Cr~(3+) substituted Zn-Al layered double hydroxides as UV-Vis light photocatalysts for NO gas removal from the urban environment

摘要

The ZnAl-CO_3, ZnAlCr-CO_3 and ZnCr-CO_3 LDH samples were studied as De-NOx photocatalysts in this work. Samples without Cr and increasing the presence of Cr~(3+) in the LDH framework in the 0.06,0.15 and 0.3 Cr/Zn ratio were prepared by co-precipitation method, all of them constituted by pure LDH phase. The increase of chromium content in the LDH framework leads to lower crystallinity and higher specific surface area in the samples. Moreover, the CrO_6 octahedron centres expand the photo-activity from UV to Visible light and assist to decrease the recombination rate of the electrons and holes. The favourable textural, optical and electronic properties of Cr-containing LDH samples explain the good NO removal efficiency (55%) and outstanding selectivity (90%) found for the analysed De-NOx process.