Oxygen-Atom Defect Formation in Polyoxovanadate Clusters via Proton-Coupled Electron Transfer

Area of Science:

• Materials Science
• Surface Chemistry
• Catalysis

Background:

• Hydrogen atom (H-atom) uptake in reducible metal oxides is crucial for catalysis and energy storage.
• Understanding the atomic-level physicochemical factors governing H-atom uptake is challenging without computational modeling.

Purpose of the Study:

• To elucidate the mechanism of oxygen-atom vacancy formation in hexavanadate assemblies.
• To present a novel pathway for defect site formation on redox-active metal oxide surfaces.
• To provide atomistic insights into proton-coupled electron transfer (PCET) at the nanoscale.

Main Methods:

• Kinetic investigations of H-atom transfer to hexavanadate assemblies.
• Analysis of transient V^III-OH₂ moieties and polyoxovanadate-alkoxide cluster formation.
• Correlation of oxidation state distribution with surface oxido ligand affinity for H-atoms.

Main Results:

• A novel pathway for oxygen-atom vacancy formation via proton-coupled electron transfer (PCET) was identified.
• Concerted proton-electron transfer leads to transient V^III-OH₂ formation, followed by water ligand displacement.
• The oxidation state distribution within the cluster core governs H-atom affinity, mimicking reducible metal oxide nanocrystals.

Conclusions:

• This study reveals a new mechanism for defect site formation on metal oxide surfaces.
• The findings offer design criteria for predicting PCET reactivity of terminal M═O moieties.
• Understanding these surface processes is key for advancing catalysis and energy storage applications.