Fusion TEM holder tip
Image courtesy of Top. Catal.

Abstract

A Mo–V–Nb–Te–O oxidation catalyst has been imaged using scanning transmission electron microscopy at 780 K, which is slightly above its operating temperature. We observe a sublattice disordering of the corner-sharing octahedra forming the catalytic sites containing V5+ while the edge-sharing pentagonal bipyramidal {Nb(Mo5)} sublattice remains structurally more rigid and thereby maintains the overall structural integrity of the catalyst. Imaging the termination of the edges of the [001] basal zones at room temperature reveal a preference for presence of a closed network of secondary structural {Nb(Mo)5} units providing further evidence of the stability of this sublattice structure. We propose that sublattice disordering of catalytic sites enables structural flexibility to accommodate different oxidation states during multistep chemical reactions within a more rigid superstructure and presents a new paradigm for compositionally and structurally complex catalysts.

Impact Statement

The imaging of a Mo-V-Nb-Te-O oxidation catalyst with STEM at 780 K, slightly above its operating temperature. The researchers observed the sublattice disordering of cornersharing octahedra forming catalytic sites containing catalytic sites containing V5+, and they proposed that sublattice disordering of catalytic sites allows them to adapt to various oxidation states while remaining within a more solid superstructure.