Electrokinetic energy conversion in nanochannels with surface charge-dependent slip

Abstract

Electrokinetic energy conversion in nanochannels has attracted increasing attention in recent years. However, few scholars have studied the impact of the intrinsic distinction between surface charge-dependent and independent slip on power generation performance. In this work, we consider three kinds of boundary conditions, including no slip, independent slip and surface charge-dependent slip, to investigate the ion concentration distribution, velocity and energy conversion performance in nanochannels combined with the electric double layer theory. The results show that the boundary slip can improve the output performance significantly. Besides, due to the restriction of surface charge on boundary slip, the power generation performance under independent slip and dependent slip exhibits a significant deviation. Thus, the independent slip model is not suitable for predicting ion transport and fluidic flow in practical applications. Moreover, the ion concentration and channel height also play an optimizing role in the performance of electrokinetic energy conversion. We find the boundary slip is a benefit to promote the ion flux due to the velocity mechanism but has little effect on ion concentration distribution. The findings of this study can help for better understanding the ion transfer behavior in nanochannels, which provides useful information for the design and optimization of nanochannel power generation.