Engineered Nanochannel Membranes with Diode-like Behavior for Energy Conversion over a Wide pH Range.

Electric eels can generate high potential bioelectricity because of the numerous electrocytes, where the cell membranes contain ion-selective channels. Net electric current is formed by the directional permeation of ions across the channels. Many nanofluidic devices have been designed for energy conversion. However, the challenge still remains of the fabrication of scalable ion-selective membranes with high power density. Inspired by the electric eels, we designed an asymmetric nanochannel membrane with diode-like ion transport behaviors, resulting in high performance energy conversion over a wide pH range. The nanochannel membranes were obtained from the polymeric nanochannels with carboxyl groups and the anodic alumina oxide (AAO) nanochannels bearing hydroxyl groups. At different pH conditions, the synergistic effect of the hybrid nanochannels ensured directional ion regulation, leading to energy conversion with high power density. The scalable, versatile nanochannel membranes have promising potential applications in the salinity gradient energy harvest from various sources.