Enhanced Photocatalytic Degradation of Methyl Orange Dye under the Daylight Irradiation over CN-TiO₂ Modified with OMS-2.

Mohamed Hassan,Guanglong Liu,Jianbo Cai,Jing Chen,Duanwei Zhu

doi:10.3390/ma7128024

Mohamed Hassan, Guanglong Liu + Show 3 more

Open Access

https://doi.org/10.3390/ma7128024

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Abstract

In this study, CN-TiO2 was modified with cryptomelane octahedral molecular sieves (OMS-2) by the sol-gel method based on the self-assembly technique to enhance its photocatalytic activity under the daylight irradiation. The synthesized samples were characterized by X-ray diffraction (XRD), UV-vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and porosimeter analysis. The results showed that the addition of OMS-2 in the sol lead to higher Brunauer-Emmett-Teller (BET) surface area, pore volume, porosity of particle after heat treatment and the specific surface area, porosity, crystallite size and pore size distribution could be controlled by adjusting the calcination temperature. Compared to the CN-TiO2-400 sample, CN-TiO2/OMS-2-400 exhibited greater red shift in absorption edge of samples in visible region due to the OMS-2 coated. The enhancement of photocatalytic activity of CN-TiO2/OMS-2 composite photocatalyst was subsequently evaluated for the degradation of the methyl orange dye under the daylight irradiation in water. The results showed that the methyl orange dye degradation rate reach to 37.8% for the CN-TiO2/OMS-2-400 sample under the daylight irradiation for 5 h, which was higher than that of reference sample. The enhancement in daylight photocatalytic activities of the CN-TiO2/OMS samples could be attributed to the synergistic effects of OMS-2 coated, larger surface area and red shift in adsorption edge of the prepared sample.

Highlights

IntroductionTiO2 has been the most widely studied material for the photocatalytic application [1,2,3,4]
Today, TiO2 has been the most widely studied material for the photocatalytic application [1,2,3,4].the practical applications of TiO2 are limited by its large band gap (3.2 eV), which can only active under the UV light irradiation [5,6,7]
The X-ray diffraction (XRD) patterns of the reference and samples at different calcinations temperatures were shown in Figure 1, Well-defined, broad, diffraction peaks corresponding to the anatase TiO2 phase were identified for the CN-TiO2 and CN-TiO2/OMS-2-400 sample

Summary

Introduction

TiO2 has been the most widely studied material for the photocatalytic application [1,2,3,4]. Combining other semiconductor or support provide a promising way to address this problem With this approach, the constituents are selected so that efficient charge transfer between them, further to reduce the rate of electron-hole recombination. Paying attention to the efficient charge transfer, has neglected the effect of specific surface area, which affects the adsorption rate and photocatalytic efficiency because pre-adsorption pollutant molecules on TiO2 particles facilitate degradation. Another strategy involves the TiO2 over support materials with high specific surface area, such as activated carbon, zeolite, silica, and. In the present study, OMS-2 was employed to modify the CN-TiO2, enhance its photocatalytic activity in methyl orange dye degradation under the daylight irradiation and the probable photocatalytic mechanism under daylight irradiation was proposed

Results and Discussion

Photocatalytic Mechanism

Chemicals

Photocatalytic Evaluation with Methyl orange under Daylight

Conclusions