  Electrocatalysis is a catalytic process where the rate of an electrochemical
reaction occurring at the electrode-electrolyte interface can be controlled by
varying the electrical potential. Electrocatalysis can be applied to generate
hydrogen which can be stored for future use in fuel cells for clean
electricity. The use of solid oxide in electrocatalysis specially in hydrogen
evolution reaction is promising. However, further improvements are essential in
order to meet the ever-increasing global energy demand. Improvement of the
performance of these high energy chemical systems is directly linked to the
understanding and improving the complex physical and chemical phenomena and
exchanges that take place at their different interfaces. To enable large length
and time scale atomistic simulations of solid oxide electrocatalysis for
hydrogen generation, we developed an eReaxFF force field for barium zirconate
doped with 20 mol% of yttrium (BZY20). All parameters for the eReaxFF were
optimized to reproduce quantum mechanical (QM) calculations on relevant
condensed phase and cluster systems describing oxygen vacancies, vacancy
migrations, water adsorption, water splitting and hydrogen generation on the
surfaces of the BZY20 solid oxide. Using the developed force field, we
performed zero-voltage molecular dynamics simulations to observe water
adsorption and the eventual hydrogen production. Based on our simulation
results, we conclude that this force field sets a stage for the introduction of
explicit electron concept in order to simulate electron conductivity, electron
leakage and non-zero-voltage effects on hydrogen generation. Overall, we
demonstrate how atomistic-scale simulations can enhance our understanding of
processes at interfaces in solid oxide materials.
