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doi: 10.1007/s40242-020-0303-z

Article

Transparent Coating with TiO 2 Nanorods for High-performance Photocatalytic Self-cleaning and Environmental Remediation JIANG Wenshuai, ZONG Xupeng *, WANG Xiayan and SUN Zaicheng* Center of Excellence for Environmental Safety and Biological Effects, Beijing Key Laboratory for Green Catalysis and Separation, Department of Chemistry and Biology, Beijing University of Technology, Beijing 100124, P. R. China Abstract High-performance self-cleaning coatings are highly desired by the industry and market. Herein, we synthesized two kinds of ultrafine TiO2 nanocrystals, one is anatase dots with a diameter of 5 nm, and the other is rutile rods with 1.5 nm in width and 7 nm in length. The prepared TiO2 nanocrystal is highly dispersed and stable in water over a month. The coating can be fabricated via a simple spraying method, displaying excellent optical properties and photocatalytic performance on self-cleaning and surrounding environment remediation. The transmittance of glass remains 80%—90% for visible and near-infrared light after 30 cycles of spray. RhB solution(50 mg/L) was applied to the coating surface and form a solid RhB layer was formed, which can be completely removed in 30 min’s light irradiation. RhB aqueous solution(100 mL, 5 mg/L) was purified after 180 min by a 10 cm×10 cm glass, on which the coating was sprayed 30 times. The concentrations of formaldehyde and PM 2.5 in surrounding air displayed a significant decrease along 50 min’s monitoring. This high-performance coating shows great potential for constructing functional coating on various substrates for industrial applications. Keywords TiO2; Photocatalysis; Transparent coating; Self-cleaning; Environment remediation

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Introduction

Self-cleaning coating with high-performance is highly desired commercially for its wide applications on different substrates from outer walls, interior finishes, vehicle surfaces, textiles, window glasses to solar devices[1—5]. Coatings with semiconductors could chemically break down dirt and other impurities under sunlight irradiation[3,6—8]. On the surface of the involved semiconductor, the light-induced holes and superoxide radicals formed from atmospheric oxygen with photogenerated electrons oxidize the adsorbed organic molecules into carbon dioxide and water[9,10]. A large number of pollutants including aromatics, dyes, non-degradable polymers, toxic gas even PM2.5 can be eliminated using this technology, resulting in the cleaning of the surface and the remediation of the environment[11,12]. This environmentally friendly technology has received a great deal of attention from the industry for it is labor-saving and free from maintenance cost. Although several commercial products for glazing have already available in the market, the fabrication of coating is still to be developed to meet higher optical

requirements. One main concern for the coating used for glazing or painting is that the coating layer should be highly transparent without changing the transmittance or original c