The interfaces of neat water and aqueous solutions play a prominent role in many technological processes and in the environment. Examples of aqueous interfaces are ultrathin water films that cover most hydrophilic surfaces under ambient relative humidities, the liquid/solid interface which drives many electrochemical reactions, and the liquid/vapor interface, which governs the uptake and release of trace gases by the oceans and cloud droplets. In this article we review some of the recent experimental and theoretical advances in our knowledge of the properties of aqueous interfaces and discuss open questions and gaps in our understanding.

Friction is one of the main sources of dissipation at liquid water/solid interfaces. Despite recent progress, a detailed understanding of water/solid friction in connection with the structure and energetics of the solid surface is lacking. Here we show for the first time that ab initio molecular dynamics can be used to unravel the connection between the structure of nanoscale water and friction for liquid water in contact with graphene and with hexagonal boron nitride. We find that whilst the interface presents a very similar structure between the two sheets, the friction coefficient on boron nitride is ≈ 3 times larger than that on graphene. This comes about because of the greater corrugation of the energy landscape on boron nitride arising from specific electronic structure effects. We discuss how a subtle dependence of the friction on the atomistic details of a surface, that is not related to its wetting properties, may have a significant impact on the transport of water at the nanoscale, with implications for the development of membranes for desalination and for osmotic power harvesting.Nanofluidics is an exciting field that offers alternative and sustainable solutions to problems relating to energy conversion, water filtration and desalination [1][2][3][4][5][6][7][8][9]. Miniaturization towards nanofluidic devices inevitably leads to an enhanced influence of surface and interface properties as opposed to those of the bulk. Friction is the most important interface property that limits fluid transport at the nanoscale, and its understanding is therefore crucial for the design of more efficient membranes, nanotubes and pores that exhibit low liquid/solid friction. The behavior of liquid flow at scales on the order of a few tens of nanometres departs from continuum fluid dynamics and desirable transport properties emerge at such small scales [10]. For instance, carbon nanotubes have a very high water permeability as compared to the prediction of macroscopic fluid dynamics [2]. Further, a vanishing friction has been found, giving rise to superlubric behavior of water chains inside tubes of sub-nanometre radii [11].Besides carbon, boron nitride (BN) nanostructures have recently been explored for the development of nanofluidic devices for fast water transport and efficient power generation [1,12,13]. Recent interest has been fueled by the demonstration that salinity concentration gradients across BN nanotube membranes can leed to the generation of very large electric currents [1]. It has also very recently been shown that there is a very large interlayer friction between in multiwalled BN nanotubes [14], as opposed to the superlubric behavior of the (homopolar) carbon nanotubes [15]. This suggests that the frictional properties of BN and C nanostructures might be quite different. However, to the best of our knowledge there has been no attempt to measure or compute the friction of water at the interface with BN sheets or nanotubes. Given that ab initio results have shown very similar contact angles of water drople...