“…Owing to the exhaustion of traditional nonrenewable resources and increasingly severe global environmental problems, it is necessary to strike a better balance between energy security, environmental protection, and economic development. − As an abundant, sustainable, renewable, and stable energy resource, salinity gradient energy between the seawater and river water, which is also known as “blue energy”, can be harvested. − In theory, 0.8 kW of energy can be produced from every cubic meter water since the chemical potential differences are constructed with the salt concentration differences, which is almost comparable with the hydrostatic pressure energy that is harvested from a 280 m high water column. − This worldwide blue energy can be gathered by nanofluidic systems with cation- or anion-exchange nanochannels using membrane technologies, such as pressure-retarded osmosis (PRO) and reverse electrodialysis (RED). , Among them, RED attracts significant attention as it can directly transform the electrochemical potentials into electrical energy, and its applications are closely related with the nature of the ion exchange nanochannel membranes. − In recent years, various ion exchange nanochannel membranes with enhanced ion selectivity and high mass flux, such as single-layer MoS 2 nanopores, mesoporous carbon/anodic aluminum oxide (AAO), ordered mesoporous silica/AAO, heterogeneous MXene/PS- b -P2VP, polyamide modified graphene oxide/AAO, polymer polystyrenesulfonate (PSS) incorporated metal organic framework (MOF)/AAO, bacterial cellulose nanofiber/GO, and sulfonated poly(ether ketone)/AAO/polypyrrole composite membrane have been explored to assemble into salinity gradient power conversion devices. However, not only the competition of selectivity and permeability but also the instability and high cost of these nanochannel membranes have led to the low power density and further limit their realistic scale-up applications. , Thus, it is still necessary to develop a new type of nanochannel membrane through designing and controlling the characteristics of the nanomaterials to handle these practical challenges. , …”