The Ag-based SPR effect drives effective degradation of organic pollutants by BiOCOOH/AgBr composites

Abstract

The easy recombination of electron-hole pairs produced by monomeric photocatalysts under light exposure severely limits their application in wastewater treatment. Based on this, BiOCOOH/Ag/AgBr ternary photocatalysts in flower-like microspheres were controllably synthesized by precipitation photoreduction and characterized by various techniques. In addition, the effects of different molar ratio of BiOCOOH and AgBr, catalyst dose, pH and coexisting ions on the photocatalytic degradation of rhodamine B (RhB) and tetracycline (TC) were investigated. The results showed that the BOC/Ag/AgBr-0.5 composite exhibited excellent photocatalytic activity for the degradation of RhB and TC. The excellent photocatalytic activity was mainly attributed to the surface plasmon resonance (SPR) effect of metallic Ag and charge transfer mechanism between composites, thus promoting charge separation. The degradation efficiency of RhB and TC was 92.7% and 72.3% with the degradation rate constant of 0.073 and 0.023 under light irradiation of xenon lamp in 30 and 45 min, respectively, which was 6 and 2 times higher than that of BiOCOOH and AgBr. The stability studies showed that BOC/Ag/AgBr-0.5 maintained a high catalytic activity after four cycles. The results of radical capture experiments showed that h+ and ·O2– were the main reactive radicals, while ·OH played a secondary role in the photocatalytic system. Subsequently, a potential photocatalytic mechanism was proposed based on the experimental results.