Anomalous Channel‐Length Dependence in Nanofluidic Osmotic Energy Conversion

Cao, Liuxuan; Xiao, Feilong; Feng, Yining; Zhu, Wei; Geng, Wen-Xiao; Yang, Jinlei; Zhang, Xiaopeng; Li, Ning; Guo, Wei; Jiang, Lei

doi:10.1002/adfm.201604302

Cited by 133 publications

(146 citation statements)

References 47 publications

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“…To take the pore-pore interactions into consideration, besides the investigated nanopore, we also calculate the diffusive ion transport through its nearest neighboring nanopores. [10] The validity of the PNP model has been verified by many previous works by us [22][23][24] and other groups. The numeric pore density varied from 1×10 6 to 1×10 10 pores/cm 2 .…”

Section: Resultsmentioning

confidence: 59%

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Anomalous Pore‐Density Dependence in Nanofluidic Osmotic Power Generation

Tang

et al. 2018

Chin. J. Chem.

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Osmotic power generation in biomimetic nanofluidic systems has attracted considerable research interest owing to the enhanced performance and long-term stability. Towards practical applications, when extrapolating the materials from single-nanopore to multi-pore membranes, conventional viewpoint suggests that, to gain high electric power density, the porosity should be as high as possible. However, recent experimental observations show that the commonly-used linear amplification method largely overestimates the actual performance, particularly at high pore density. Herein, we provide a theoretical investigation to understand the reason. We find a counterintuitive pore-density dependence in high porosity nanofluidic systems that, once the pore density approaches more than 1×10 9 pores/cm 2 , the overall output electric power goes down with the increasing pore density. The excessively high pore density impairs the charge selectivity and induces strong ion concentration polarization, which undermines the osmotic power generation process. By optimizing the geometric size of the nanopores, the performance degradation can be effectively relieved. These findings clarify the origin of the unsatisfactory performance of the current osmotic nanofluidic power sources, and provide insights to further optimize the device.

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Section: Resultsmentioning

confidence: 59%

“…[10,23] By reducing the diameter of the model nanopores from 32 to 20 nm, the power density monotonously grows up with the increasing pore density (Figure 5a). The charge selectivity and ICP effect are related to the geometry of the nanopores.…”

Section: Figurementioning

confidence: 99%

Anomalous Pore‐Density Dependence in Nanofluidic Osmotic Power Generation

Tang

et al. 2018

Chin. J. Chem.

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“…Here we investigate the NSGP with a pH‐regulated (e.g., alumina) nanopore by adopting the model composed of the multi‐ion PNP and Navier–Stokes (NS) equations (see detail in Supporting Information). In contrast to the existing works, the present model takes into account the multicomponent ionic species, chemical equilibrium reactions on the pore wall, and diffusioosmotic flow, and its applicability is validated by the existing experimental data of the osmotic current, induced by the salinity gradient, in a single BNNT (Figure S1, Supporting Information). As will be shown later, we, for the first time, report the anomalous pH‐dependent NSGP behaviors; that is, the nanopore having higher surface charge density can exhibit worse NSGP performance.…”

Section: Introductionmentioning

confidence: 93%

“…In addition to experimental efforts, many simulation works have been made to understand clearly fundamental mechanisms that are helpful for explaining experimental findings as well as providing guidelines to the design of next‐generation, high‐performance NSGP systems . In these simulations, the well‐known Poisson–Nernst–Planck (PNP) equations were used along with the generalized assumption of a constant surface charge density on the nanopore wall . This implies that the surface charge density is a prescribed parameter, instead of being obtained as functions of the material and solution properties.…”

Section: Introductionmentioning

confidence: 99%

Anomalous pH‐Dependent Nanofluidic Salinity Gradient Power

Yeh

Chen

Chiou

et al. 2017

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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 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.

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“…[38] However, in a recent study, Cao et al found that, for short-channellength nanopores (L < 400 nm), the generated electric power decreases on reducing the pore channel length, showing anomalous pore-channel-length dependence. [39] The excessively short pore length induces strong ion concentration polarization, particularly at the low-concentration end, which eventually weakens the charge selectivity of the nanopores. [40] Therefore, the optimal pore length should be in the range of 400 to 1000 nm.…”

Section: Energy Conversion In 1d Nanofluidic Systemsmentioning

confidence: 99%

Bioinspired Energy Conversion in Nanofluidics: A Paradigm of Material Evolution

et al. 2017

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fly. Many of the well-developed structurefunction relationships in biological systems have become the inspiration for the design and application of innovative materials. [2,3] This bioinspired learning process accelerates the continuous evolution of novel man-made materials, circumventing many of the previously insurmountable challenges in, for example, architecture, aerodynamics, and materials science, etc. [4] More intriguingly, by adopting various design strategies from different natural inspirations, synthetic materials and devices keep on evolving and gaining more functions. Taking the development of aircraft for example, the wing curve of the prototype airplane mimics the streamlined shape of bird wings so as to reduce aerodynamic drag. The bat uses supersonic-based pathfinding to avoid obstacles when flying at night. Learning from this skill, modern aircraft use radar navigation systems as their "eyes". The adaptive surface coatings of aircraft mimic the micro-and nanostructures of shark skin, which greatly reduces frictional resistance, saving fuel and preventing damage from ultraviolet irradiation. As human beings constantly get new inspiration from nature, the evolution of bioinspired materials never stops.Research in nanofluidic energy conversion is enlightened by the electrogenic cells that convert transmembrane ion-concentration gradients into the release of electrical impulses by membrane-protein-regulated ion transport through the hierarchically arranged ion channels and ion pumps. [5] One particular example is electric eels (Electrophorus electricus), which are capable of generating electric shocks up to 600 V for predation and self-defense (Figure 1). Toward this goal, one research direction is to build synthetic nanofluidic devices with a minimum set of components, yet can mimic the biological energyconversion process on the nanoscale. [6] Another research direction is the multiscale integration of individual nanofluidic devices into macroscopic materials for practical use. [7] Here, we present an overview of the structural and functional evolution in synthetic one-dimensional (1D) and two-dimensional (2D) nanofluidic systems under the guidance of three different types of biological inspiration: the asymmetric ion-transport behaviors of biological ion channels, the strong bioelectric function of electric eels, and the layered microstructure of nacre. The progress, challenges, and future perspectives in this growing field are highlighted.Well-developed structure-function relationships in living systems have become inspirations for the design and application of innovative materials. Building artificial nanofluidic systems for energy conversion undergoes three essential steps of structural and functional development with the uptake of separate biological inspirations. This research field started from the mimicking of the bioelectric function of electric eels, wherein a transmembrane ion concentration gradient is converted into ultrastrong electrical impulses via membrane-protein-regulated ion tran...

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Anomalous Channel‐Length Dependence in Nanofluidic Osmotic Energy Conversion

Cited by 133 publications

References 47 publications

Anomalous Pore‐Density Dependence in Nanofluidic Osmotic Power Generation

Anomalous Pore‐Density Dependence in Nanofluidic Osmotic Power Generation

Anomalous pH‐Dependent Nanofluidic Salinity Gradient Power

Bioinspired Energy Conversion in Nanofluidics: A Paradigm of Material Evolution

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