Elsevier

Catalysis Communications

Volume 66, 5 June 2015, Pages 42-45
Catalysis Communications

Short communication
An efficient Ce-doped MoO3 catalyst and its photo-thermal catalytic synergetic degradation performance for dye pollutant

https://doi.org/10.1016/j.catcom.2015.03.017Get rights and content

Highlights

  • Ce is successfully doped into MoO3.

  • MB dye can be efficiently degraded by Ce(5)/MoO3 while at light-on.

  • MB dye can also be efficiently degraded by Ce(5)/MoO3 while at light-off.

  • A photo-thermal catalytic synergetic effect plays a key role in this reaction.

Abstract

Herein, an efficient Ce-doped MoO3 catalyst is prepared by an impregnation method. Under visible light irradiation (≥ 420 nm) or light-off, Ce(5)-doped MoO3 shows a degradation activity of methylene blue (MB) dye 10 times higher than MoO3 due to the doped Ce. It is proposed that the light-off degradation is predominated by a Mo/Ce redox cycle, instead of a photocatalytic reaction; while the light-on degradation is via a synergetic effect of both photocatalytic oxidation and Mo/Ce redox cycle. This study offers a new concept for environmental cleaning from cost-saving and energy-saving viewpoints.

Introduction

In the past decades, the photo degradation technology of organic compounds has gained widespread attention [1], [2], [3], [4], [5]. Regrettably, its practical application is limited by a low utilization efficiency of solar energy and a low quantum efficiency [6], [7], [8], [9], [10], [11]. Cerium and molybdenum oxides are widely applied in various fields due to their unique physicochemical properties. Ceria is often employed as an oxygen storage and release (OSR) reservoir, due to the facile mutual transformation of Ce4 +/Ce3 + [12], [13], [14]. For example, N. Aman et al. [15] have reported cerium-doped titania at the cerium concentration from 0 to 10 wt.%. Their results show that anatase crystallinity mostly decides the photocatalytic activity rather than only surface area; and the optimum visible light absorption and oxygen vacancy with 5% cerium doping enhances the photocatalytic activity. They hold that photocatalytic performance is found to depend on the presence of Ce4 +/Ce3 + rather than only visible light absorption. Herein, MoO3 and Ce-doped MoO3 were prepared by the hydrothermal and impregnation–calcination methods, respectively. Ce-doped MoO3 as a visible light photocatalyst is used to degrade dyes molecules. It is unexpectedly found that the organic dyes can also be efficiently degraded while light-off under ambient condition, during which a redox cycle of between Mo(VI)/Mo(V) and Ce(IV)/Ce(III) plays a key role. The experimental details are provided in Electronic Supporting Information (ESI).

Section snippets

Results and discussion

Figs. S1 and S2 (ESI) confirm the formation of hexagonal MoO3 (h-MoO3) consisting of 4–9 μm long six-prism nanorods. Moreover, the unique hexagonal structure of h-MoO3 is expected to facilitate the doping of foreign ions. After calcination, the nanorods have become irregular particles and the surfaces become rough. The electron diffraction (ED) patterns (Fig. S2c of ESI) reveal the single-crystalline nature of MoO3 and the polycrystalline nature of the doped MoO3 [16], [17]. X-ray diffraction

Conclusion

To conclude, under light-on or light-off condition, Ce(5)/MoO3 catalyst shows a high degradation activity of MB. The former is through the synergetic photocatalytic and redox cycle mechanism; while the latter is predominated by a redox cycle.

Acknowledgments

This work is financially supported by National Science Foundation of China (21377060, 21103049), the Key Project of Environmental Protection Program of Jiangsu (2013016, 2012028), the Project Funded by the Science and Technology Infrastructure Program of Jiangsu (BM2013139, 201380277), Six Talent Climax Foundation of Jiangsu (20100292), Jiangsu Science Foundation of China (BK2012862), Jiangsu Province of Academic Scientific Research Industrialization Projects (JHB2012-10, JH10-17), and “333”

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    Notes: The first and second authors contribute to the work equally.

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