  Nanostars (NSTs) are spiky nanocrystals with plasmonic hot spots. In this
study, we show that strong electromagnetic fields localized in the nanostar
tips are able to generate large numbers of energetic (hot) electrons, which can
be used for photochemistry. To compute plasmonic nanocrystals with complex
shapes, we develop a quantum approach based on the effect of surface generation
of hot electrons. We then apply this approach to nanostars, nanorods and
nanospheres. We found that that the plasmonic nanostars with multiple hot spots
have the best characteristics for optical generation of hot electrons compared
to the cases of nanorods and nanospheres. Generation of hot electrons is a
quantum effect and appears due to the optical transitions near the surfaces of
nanocrystals. The quantum properties of nanocrystals are strongly size- and
material-dependent. In particular, the silver nanocrystals significantly
overcome the case of gold for the quantum rates of hot-electron generation.
Another important factor is the size of a nanocrystal. Small nanocrystals are
more efficient for the hot-electron generation since they exhibit stronger
quantum surface effects. The results of this study can useful for designing
novel material systems for solar photocatalytic applications.
