The band gap, conduction band, and valence band of catalysts along with the photocatalytic process, it was essential to analyze the change of photocatalytic activity in the perspective of energy band. The valence band and conduction band of a semiconductor at the point of zero charge may be calculated by the following equation: ECB = – Ee – 1/2Eg (five) EVB = ECB Eg (six)where EVB and ECB are the positions of leading valence band and bottom conduction band, could be the absolute electronegativity on the semiconductor, Ee will be the regular electrode prospective of hydrogen (four.5 eV), and Eg may be the semiconductor band gap value. The conduction band and valence band positions of your sample have been calculated in the Eg band gap worth of diffuse reflection evaluation combined with all the above formula, as shown in Table three.Table three. Band structure parameters of samples (unit: eV). Sample BiOI BiOBr0.15 I0.85 BiOBr Eg 1.87 1.89 2.86 EV two.375 two.415 three.one hundred EC 0.505 0.525 0.Figure 11 showed the photodegradation mechanism and band structures of BiOBr0.15 I0.85 and BiOI determined by the above evaluation. The position of the conduction band bottom of pure BiOI was reduced than the reduction potential of O2 / 2- (0.33 eV) and also the position of your valence band top rated was higher than the oxidation prospective of OH- / H (two.38 eV); only holes (H) and a little volume of hydroxyl radicals ( H) may very well be generated within the photocatalytic approach, resulting in the poor photocatalytic degradation overall performance ofNanomaterials 2021, 11,12 ofBiOI [45,46]. Clearly, the widening on the band gaps of BiOBr0.15 I0.85 reduced the absorption of visible light as well as the downward shift of the valence band position made extra oxidizing holes and hydroxyl radicals, which play an important part in degradation. Alternatively, the extended electron-hole DiBAC4 References composite path led to additional efficient separation of photogenerated carriers in the wider gap of BiOBr0.15 I0.85 , consistent with the PL spectral analysis. As a result, the photocatalytic overall performance was optimized by optimizing redox possible and blocking carrier recombination.Figure 11. Schematic diagram of your BiOI and BiOBr0.15 I0.85 reaction mechanism for photocatalytic degradation of RhB.To additional investigate the photocatalytic mechanism proposed above, the transient photocurrent responses in the BiOBr, BiOI, and BiOBr0.15 I0.85 had been measured for many on-off cycles to clarify the interfacial charge separation under intermittent Xe lamp irradiation (Figure 12). It may be clearly seen that all samples showed a stabilized and reversible photocurrent response. The BiOBr0.15 I0.85 exhibited the biggest photocurrent density, revealing less recombination along with a IL-31 Protein Protocol longer lifetime of photogenerated carriers, which indicates that charge separation efficiency might be enhanced by effectively forming strong answer structure [47]. The enhancement of separation efficiency of photoinduced electron-hole pairs ought to be an important source of superb photoactivity of bandmodulated BiOBr0.15 I0.85 nanosheets, which delivers a promising and economical system for the design and style and development of photodegradation catalysts [48].Figure 12. Photocurrent responses of the BiOBr, BiOI, and BiOBr0.15 I0.85 in 0.five M Na2 SO4 aqueous solutions vs. Ag/AgCl.Nanomaterials 2021, 11,13 of4. Discussion In summary, 2D BiOBrX I1-X nanoplates were successfully synthesized by a very simple hydrothermal approach. The photocatalysis performance of these as-prepared samples was evaluated by RhB degradation under visi.
