New Insight into Visible-Light-Driven Photocatalytic Activity of Ag-Loaded and Oxygen Vacancy-Containing BiOBr(OV)/BiOI0.08 Microspheres

A series of Ag-loaded and oxygen vacancy (OV)-containing BiOBr(OV)/BiOI0.08 (Ag/BiOBr(OV)/BiOI0.08) photocatalysts with varying Ag loading levels were synthesized via the solvothermal–photocatalytic reduction method. As confirmed via optical, photoelectrochemical, and 4-chlorophenol photodegradation experiments, a low Ag loading level significantly enhanced the photogenerated charge carrier (PCC) transfer on the BiOBr(OV)/BiOI0.08 semiconductor surface and the performance of Ag/BiOBr(OV)/BiOI0.08 photocatalysts, which was attributable to the synergism between the effect of OVs and the localized surface plasmon resonance (LSPR) of Ag nanoparticles. Additionally, BiOBr(OV)/BiOI heterojunctions facilitated efficient visible-light harvesting and PCC separation. As indicated by finite-difference time-domain (FDTD) simulations and density functional theory (DFT) calculations, the electric field intensity in the “hot spots” generated at the interface between the BiOBr(OV)/BiOI0.08 semiconductor and Ag nanoparticles increased by more than eight times, and the presence of OVs and Ag atomic clusters introduced impurity energy levels in the semiconductor bandgap, improving PCC separation and Ag/BiOBr(OV)/BiOI0.08 photocatalytic efficiency. However, an increase in silver loading renders the composite metallic, suggesting a reduction in its photocatalytic performance. This work provides new insights for designing highly active visible light catalysts and contributes to the development of more efficient plasmonic catalysts.