Charge Redistribution in Mechanochemical Reactions for Solid Interfaces

Mechanochemical
strategies are widely used in various fields, ranging
from friction and wear to mechanosynthesis, yet how the mechanical
stress activates the chemical reactions at the electronic level is
still open. We used first-principles density functional theory to
study the rule of the stress-modified electronic states in transmitting
mechanical energy to trigger chemical responses for different mechanochemical
systems. The electron density redistribution among initial, transition,
and final configurations is defined to correlate the energy evolution
during reactions. We found that stress-induced changes in electron
density redistribution are linearly related to activation energy and
reaction energy, indicating the transition from mechanical work to
chemical reactivity. The correlation coefficient is defined as the
term “interface reactivity coefficient” to evaluate
the susceptibility of chemical reactivity to mechanical action for
material interfaces. The study may shed light on the electronic mechanism
of the mechanochemical reactions behind the fundamental model as well
as the mechanochemical phenomena.