Preparation of Z-scheme Au-Ag2S/Bi2O3 composite by selective deposition method and its improved photocatalytic degradation and reduction activity

Abstract

In this work, Z-scheme Ag2S/Bi2O3 composites were fabricated through the precipitation of Ag2S nanoplates on the surface of Bi2O3 microrods. Consequently, Au nanoparticles were selectively deposited on the Ag2S nanoplates surface to obtain.Au-Ag2S/Bi2O3 composites using near-infrared light photodeposition method. The characterization results indicate that the Ag2S nanoplates were uniformly anchored on Bi2O3 surface, and Au nanoparticles were highly dispersed on the surface of Ag2S nanoplate instead of Bi2O3. Acid orange 7 (AO7), Rhodamine B (RhB) and Cr(VI) were chosen as model reactant for the evaluation of photocatalytic degradation and reduction activity of the products under simulated sunlight irradiation. After the decoration of Ag2S nanoplates, the photocatalytic activity of Ag2S/Bi2O3 is much higher than that of bare Bi2O3, and the optimal catalytic efficiency is achieved by 12 %Ag2S/Bi2O3 sample. More importantly, the photocatalytic activity of 12 %Ag2S/Bi2O3 sample can be further enhanced by the selective decoration Au nanoparticles on the Ag2S nanoplates. Among the ternary composites, 2Au-12 %Ag2S/Bi2O3 sample with the Au content of 2% exhibits highest catalytic efficiency for 60 min (AO7: 96%; RhB: 56%; Cr(VI): 65%). The possible mechanism for the improvement of the photocatalytic activity of Bi2O3 by Ag2S and Au decoration was proposed.