Exploiting phase transitions in catalysis: reaction ofCO2andH2on dopedVO2-polymorphs

Area of Science:

• Materials Science
• Surface Chemistry
• Catalysis

Background:

• Vanadium dioxide (VO2) exhibits reversible phase transitions between tetragonal rutile and monoclinic structures.
• Previous studies show differing CO adsorption energies on Mo-stabilized VO2 polymorphs.
• This difference can be leveraged to enhance catalytic reactions by managing CO surface coverage.

Purpose of the Study:

• Investigate the potential of VO2 phase transitions to influence CO2 hydrogenation thermodynamics and kinetics.
• Demonstrate proof-of-principle for using VO2 polymorphs to tune catalytic reaction pathways.
• Explore the feasibility of a catalytic cycle based on VO2 phase transitions.

Main Methods:

• Density Functional Theory (DFT) calculations for adsorption energies of CO2, intermediates, and products.
• Nudged Elastic Band (NEB) method to calculate reaction barriers for CO2 hydrogenation.
• Distinguished Reaction Coordinate (DRC) method to determine the minimum energy path for VO2 bulk phase transition.

Main Results:

• Significant differences in reaction energies for CO2 hydrogenation to formic acid and formaldehyde were observed between VO2 polymorphs.
• VO2 was found to lower reaction barriers for CO2 hydrogenation compared to the gas phase.
• The minimum energy path for the undoped VO2 bulk phase transition was elucidated.

Conclusions:

• VO2 phase transitions can alter CO2 hydrogenation thermodynamics and kinetics.
• Catalytic reaction conditions can be optimized by stabilizing specific VO2 polymorphs.
• A novel catalytic cycle exploiting the VO2 phase transition is proposed based on theoretical findings.