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5931670 
Journal Article 
Ammonium-treated birnessite-type MnO2 to increase oxygen vacancies and surface acidity for stably decomposing ozone in humid condition 
Cao, R; Zhang, P; Liu, Y; Zheng, X 
2019 
Yes 
Applied Surface Science
ISSN: 0169-4332 
Elsevier 
AMSTERDAM 
495 
English 
WOS:000486177700067 
Nowadays atmospheric ozone pollution increasingly occurs in summer in China developed areas. To improve catalytic stability of MnO2 for decomposing ozone in real humid environment, we developed a simple method to obtain the ammonium (NH4+) treated birnessite-type MnO2 (N-MnO2). NH4+ ions not only replaced K+ ions in the interlayer of MnO2 but also existed on the surface of MnO2, separating the original aggregated MnO2 nanoparticles into smaller ones. The N-MnO2 had much larger specific surface area than the original MnO2 (221 m(2)/g vs. 59 m(2)/g), leading to more oxygen vacancies and enhanced surface acidity. As a result, N-MnO2 exhibited excellent and stable activity for ozone decomposition in humid condition (relative humidity 50%) at room temperature, achieving 80% conversion of 115 ppm ozone under the space velocity as high as 600 L/g ca ch. In addition, N-MnO2 powder was successfully coated on the non-woven fabric. This composite material not only showed stable 60-80% conversion of 15 ppm ozone in a 7-day test, but also its air pressure-drop was only 3 Pa under the commonly used air filtration face velocity of 5.3 cm/s. Thus, as-synthesized N-MnO2 showed great potential in real building ventilation system to prevent ozone pollution from outdoor air. 
Ammonium treating; MnO2; Oxygen vacancy; Surface acidity; Ozone decomposition 
APPLIED SURFACE SCIENCE