The interaction between the pillaring alkyldiamine molecules and the V2O5 host is analyzed by X-ray photoelectron spectroscopy (XPS). Both the O 1s and V 2p signals of all alkyldiaminepillared samples are shown in Fig. . Two signals corresponding to the spin-orbit of V 2p3/2 and V 2p1/2 are located in the energy ranges around 517 and 525 eV, respectively, which contain contributions of V(V) and V(IV). This shows that surface vanadium in the alkyldiamine-pillared V2O5 samples is partially reduced after the chemical synthesis. The N 1s signals (Fig. ) show the main signal centered at 401.5 eV for V2O5-2C-DA, 401.2 eV for V2O5-6C-DA, and 401.8 eV for V2O5-12C-DA, which can be assigned to a positively charged nitrogen, such as -NH3 + . Hence, most pillar functional groups form cationic ammonium groups in the aqueous reaction solution, which interact by ionic bonding with the V2O5 host.