Constructing a novel AuAg/BiOBr/BaTiO3 composite via selective decoration route with enhanced visible-light photoatalytic performance

In this work, the BaTiO3 nanoparticles (hole acceptor) were firstly decorated on the surface of BiOBr nanoplates by hydrothermal method, and then AuAg alloy nanoparticles (electron acceptor) are selectively deposited on the uncovered surface of BiOBr nanoplates to form AuAg/BiOBr/BaTiO3 composite using visible-light photodeposition method. It is found that the BaTiO3 (∼55 nm) and AuAg (7–16 nm) nanoparticles are uniformly dispersed on the BiOBr surface, which are disconnected without direct contact between them. The visible-light photocatalytic degradation and reduction activity of products were evaluated using methyl orange (MO), acid orange 7 (AO7), rhodamine B (RhB) and Cr(VI) as the target reactant. After the combination of BiOBr with BaTiO3, the BiOBr/BaTiO3 composites exhibit enhanced photocatalytic activity. When the content of BaTiO3 reaches about 10%, the BiOBr/10%BaTiO3 composite exhibits best photocatalytic efficiency. Notably, the selective deposition of Au, Ag and AuAg alloy nanoparticles leads to the further enhancement of photocatalytic activity for BiOBr/10%BaTiO3 composite, and the optimal photocatalytic activity can be achieved over AuAg/BiOBr/10%BaTiO3 sample. The AuAg/BiOBr/10%BaTiO3 composite is demonstrated to be an stable photocatalyst, which also exhibits efficient synergistic photocatalytic activity for the purification of the RhB/Cr(VI) and AO7/Cr(VI) mixture. The photogenerated charges performance of products was measured by electrochemical work station. The main active species participated in the photocatalytic reaction of AuAg/BiOBr/10%BaTiO3 was detected. Based on above results, the synergistic modification mechanism of BaTiO3 and AuAg alloy nanoparticles on the photocatalytic activity of BiOBr was proposed.