Previous studies on nanofluidic salinity gradient power (NSGP), where energy associated with the salinity gradient can be harvested with ion‐selective nanopores, all suggest that nanofluidic devices having higher surface charge density should have higher performance, including osmotic power and conversion efficiency. In this manuscript, this viewpoint is challenged and anomalous counterintuitive pH‐dependent NSGP behaviors are reported. For example, with equal pH deviation from its isoelectric point (IEP), the nanopore at pH < IEP is shown to have smaller surface charge density but remarkably higher NSGP performance than that at pH > IEP. Moreover, for sufficiently low pH, the NSGP performance decreases with lowering pH (increasing nanopore charge density). As a result, a maximum osmotic power density as high as 5.85 kW m⁻² can be generated along with a conversion efficiency of 26.3% achieved for a single alumina nanopore at pH 3.5 under a 1000‐fold concentration ratio. Using the rigorous model with considering the surface equilibrium reactions on the pore wall, it is proved that these counterintuitive surface‐charge‐dependent NSGP behaviors result from the pH‐dependent ion concentration polarization effect, which yields the degradation in effective concentration ratio across the nanopore. These findings provide significant insight for the design of next‐generation, high‐performance NSGP devices.

中文翻译：

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pH异常的纳米流体盐度梯度幂

先前对纳米流体盐度梯度功率（NSGP）的研究表明，可以通过离子选择纳米孔收集与盐度梯度相关的能量，所有这些都表明具有较高表面电荷密度的纳米流体装置应具有更高的性能，包括渗透功率和转化效率。在本手稿中，这一观点受到了挑战，并报道了反常的，违反直觉的pH依赖性NSGP行为。例如，在等电点偏离其等电点（IEP）的情况下，与pH> IEP相比，pH <IEP的纳米孔显示出较小的表面电荷密度，但NSGP性能明显更高。此外，对于足够低的pH值，NSGP性能会随着pH值的降低（纳米孔电荷密度的增加）而降低。结果，最大渗透功率密度高达5.85 kW m在1000倍的浓度比下，pH 3.5时单个氧化铝纳米孔的转化效率为⁻²，而转化率为26.3％。使用严格的模型并考虑到孔壁上的表面平衡反应，证明了这些与直觉相反的与表面电荷有关的NSGP行为是由pH依赖性离子浓度极化效应引起的，从而导致整个纳米孔的有效浓度比下降。 。这些发现为下一代高性能NSGP器件的设计提供了重要的见识。