Cr3+ substituted Zn-Al layered double hydroxides as UV–Vis light photocatalysts for NO gas removal from the urban environment

• Published in: The Science of the total environment 2020-03, Vol.706, p.136009, Article 136009
• Main Authors: Rodriguez-Rivas, Fredy, Pastor, Adrián, de Miguel, Gustavo, Cruz-Yusta, Manuel, Pavlovic, Ivana, Sánchez, Luis
• Format: Article
• Language: English
• Subjects: Chromium; LDH; Photocatalyst; Zinc
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.136009

The ZnAl-CO3, ZnAlCr-CO3 and ZnCr-CO3 LDH samples were studied as De-NOx photocatalysts in this work. Samples without Cr and increasing the presence of Cr3+ 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 CrO6 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. [Display omitted] •ZnAlCr-CO3 LHDs are effective UV–Vis light De-NOX photocatalysts.•The Al3+ by Cr3+ ion replacement increases the surface area and Vis light absorption.•The Cr centres decrease the e−/h+ recombination enhancing the ROS species production.•The observed De-NOX performance is remarkable for urban environments.