Probing the structural and electronic properties of small vanadium monoxide clusters

Area of Science:

• Materials Science
• Computational Chemistry
• Surface Science

Background:

• Understanding the structural evolution and bonding in early transition-metal oxide clusters is crucial for catalysis and materials design.
• Vanadium oxide clusters (VnOq) are of particular interest due to their variable oxidation states and catalytic activity.

Purpose of the Study:

• To investigate the structural evolution and bonding of vanadium monoxide clusters (VnOq, n=3-9, q=0,-1).
• To determine the ground states of these clusters and resolve energetically similar isomers.
• To assess the oxygen adsorption capabilities of vanadium oxide clusters.

Main Methods:

• Employed photoelectron spectroscopy (PES) for experimental measurements.
• Utilized density functional theory (DFT) calculations, including the Saunders 'Kick' global minimum search, to generate and analyze cluster isomers.
• Compared theoretical electron detachment energies with experimental data to validate ground state assignments.

Main Results:

• Successfully determined the electronic and atomic structures of size-selected vanadium monoxide clusters.
• Identified a pronounced even-odd alternation phenomenon in second difference and adsorption energies as a function of cluster size.
• Observed surprisingly high adsorption energies for oxygen atoms on both anionic and neutral vanadium clusters, indicating strong O activation potential.

Conclusions:

• The synergy between PES and DFT calculations is highly effective for characterizing complex cluster systems and distinguishing between close isomers.
• Vanadium oxide clusters exhibit unique structural and bonding properties with significant implications for oxygen activation.
• The findings suggest that structural defects in vanadium oxides play a key role in their catalytic capabilities.