Hence, the intercalation of cations causes a hindrance to the water transport in the nanochannels (Figure ). This hindrance increases exponentially with the hydrated diameter of intercalated cations, as shown in Figure . This shows that enhanced interaction between water molecules and cation decorated graphitic nanochannel is responsible for the decrease in water flux. The fact that the hydrated diameter of H + fits the exponential function indicates that hydrated hydrogen ions may govern the water transport in the original GOM (Figure ).