Zn-Al layered double hydroxides as efficient photocatalysts for NOx abatement
Sánchez Granados, Luis
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In this study,we report that layered double hydroxides (LDH) exhibited high photocatalytic activitiesin degrading NOx gases for the first time. ZnAl-CO3LDHs with a 1.5 to 3.0 Zn/Al ratio were prepared by a coprecipitation method both with and without hydrothermal treatment.Syntheses were carried out with high and low metal concentrations, the latter being the most favorablein obtaining pure LDHs in the whole Zn/Al ratio range. The samples were characterized by different techniques suchas PXRD, FT-IR, ICP mass, TGA, SBET, SEM and Diffuse reflectance (DR). The LDH particlesgrew as well-defined hexagonal nanolayers, whosesize and crystallization dependedon the synthetic procedure and the Zn/Al ratio. Those samples with lower crystallinity exhibit the highest specific surface area values (> 50 m2·g-1). The ZnAl-CO3LDHs were UV light responsive with band–gap valuescloseto 3.5 eV. The LDH photocatalysts show a high performance towards the photochemical oxidation process of NO gas, withefficiencies of around 55 %. Remarkably, the ZnAl-CO3photocatalysts exhibit an impressive selectivity towards the deNOx process, avoiding the emission of the toxic NO2gas into the atmosphere. Interestingly,these promising deNOx results are repeated when working for a long irradiation period or with the highest concentration of NO in polluted atmospheres.
Embargado hasta 02-05-2020