Slip flow-enhanced streaming current in graphene oxide nanochannels*

In recent year, fast transport of water in carbon-based nanochannels due to the slip effect has attracted much attention. In this work, the pressure-driven streaming currents through sub-1nm nanochannels reconstructed by the layered material of graphene oxide (GO) was investigated experimentally and theoretically. The results show that the measured values of streaming current are 2\textasciitilde 3 orders of higher than the predicted values calculated from electrokinetic model under no-slip assumption. It is inferred that the streaming current is greatly enhanced due to the presence of water slippage in sub-1nm partial wetting GO nanochannels. In addition, it is found that the slip length is strongly dependent on the KCl concentration, i.e., surface charge density. The estimated slip length is from 1 to 22nm. The lower surface charge density (KCl concentration) reveals the larger slip length. It is believed that our finding is beneficial to develop a higher efficiency of electro-kinetic power generator and electro-osmotic pump.