High-performance osmotic energy conversion requires both large ionic throughput and high ionic selectivity, which can be significantly promoted by exterior surface charges simultaneously, especially for short nanopores. Here, we investigate the enhancement of ionic diffusion by charged exterior surfaces under various conditions and explore corresponding effective charged areas. From simulations, ionic diffusion is promoted more significantly by exterior surface charges through nanopores with a shorter length, wider diameter, and larger surface charge density or under higher salt gradients. Effective widths of the charged ring regions near nanopores are reversely proportional to the pore length and linearly dependent on the pore diameter, salt gradient, and surface charge density. Due to the important role of effective charged areas in the propagation of ionic diffusion through single nanopores to cases with porous membranes, our results may provide useful guidance to the design and fabrication of porous membranes for practical high-performance osmotic energy harvesting.

中文翻译：

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在盐梯度下通过纳米孔增强离子扩散的有效带电外表面

高性能渗透能转换需要大的离子通量和高离子选择性，这可以同时通过外表面电荷显着促进，特别是对于短纳米孔。在这里，我们研究了在各种条件下带电外表面对离子扩散的增强作用，并探索了相应的有效带电区域。根据模拟，通过具有较短长度、较宽直径和较大表面电荷密度或在较高盐梯度下的纳米孔的外表面电荷更显着地促进离子扩散。纳米孔附近带电环区域的有效宽度与孔长度成反比，并与孔径、盐梯度和表面电荷密度线性相关。