Probing local structure of paramagnetic Ni-Al layered double hydroxides with solid-state 2H NMR spectroscopy

H-2 MAS NMR spectroscopy was applied to investigate the local structure of deuterated paramagnetic Ni2+-containing layered double hydroxides (LDHs) for the first time. Due to significantly smaller electronic dipole interaction, H-2 NMR spectra of NiAl-LDHs show much better resolution than H-1 NMR spectra, and different hydrogen species, including Ni3OD, Ni2AlOD and interlayer water, can be resolved in H-2 NMR spectra. Quantitative analysis of the NMR spectra of LDHs with different Al percentages confirms the ordering of Al3+ ions in the hydroxide sheets (Al-O-Al avoidance). H-2 MAS NMR spectroscopy gives new insight into different hydrogen species in paramagnetic NiAl-LDH and this approach can be extended to study the detailed structural information and properties of other paramagnetic LDHs. (C) 2018 Elsevier B.V. All rights reserved.