Meiting Li,Bingxin Yuan,Chi Zhang,Jia Li,Xuejiao Wang
Hierarchical BiOCl/BiOI and BiO(Cl,I) photocatalysts were obtained via a solution-phase reaction for visible-light-driven elimination of aqueous pollutants, where the phase/morphology evolution, relationship between energy band/microstructure structure and photocatalytic properties, and photoreaction mechanism can be deciphered in detail. It was well-documented that the R = 8:1 BiOCl/BiOI heterojunctions with a coherent interface of Bi and O atoms showed a relatively strong redox capacity owing to their rapid Z-scheme charge transfer and large interfacial contact and eventually degraded ∼92.52% and 96.57% of rhodamine B (RhB) and tetracycline (TC) molecules under 10 min of visible light irradiation, which was larger than those of bare BiOCl and BiOI. However, their poor photocatalytic stability was proved to be unfavorable to practical applications. The best BiOCl0.88I0.12 solid solutions separately elucidated the optimal RhB and TC removal efficiency of ∼99.97% and 97.54% after 10 and 6 min of illumination, and it still maintained a high photodegradation efficiency toward RhB after five consecutive runs. The exceptional photocatalytic performance is cogoverned by the characteristics of in situ generated oxygen vacancies and defect energy levels.
Graphical In this paper, heterojunction photocatalyst TiO 2 @BiOCl-BiOI was successfully synthesized by composite modification method combined with sol-gel method, and it was applied to the degradation of CR. Thanks to the heterostructure structure, TiO 2 @BiOCl-BiOI showed excellent photocatalytic performance for CR under simulated sunlight, with a removal rate of 96.45 %. After 5 times of recycling, the removal rate of CR by TiO 2 @BiOCl-BiOI is still higher than 87 %. Under the action of ⋅O − 2 , h + and ⋅O, CR is oxidized to H 2 O, CO 2 and other harmless substances. TiO 2 @BiOCl-BiOI heterostructure photocatalyst with high photocatalytic activity was prepared by the composite modification and sol-gel procedure. TiO 2 nanoparticles highly dispersed on the surface of TiO 2 @BiOCl-BiOI, which provides sufficient active sites for the photocatalytic degradation process. The photodegradation performance of the photocatalyst was evaluated by the removal rate of Congo Red. The researches showed that the degradation effect of TiO 2 @BiOCl-BiOI for Congo Red is significantly stronger than that of TiO 2 and BiOCl-BiOI, which is mainly due to the type-II heterojunction structure of TiO 2 @BiOCl-BiOI and its enhanced visible-light response. The experiments of free radical capture indicated that ⋅ and are the main active species in the photocatalytic degradation system. This study showed that TiO 2 @BiOCl-BiOI can almost completely degrade Congo Red under simulated sunlight, making it the harmless substances such as H 2 O and CO 2 .
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