O3 were hydrothermally combined with BiOBr plate to form Z-scheme AuAg@delta-Bi2O3/BiOBr. The photocatalytic activity of samples was evaluated under simulated sunlight irradiation, and the addition of delta-Bi2O3 significantly enhanced the photocatalytic activity of BiOBr. The introduction of AuAg nanoparticles further improved the photocatalytic activity, leading to highly efficient removal of pollutants. The presence of AuAg alloy nanoparticles at the interface of Z-scheme delta-Bi2O3/BiOBr promoted the separation of photogenerated charges through a Z-scheme charge migration mechanism.