Inspired by transformation
optics, we propose a new concept for
plasmonic photocatalysis by creating a novel hybrid nanostructure
with a plasmonic singularity. Our geometry enables broad and strong
spectral light harvesting at the active site of a nearby semiconductor
where the chemical reaction occurs. A proof-of-concept nanostructure
comprising Cu2ZnSnS4(CZTS) and Au–Au
dimer (t-CZTS@Au–Au) is fabricated via a colloidal strategy
combining templating and seeded growth. On the basis of numerical
and experimental results of different related hybrid nanostructures,
we show that both the sharpness of the singular feature and the relative
position to the reactive site play a pivotal role in optimizing photocatalytic
activity. Compared with bare CZTS, the hybrid nanostructure (t-CZTS@Au–Au)
exhibits an enhancement of the photocatalytic hydrogen evolution rate
by up to ∼9 times. The insights gained from this work might
be beneficial for designing efficient composite plasmonic photocatalysts
for diverse photocatalytic reactions.