The Electronic Structure or Charge Delocalization of Sulfated Zirconia (Supported on Multi-walled Carbon Nanotubes): Acid Sites Probed by X-ray Absorption Spectroscopy.

X-ray absorption of inter-atom transitions (Zr L-, O K- and S K-edges) were used to probe the interaction of sulfate with nanoparticles of ZrO supported on multi-walled carbon nanotubes with the goal of describing the electronic interaction of formation of acid sites on sulfated zirconia. The changes in intensity at the Zr-O-S interface are first interpreted as charge transfer within various molecular orbitals using spectra of all three elements (Zr L-, O K- and S K-edges). An alternative interpretation of intensity, particularly for the sulfate precursor, is made in terms of charge distribution over molecular orbitals of different size and shape that result from the sulfate precursor decomposition and/or interaction with zirconia. Graphical Abstract: Zr L-edge XANES of S-ZrO/MWCNT annealed at different temperatures (250 °C ~ 550 °C), showing interaction between Zr and S.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]