Quantum Calculations of Hydrogen Absorption and Diffusivity in Bulk CeO₂

Area of Science:

• Materials Science
• Computational Chemistry
• Physical Chemistry

Background:

• Cerium dioxide (CeO2) is crucial for heterogeneous catalysis involving hydrogen.
• Understanding CeO2 bulk properties and hydrogen interactions is limited by scarce experimental data and varied computational results.

Purpose of the Study:

• To investigate hydrogen interactions within bulk stoichiometric CeO2 using various DFT methods.
• To establish reliable computational bounds for key physical-chemical properties of CeO2 relevant to hydrogen.

Main Methods:

• Density Functional Theory (DFT) calculations.
• Utilized generalized gradient (GGA), metaGGA, and hybrid functionals.
• Incorporated corrections for electronic correlations.

Main Results:

• Established reasonable DFT-derived bounds for lattice constants, band gaps, hydrogen absorption energies, and O-H vibrational frequencies.
• Calculated uniformly low activation energy barriers (<0.15 eV) for hydrogen bulk diffusion.
• Determined that hydrogen tunneling effects are minimal at ambient temperatures.

Conclusions:

• The study provides a systematic approach for determining fundamental Ce-O-H interaction properties.
• Offers realistic ranges for hydrogen diffusion kinetics in CeO2.
• Facilitates the development of coarse-grained models to guide experimental research.