Abstract
In this work, hierarchical BiOBr1−xIx/BiOBr heterojunction photocatalyst with a microsphere morphology was synthesized by a facile solvothermal process. It demonstrated that the local structure of the photocatalysts was highly distorted due to the substitution of bromide ions by iodine ions. The photocatalytic properties were evaluated by the photodecomposition of aqueous phenol solution under visible-light irradiation. The results indicated that all the composite photocatalysts exhibited high photocatalytic activity. In particularly, the BiOBr1−xIx/BiOBr (x = 0.25) sample exhibited over 92% degradation efficiency of phenol within 150 min, which is 24.6 and 3.08 fold enhancement in the photocatalytic activity over the pure phased BiOBr and BiOI, respectively. Moreover, this excellent photocatalytic property can be expanded to other colorless organic contaminants, verifying the common applicability of BiOBr1−xIx/BiOBr (x = 0.25) as an excellent visible-light photocatalyst for organics decomposition. The significant improvement in the photocatalytic activity can be explained by the high efficiency of charge separation due to the enhancement in the internal electric fields and band match that comes from the local structure distortion. This work provides valuable information for the design of highly active photocatalysts toward the environmental remediation.
Highlights
Semiconductor photocatalysis has attracted tremendous interest as a green and efficient technique to carry out the degradation of organic pollutants [1] [2]
The significant improvement in the photocatalytic activity can be explained by the high efficiency of charge separation due to the enhancement in the internal electric fields and band match that comes from the local structure distortion
As shown in the enlarged X-ray powder diffraction (XRD) patterns (Figure 1(b)), when the iodine was introduced in the microspheres structures, the diffraction peaks significantly shift toward lower angles, resulting from the larger radius of I− with respect to Br− [21]
Summary
Semiconductor photocatalysis has attracted tremendous interest as a green and efficient technique to carry out the degradation of organic pollutants [1] [2]. Sun and co-workers constructed a heterostructure of BiOI(001)/Bi- OCl(010) They demonstrated that beyond achievement of lattice and band match, the shorter photogenerated electron diffusion distance in the self-in- duced internal electric fields of BiOCl slabs leads to a higher charge injection of BiOI(001)/BiOCl(010) [7]. These observations indicate that the crystal facet combination playsa key factorfor enhancing the photocatalytic. An enhanced efficiency of photocatalytic phenol degradation under visible light has been achieved over the optimal BiOBr1−xIx/BiOBr (x = 0.25) sample It elucidated that the local distortion increases due to elemental doping and heterojunction construction resulted in the spontaneous polarization enhancement and the variation in the built-in electrical field. It is believed that the design of such layered materials could bring a new common strategy to create advance photocatalytic materials for environmental remediation
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