Enhanced photocatalytic degradation of organic pollutant over BiOBr/Ag composite

Lately, bismuth oxyhalide BiOX (Cl, Br, I), a new family of promising semiconductor photocatalytic materials, has drawn considerable attention. Within it, BiOBr is the most ideal candidate for its suitable band gap (2.8 eV), nontoxicity, relatively excellent photocatalytic ability and chemical stability in photocatalytic oxidation process. Therefore, many efforts have been devoted to develop the synthesis of BiOBr nanostructures which high surface-to-volume ratio is expected to increase the photocatalytic activity [1]. Silver (Ag) is an attractive material for its specific properties, such as good conductivity, chemical stability, catalytic activity and antimicrobial activity. Ag nanoparticles are used in antimicrobial applications since the antimicrobial effect of Ag ions is well known, it is being used as well as in water and air filtration. Hybrid materials of Ag nanoparticles with amphiphilic hyperbranched macromolecules are synthesized for use in surface coatings because of its antibacterial activity [2]. Newly, the deposition of Ag nanoparticles (NPs) on BiOX (X= Cl, Br, I) has been found can give a singular efficiency in destroy organic pollutants under UV or visible light irradiation. It is generally known that the noble metal/semiconductor oxide composite system could reduce the e-/h+ recombination rate due to better charge separation [3]. To prepare this compound, the prepared BiOBr was composed with 2.5 ml of AgNO3 solution. Then, freshly prepared sodium borohydride was added dropwise and then stirred for 5 hours. Eventually, the precipitate was centrifuged, washed with distilled water and dried in oven. The resulting sample was characterized using XRD, SEM, FT-IR and DRS analysis. Furthermore, the photocatalytic activity of the synthesized photocatalyst was investigated using methyl orange (MO) as a model organic pollutant. A maximum degradation efficiency of 61% has been achieved under visible light irradiation over the prepared photocatalyst. The photocatalytic performance of BiOBr/Ag photocatalyst is much higher than that of pure BiOBr.