Oriented structures of alcohol hidden in carbon micropores with ERDF analysis

The X-ray diffraction (XRD) of alcohol molecules such as methanol, ethanol, and 1-propanol confined in slit-shaped graphitic micropores of activated carbon fibers (ACFs) having different pore widths was measured at 303 K. The effect of the pore width on the molecular assembly structure of alcohol in the micropores was examined. The XRD patterns were analyzed by use of the electron radial distribution function (ERDF) analysis. The adsorbed density of alcohol in micropores of 1.1 nm in width was close to the solid density, while that in micropores of 0.7 nm in width was smaller than the liquid density. The ERDF of alcohol adsorbed in the 0.7 nm micropores showed a highly ordered structure compared with the 1.1 nm micropores, which is completely different from the adsorbed density results. It was presumed that alcohol molecules are hydrogen-bonded to form a layered structure, which is fit for the slit-shaped micropore.