  The emergence of new nanoporous materials, based e.g. on 2D materials, offers
new avenues for water filtration and energy. There is accordingly a need to
investigate the molecular mechanisms at the root of the advanced performances
of these systems in terms of nanofluidic and ionic transport. In this work, we
introduce a novel unified methodology for Non-Equilibrium classical Molecular
Dynamic simulations (NEMD), allowing to apply likewise pressure, chemical
potential and voltage drops across nanoporous membranes and quantifying the
resulting observables characterizing confined liquid transport under such
external stimuli. We apply the NEMD methodology to study a new type of
synthetic Carbon NanoMembranes (CNM), which have recently shown outstanding
performances for desalination, keeping high water permeability while
maintaining full salt rejection. The high water permeance of CNM, as measured
experimentally, is shown to originate in prominent entrance effects associated
with negligible friction inside the nanopore. Beyond, our methodology allows to
fully calculate the symmetric transport matrix and the cross-phenomena such as
electro-osmosis, diffusio-osmosis, streaming currents, etc. In particular, we
predict a large diffusio-osmotic current across the CNM pore under
concentration gradient, despite the absence of surface charges. This suggests
that CNMs are outstanding candidates as alternative, scalable membranes for
osmotic energy harvesting.
