The impact of residual adsorbate on the characterization of microporous carbons with small angle scattering

Microporous carbon materials were investigated with small angle X-ray scattering to determine whether a pre-treatment with heat and vacuum of the samples is necessarily required to obtain accurate and reliable data. The findings of this study indicate strongly erroneous data in terms of micropore volume and apparent sample density, if the samples are not carefully degassed prior to the measurement, even when the measurement is performed in high vacuum. The observed scattering curves were compared to a systematically wetted sample. The results further show an ageing of the samples that causes predominant cluster adsorption most likely of water at oxygen surface groups. Some recommendations are given for an adequate sample preparation prior to characterizing (micro)porous materials with small angle scattering.