Investigation of a Few Noble Metal Oxides with ¹⁷O Solid-State NMR Spectroscopy

Noble metal oxides are highly valuable and act as a key component of metal-oxide interfaces in oxide-supported noble metal catalysts, which play a crucial role in modern industrial society. Here, we investigate the structure of four common and stable noble metal oxides using ¹⁷O solid-state NMR. The optimal isotopic labeling temperature ensures the highest labeling efficiency while preserving the structure of the oxides. The variation in characteristic signals for each noble metal oxide reveals oxygen species in different chemical environments, while the NMR parameters related to chemical shift anisotropy and quadrupolar interaction obtained from spectral fitting indicate more structural information. DFT calculations are used to assist spectral assignments for various oxygen species. This work serves as a prerequisite for studying solid-state NMR of oxide-supported noble metal catalysts.