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RESEARCH PRODUCT

Atomic Layer Deposition of Au-TiO2 inverse opals for the visible light photocatalysis of dyesdegradation

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The pollution of waste water due to organic dyes used in the textile and chemical industries is an important environmental issue. Inverse opals (IO) offer a great potential for increasing the efficiency of their degradation by semiconductor photocatalysts such as TiO2 by the synergy of high specific surface and photonic crystal properties [1]. Doping TiO2 with gold nanoparticles is another possible strategy to enhance its photocatalytic activity by increasing its optical absorption in the visible range [2].This work reports the synthesis of Au-TiO 2 IO films by Atomic Layer Deposition and the study of their visible-light photocatalytic activity for the degradation of methylene blue in water solution compared to pure TiO2 IO and flat Au-TiO2 films. The use of preformed nanoparticles with a narrow size distribution allows to better control their plasmonic properties including light absorption in the visible range. The morphology of Au-TiO 2 IO films and the distribution of Au nanoparticles have been analyzed by scanning electron microscopy (Fig. 1) and nano-SIMS. Their composition and structure have been investigated by XPS and Raman spectroscopy.The degradation kinetics of methylene blue was studied using Au-TiO2 IO films as visible light photocatalysts. Flat Au-TiO2 films were also used for comparison.It has been shown that doping of TiO 2 with gold nanoparticles allows to obtain a faster degradation which reaches about 95 % in 7 hours instead of 90 % after 14 hours with flat films. These results highlight the potential of Au-TiO2 inverse opal films synthesized by ALD for visible lightphotocatalytic applications.[1] L. Hu et al., Catalysis Communications 40 (2013) 106 – 110.[2] S. W. Verbruggen, J. Photochem. and Photobiology C: Photochem. Reviews 24 (2015) 64 - 82.