A New p-Metal-n Structure AgBr-Ag-BiOBr with Superior Visible-Light-Responsive Catalytic Performance

A novel visible-light-driven AgBr-Ag-BiOBr photocatalyst was synthesized by a facile hydrothermal method. Taking advantage of both p-n heterojunctions and localized surface plasmon resonance, the p-metal-n structure exhibited a superior performance concerning degradation of methyl orange under visible-light irradiation (lambda> 420 nm). A possible photodegradation mechanism in the presence of AgBr-Ag-BiOBr composites was proposed, and the radical species involved in the degradation reaction were investigated. HO2-/O-2(-) played the same important role as (OH)-O-center dot in the AgBr-Ag-BiOBr photocatalytic system, and both the electron and hole were fully used for degradation of organic pollutants. A dual role of metallic Ag in the photocatalysis was proposed, one being surface plasmon resonance and the other being an electron-hole bridge. Due to the distinctive p-metal-n structure, the visible-light absorption, the separation of photogenerated carriers and the photocatalysis efficiency were greatly enhanced.