Engineering an ultrathin amorphous TiO2 layer for boosting the weatherability of TiO2 pigment with high lightening power

• Published in: Chinese journal of chemical engineering Vol. 27; no. 11; pp. 2825 - 2834
• Main Authors: Yu, Yangyang, Wu, Kejing, Lu, Shiyu, Ma, Kui, Zhong, Shan, Zhang, Hegui, Zhu, Yingming, Guo, Jing, Yue, Hairong, Liu, Changjun, Tang, Siyang, Liang, Bin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2019; Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610207, China; Low-Carbon Technology and Chemical Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University, Chengdu 610065, China%Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610207, China%Institute for Clean Energy&Advanced Materials, Faculty of Materials and Energy, Southwest University, Chongqing 400715, China%Shanxi Province Key Laboratory of Higee-Oriented Chemical Engineering, North University of China, Taiyuan 030051, China%Low-Carbon Technology and Chemical Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University, Chengdu 610065, China
• Subjects: Lightening power; Photocatalytic suppression mechanism; Pulsed chemical vapor deposition; TiO2 pigments; Ultrathin layer; Weatherability; Lightening power; Weatherability; Ultrathin layer; Pulsed chemical vapor deposition; TiO2 pigments; Photocatalytic suppression mechanism
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/j.cjche.2019.04.002

TiO2 pigments are typically coated with inert layers to suppress the photocatalytic activity and improve the weatherability. However, the traditional inert layers have a lower refractive index compared to TiO2, and therefore reduce the lightening power of TiO2. In the present work, a uniform, amorphous, 2.9-nm-thick TiO2 protective layer was deposited onto the surface of anatase TiO2 pigments according to pulsed chemical vapor deposition at room temperature, with TiCl4 as titanium precursor. Amorphous TiO2 coating layers exhibited poor photocatalytic activity, leading to a boosted weatherability. Similarly, this coating method is also effective for TiO2 coating with amorphous SiO2 and SnO2 layers. However, the lightening power of amorphous TiO2 layer is higher than those of amorphous SiO2 and SnO2 layers. According to the measurements of photoluminescence lifetime, surface photocurrent density, charge-transfer resistance, and electron spin resonance spectroscopy, it is revealed that the amorphous layer can prevent the migration of photogenerated electrons and holes onto the surface, decreasing the densities of surface electron and hole, and thereby suppress the photocatalytic activity.
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