Interfacial Super‐Assembly of T‐Mode Janus Porous Heterochannels from Layered Graphene and Aluminum Oxide Array for Smart Oriented Ion Transportation

Salinity gradient energy existing in seawater and river water is a sustainable and environmentally energy resource that has drawn significant attention of researchers in the background of energy crisis. Nanochannel membrane with a unique nano‐confinement effect has been widely applied to harvest the salinity gradient energy. Here, Janus porous heterochannels constructed from 2D graphene oxide modified with polyamide (PA‐GO) and oxide array (anodic aluminum oxide, AAO) are prepared through an interfacial super‐assembly method, which can achieve oriented ion transportation. Compared with traditional nanochannels, the PA‐GO/AAO heterochannels with asymmetric charge distribution and T‐mode geometrical nanochannel structure shows directional ionic rectification features and outstanding cation selectivity. The resulting heterochannel membrane can achieve a high‐power density of up to 3.73 W m−2 between artificial seawater and river water. Furthermore, high energy conversion efficiency of 30.3% even in high salinity gradient can be obtained. These achievable results indicate that the PA‐GO/AAO heterochannels has significant potential application in salinity gradient energy harvesting. Here, a T‐mode Janus porous heterochannel from layered graphene and oxide array (PA‐GO/AAO) is prepared by a simple interfacial super‐assembly method. The asymmetric structure endows the PA‐GO/AAO heterochannels with directional ionic rectification features and outstanding cation selectivity. It can be further developed into a high‐performance salinity gradient energy harvesting device.