Photocatalytic
and electrocatalytic reactions to produce value-added
chemicals offer promising solutions for addressing the energy crisis
and environmental pollution. Photocatalysis is driven by light excitation
and charge separation and relies on semiconducting catalysts, while
electrocatalysis is driven by external electric current and is mostly
based on metallic catalysts with high electrical conductivity. Due
to the distinct reaction mechanism, the conversion between the two
catalytic types has remained largely unexplored. Herein, by means
of density functional theory (DFT) simulations, we demonstrated that
the ferroelectric heterostructures Mo-BN@In2Se3 and WSe2@In2Se3 can exhibit semiconducting
or metallic features depending on the polarization direction as a
result of the built-in field and electron transfer. Using the nitrogen
reduction reaction (NRR) and hydrogen evolution reaction (HER) as
examples, the metallic heterostructures act as excellent electrocatalysts
for these reactions, while the semiconducting heterostructures serve
as the corresponding photocatalysts with improved optical absorption,
enhanced charge separation, and low Gibbs free energy change. The
findings not only bridge physical phenomena of the electronic phase
transition with chemical reactions but also offer a new and feasible
approach to significantly improve the catalytic efficiency.