Molybdenum Oxide Constructed by {Mo₆O₂₁}^6– Pentagonal Unit Assembly and Its Redox Properties

Abstract

Molybdenum oxides are widely used in various fields due to their electronic and structural characteristics. These materials can generate lattice oxygen defects by reduction treatments, which sometimes play central roles in various applications. However, little has been understood about their properties since it is difficult to increase the amount of lattice oxygen defects due to the crystal structure changes in most cases. Here, we report a new class of high-dimensionally structured Mo oxide (HDS-MoO x ) constructed by the random assembly of {Mo 6 O 21 } 6− pentagonal units (PUs). Since the PU is a stable structural unit, the structural network based on the PU hardly caused structural changes to make the lattice oxygen defects vanish. Consequently, HDS-MoO x could generate a substantial amount of lattice oxygen defects, and their amount was controllable, at least in the range of MoO 2.64 −MoO 3.00 . HDS-MoO x was more redox active than typical Mo oxide (α-MoO 3 ) and demonstrated an oxidation ability for gas-phase isopropanol oxidation under the reaction conditions, whereas α-MoO 3 affords no oxidation products.