Structure and dynamics of nanoscale electrical double layer

Electrical double layer (EDL) at substrate–solution interface plays essential roles in basic electrochemistry, energy conversion, desalination and separation, stochastic single-entity sensing, and other applications. The EDL structure generally refers to the inhomogeneous distribution of solution ions at the interfacial region. Dynamic changes in the EDL structure due to the transport of charges at the nanometer scale are the physicochemical origin of recently resolved novel nanotransport phenomena. High surface area materials and devices are potentially advantageous for better applications by providing more accessible interfaces. It is of high importance to emphasize that interfacial structures are indications of capacity, while the efficiency is often related to dynamics. This review discusses emerging transport phenomena under steady-state conditions and the transient deviations in prototype channel-type nanopores as unit elements for porous electrodes/membranes. The fundamental governing mechanism and structure–function correlations will be discussed in the context of energy harvesting and storage, desalination and phase transition, and resistive pulse sensing at the nanometer scale toward single-event/entity resolutions.