To gain insight into the mechanism of GNBs formation, we first performed time-lapse TEM imaging and time-resolved UV/VIS/NIR absorption analysis in the GNBs synthesis (Figures and). Figure shows that the rod-like nanomaterial was formed within 1 h, and the wing part of the GNB matured over the subsequent several hours. The UV/VIS/NIR spectral change corresponded to the results of the TEM images (Figure ). Concretely, one strong NIR peak, which was typical of GNR, followed by another relatively weak one in the visible area, emerged. Afterward, both peaks shifted gradually toward the peak location of GNBs within ~10 h. These data indicate that the GNBformation process comprised two steps, namely the rapid formation of the anisotropic shape and the gradual maturing into the butterfly shape.