Insight into the role of copper in the promoted photocatalytic removal of NO using Zn2-xCuxCr-CO3 layered double hydroxide

In this work the ability of Zn2-xCuxCr-CO3 layered double hydroxides (LDHs) as highly efficient DeNOx photocatalysts was studied. LDHs with x = 0, 0.2 and 0.4 were prepared using a coprecipitation method. The samples were characterized by different techniques such as XRD, XPS, FT-IR, ICP-MS, TG, SBET, SEM and Diffuse reflectance (DR). The increased amount of copper ions in the LDH layers gave rise to slight changes in the structure and morphology and an important variation of the optical properties of the LDHs. The prepared ZnCuCr–CO3 photocatalysts exhibited favourable conversion efficiency (51%) and an extraordinary selectivity (97%) for the photochemical NO abatement. The photochemical mechanism was elucidated from DOS, EPR, Femtosecond transient absorption and in-situ DRIFTS studies. The results suggested that the presence of Cu2+ ions in the LDH framework introduced new states in the valence band states, thus favouring the production and mobility of e−/h+ charge carriers and a greater production of ⋅O2− and ⋅OH. [Display omitted] •Zn2-xCu2Cr LHDs are effective UV–Vis light DeNOx photocatalysts.•The Zn2+ by Cu2+ ion replacement increases the surface area and light absorption.•The Cu centres create new states in the valence band.•The production of ROS species is favoured in doped samples.