In addition to the changes in the electronic properties of hexagonal tungsten oxide with electrochemical reduction, we monitored structural changes using Raman spectroscopy (Figure ). The pristine NCs prior to any electrochemical reduction show multiple Raman modes between 50-150 cm -1 , 200-350 cm -1 , 650-800 cm -1 , and 850-1000 cm -1 . These modes correspond to lattice modes, δ(O-W-O), ν(O-W-O), and ν(W=O), respectively. The most prominent differences between the reduced and pristine films occur in the ν(O-W-O) modes located between 650-800 cm -1 . For the Li + intercalated film, there are significant changes to the peaks corresponding to this mode, with the two peak structure present in the pristine sample merging into one broad peak. The blue shift of the lower frequency peak and red shift of the higher frequency peak is consistent with changes in the lattice parameters during the intercalation of cations, with the c-axis shortening and the a-axis lengthening. The two peak structure has been assigned as ν(O-W-O) modes in the two crystallographic directions, with the lower frequency peak corresponding to the c-axis. The merging of these two peaks is most easily seen in the Li + intercalated film, but similar shifts are shown for the Na + intercalated film. In the K + intercalated film, the two peaks remain, both shifting to higher frequency, though the lower frequency peak shifts much more significantly than the higher frequency one. The reduction of the material in a TBA + electrolyte does not significantly impact the two-peak structure in this region, which is consistent with our interpretation that this structural change is the result of lattice distortions due to cation intercalation.