How Strain Affects the Reactivity of Surface Metal Oxide Catalysts

Abstract

Highly dispersed molybdenum oxide supported on mesoporous silica SBA-15 has been prepared by anion exchange resulting in a series of catalysts with changing Mo densities (0.2-2.5 Mo atoms nm(-2) ). X-ray absorption, UV/Vis, Raman, and IR spectroscopy indicate that doubly anchored tetrahedral dioxo MoO4 units are the major surface species at all loadings. Higher reducibility at loadings close to the monolayer measured by temperature-programmed reduction and a steep increase in the catalytic activity observed in metathesis of propene and oxidative dehydrogenation of propane at 8 % of Mo loading are attributed to frustration of Mo oxide surface species and lateral interactions. Based on DFT calculations, NEXAFS spectra at the O-K-edge at high Mo loadings are explained by distorted MoO4 complexes. Limited availability of anchor silanol groups at high loadings forces the MoO4 groups to form more strained configurations. The occurrence of strain is linked to the increase in reactivity.

Direct Imaging of Octahedral Distortion in a Complex Molybdenum Vanadium Mixed Oxide

“…[16] Fully oxidized polyhedra consisting of Mo or V are known to always show a high out-of-center distortion tendency towards various directions [8,10] due to their ability to form stable "molybdenyl" or "vanadyl" (M=O; M=Mo,V) species. Structurally, the M1 phase represents a group of nonstoichiometric oxides such as Mo 5 [17] Mo 8 O 23 for instance also exhibits a complex framework, composed of distorted edge shared octahedra hosting Mo=O species and less distorted bands of corner shared polyhedra.…”

Modulierung der elektronischen Strukturen anorganischer Nanomaterialien für eine effiziente elektrokatalytische Wasserspaltung

“…[102,103] Das Legieren von Pt mit Seltenerdelementen oder frühen Übergangsmetallen ist eine weitere effektive Strategie,u md ie ORR-Leistungsfähigkeit zu erhçhen. [123][124][125] FürT MOs wurde festgestellt, dass einige von ihnen die Bandzentrum-Theorie befolgen. Wied ie d-Bandzentrum-Theorie vorausgesagt hat, ergab sich eine vulkanfçrmige Beziehung zwischen der d-Bandzentrums-Energie und der spezifischen Aktivität.…”

“…Wied ie d-Bandzentrum-Theorie vorausgesagt hat, ergab sich eine vulkanfçrmige Beziehung zwischen der d-Bandzentrums-Energie und der spezifischen Aktivität. [124] Oft wurden TMDs mit spezieller 2D-Struktur als typische Beispiele gewählt, um die Beziehung zwischen inhärenter Spannung und elektronischer Struktur zu untersuchen. [123][124][125] FürT MOs wurde festgestellt, dass einige von ihnen die Bandzentrum-Theorie befolgen.…”

Strain Engineering to Modify the Electrochemistry of Energy Storage Electrodes

“…Unlike bulk materials, many nanostructures exhibit sizes where strain can homogenously propagate throughout the whole material, instead of only on a surface or an interface6891011121314. In this spirit, recent efforts have demonstrated the capability of strain in nanostructures to modify the energy landscape of catalytic and electro-catalytic surface-bound reactions1516171819 and modify oxygen ion diffusion in fuel cell technology202122. The direct controlled correlation between mechanical strain as an input parameter and electrochemical processes in nanostructures for energy harvesting applications has only very recently been reported23.…”