Figure 4

(a) Zeta potential of exfoliated Nb₂Se₉ in IPA. (b) XPS spectrum for Nb₂Se₉ with octadecylamine showing presence of N 1s peak. (c) XPS spectra of Se 3d peak without and with octadecylamine, showing upward shift of 0.5 eV in binding energy. (d) XPS spectra of Nb 3d peak without and with octadecylamine.