Theoretical analysis and experiment on large ions adsorbed in charged small micropores: A highly nonequilibrium system

In this research, we investigate the concept of locally nonchaotic barrier. The barrier can be either an energy barrier or an entropy barrier. The barrier width is much less than the nominal mean free path of the particles, so that the particle-barrier interaction tends to be nonchaotic. Our analyses suggest that under the condition of local nonchaoticity, the steady-state particle distribution cannot reach thermodynamic equilibrium. It has interesting effects: When the system is operated in an isothermal cycle, the produced work may be effectively more than the consumed work; when the barrier forms an asymmetric couple with an equilibrium counterpart, at the steady state, the particle velocity distribution may be anisotropic. The theorical and numerical results were validated by an experiment on large ions adsorbed in small charged micropores. The ion size was slightly less than the micropore diameter, but larger than the micropore radius. The testing data demonstrated a large voltage difference, as the ion concentration was varied.



Although these phenomena seem counterintuitive, they strictly follow the basic principle of maximum entropy. What makes the system unique is that the narrow barrier interrupts the probability distribution of local microstates. This finding will have profounds impact on many aspects of statistical mechanics. It may enable high-efficiency heat and mass transfer, high-power energy harvesting, novel metamaterials, etc.