Enhanced p-cresol photodegradation over BiOBr/Bi₂O₃ in the presence of rhodamine B

Abstract

Bismuth oxide is a visible-light activated photocatalyst that is adversely affected by a high rate of electronhole recombination. To mitigate this, BiOBr/Bi 2 O 3 composites were synthesized where BiOBr formed submicron thick platelets at the surface of the Bi 2 O 3 particles. XRD measurements show the preferential formation of a (110)-facetted BiOBr overlayer which can be attributed to the commensurate structure of this plane with the (120) plane of Bi 2 O 3 . The photodegradation of p-cresol and RhB was studied as representative of an organic pollutant and a dye, respectively. The composite with 85% BiOBr/Bi 2 O 3 exhibited the highest photoactivity for both molecules. Its higher activity compared to that of either Bi 2 O 3 or BiOBr alone, or a mechanical mixture with the same composition, supports the hypothesis that the formation of an hetero-epitactic interface between BiOBr and Bi 2 O 3 is instrumental in reducing electron-hole pair recombination. Interestingly, in mixtures of p-cresol and RhB, the rate of p-cresol photodegradation was enhanced but that for RhB was decreased compared to the pure solutions. This is not caused by competitive adsorption of the molecules but rather by excitation transfer from RhB to the co-adsorbed p-cresol. Therefore, the RhB degradation by deethylation, which is a surface reaction, is suppressed and only the reaction channel through attack of the OH$ radical at the aromatic chromophore remains open.

Toward Expanding the Optical Response of Ag2CrO4 and Bi2O3 by Their Laser-Mediated Heterojunction

“…The calculations show that the E g of the pristine A has a similar value as the one conventionally obtained for Ag 2 CrO 4 when it is synthesized by the coprecipitation method, the pristine B shows an E g value that corresponds to a combination of the one for α-Bi 2 O 3 and Bi 2 O 2 CO 3 , 2.80 and 3.42 eV, respectively, , and in the case of the mixtures, no E g entirely match those values belonging to the pristine A or B, which indicates that the grinding process effectively allows the formation of heterojunctions between the composing semiconductors.…”

“…Besides, because these semiconductors are characterized by absorption spectra governed mainly by indirect allowed electronic transitions, the optical band gap (E g ) was extracted from the Kubelka−Munk equation αhν = C(hν − E g ) 2 , where α represents the absorption coefficient, hν is the photon energy, and C is a proportionality constant. 42 The calculations show that the E g of the pristine A has a similar value as the one conventionally obtained for Ag 2 CrO 4 when it is synthesized by the coprecipitation method, 42 the pristine B shows an E g value that corresponds to a combination of the one for α-Bi 2 O 3 and Bi 2 O 2 CO 3 , 2.80 and 3.42 eV, respectively, 43,44 and in the case of the mixtures, no E g entirely match those values belonging to the pristine A or B, which indicates that the grinding process effectively allows the formation of heterojunctions between the composing semiconductors.…”

Mechanistic Insights into Photodegradation of Organic Dyes Using Heterostructure Photocatalysts

“…On the other hand, Au-ZnO NRs showed a six-fold increase of AQY over bare ZnO NRs in the visible region, which can be attributed to the plasmonic effect of Au. In addition, the BiOBr/Bi 2 O 3 heterostructures were demonstrated for photodegradation of an RhB/p-cresol mixture [45]. The SEM image showed that the composites comprised BiOBr platelets arranging in whorls perpendicular to the Bi 2 O 3 surface (Figure 4c).…”

Enhanced performance for Rhodamine B degradation over SnO2/BiOBr photocatalyst

“…Recent developments of semiconductor BiOBr as photocatalyst for wastewater treatment have attracted much attention. [1,2] It was demonstrated in a number of studies that composite metallic oxide/BiOBr semiconductor photocatalysts produced an evident improvement in a series of photocatalytic reaction rates in contrast to pure BiOBr semiconductor counterparts, such as Bi 2 O 3 , [3] ZnO, [4] TiO 2 , [5] Fe 3 O 4 , [6] and WO 3 , [7] have proven to be effective counterparts in fabricating heterojunctions with BiOBr, all of which have shown excellent photocatalytic properties under visible light. However, there are relatively few studies devoted to SnO 2 in the preparation of heterojunctions with BiOBr.…”