Layered double hydroxides reconstructed in NiSO4 aqueous solution as highly efficient photocatalysts for degrading two industrial dyes

Nanostructured photocatalysts, that can effectively photodegrade the industrial dyes drimaren red and drimaren navy (Clariant Produkte), were obtained by the structural reconstruction of MgAlLDH and MgFeAlLDH anionic clays in NiSO4 aqueous solution. X-ray diffraction (XRD), energy dispersive X-ray (EDX) mapping, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), N2 adsorption at 77 K and UV–vis analysis were adopted to investigate the structure, surface, micromorphology and photoresponsive properties of the reconstructed clays, as oposed to the as-synthesized clays. Results show that MgAlLDH and MgFeAlLDH reconstruction in NiSO4 aqueous solution gives rise to nanostructured enssembles defined by high density nanoparticles of oxidized nickel deposited on the larger LDHs flakes. IR spectroscopy (FTIR) results indicate that SO42− replaced CO32− in the interlayer space of the reconstructed clays. It was found that the dyes’ photodegradation is greatly enhanced by the deposition of nanosized nickel on the surface of the clay but is also influenced by the specific composition of the parent clay.