  Nonspecific molecular adsorption like airborne contamination occurs on most
surfaces including those of 2D materials and alters their properties. While the
surface contamination is studied using a plethora of techniques, the effect of
contamination on a confined system such as nanochannels, nanopores leading to
their clogging is still lacking. We report a systematic investigation of
hydrocarbon adsorption in the angstrom slit channels of varied heights. Hexane
is chosen to mimic the hydrocarbon contamination and the clogging of the
angstrom-channels is evaluated via a Helium gas flow measurement. The level of
the hexane adsorption, in other words, the degree of clogging depends on the
size difference between the channels and hexane. A dynamic transition of the
clogging and revival process is shown in sub-2 nm thin channels. Long-term
storage and stability of our angstrom-channels is demonstrated here up to three
years, alleviating the contamination and unclogging the channels using thermal
treatment. This study highlights the importance of the nanochannels stability
and demonstrates self-cleansing nature of sub-2 nm thin channels enabling a
robust platform for molecular transport and separation studies. We provide a
method to assess the cleanliness of the nanoporous membranes, which is vital
for the practical applications of nanofluidics in various fields such as
molecular sensing, separation and power generation.
