Experiment on intrinsically nonequilibrium distribution of large ions in charged small nanopores

Recent theoretical research on locally nonchaotic gravitational energy barrier led to an interesting finding: beyond the boundaries of Boltzmann's H-theorem, there may be macroscopic systems with nontrivial energy properties. The fundamental mechanism is rooted in the intrinsically nonequilibrium steady state. In the current investigation, we experimentally verify this concept, with the weak gravitational force being changed to the strong Coulomb force. The tests are performed on capacitive cells with the same nanoporous electrodes and various electrolyte concentrations. The key characteristic is that the nanopore size is only slightly larger than the ion size, less than twice the ion size. The confinement effect of the nanopore walls plays the role of the spontaneously nonequilibrium dimension (SND). At first glance, the capacitive cells exhibit "normal" charge curves. However, their steady-state ion distribution significantly differs from thermodynamic equilibrium. The measured potential difference is nearly an order of magnitude larger than the prediction of equilibrium thermodynamics. Such phenomena are in line with the molecular dynamics simulations reported in the open literature.