The role of O2 was also studied as it plays an important role
during the photochemical approach described by Mirkin’s group.
It was found that the nanoprisms could be obtained even in the
solution degassed by N2 (see Supporting Information Figure S6).
In the photochemical approach, O2 is necessary to oxidatively
dissolve some Ag nanoparticles and generate Ag+, leading to a
Ag+/Ag nanoparticles copresence environment and thus the
growth of the nanoprisms.26 It is reasonable that O2 is not
necessary in such stepwise reduction approach since there was
suitable amount of residual Ag+ during the growth of the
nanoprisms.