NAP-XPS Probes the Electronic Structure of the Mg–Al–Cl Layered Double Hydroxide upon Controlled Hydration
Romain Coustel, Anthony Boucly, Erwan André, Arnaud Di Bitetto, Fabrice Bournel, Jean‐Jacques Gallet, F. Rochet, Cédric Carteret
Abstract
The hydration of [Mg 2 Al(OH) 6 ] + [Cl –, y H 2 O] LDH was investigated by volumetric water adsorption, X-ray diffraction, Fourier Transformed Infrared (FTIR) sepctroscopy, and Near Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS). It was demonstrated that water uptake into interlayer region can be quantified by NAP-XPS. The LDH’s electronic structure is assessed for increasing relative humidity ( RH ) up to 0.044. The Cl 2p level appears essentially unaffected by water uptake, but as supported by DFT calculation, H-bonds between chloride and water induce Cl 3p orbitals splitting. At RH = 0.7, LDH is covered by a water film that contains Mg and Cl species but no Al. Soft X-ray radiolysis of hydrated Cl species induces the formation of oxidized Cl species.