EXPERIMENTAL STUDY ON ENERGY HARVESTING FROM SALINITY GRADIENT BY REVERSE ELECTRODIALYSIS IN AG/AGCL DEPOSITED AAO NANOCHANNEL ARRAY

Reverse electrodialysis(RED) is energy conversion phenomena which generates electricity from concentration gradient energy by mixing the ions in sea water with fresh water through ion-selective nanochannel. When nanochannels are filled with an aqueous solution, the surface of nanochannels is charged by ionization, ion adsorption, and ion dissolution. Therefore, co-ions are repelled from the nanochannels and only counter-ions can be transported through the nanochannels. As a result, the electric current can be generated by selective ion transport through the nanochannels from sea water to fresh water. Recently, solid-state nanochannels or nanopores have received attention because they have potential to replace polymer ion-selective membranes. Especially, anodic aluminum oxide (AAO) nanochannel array has advantage of easiness of pore size control and high pore density. In the present study, to collect electric current generated by the nanochannels, we deposited the porous silver layer on both front and rear surface of the AAO nanochannel array by using e-beam evaporation and changed the silver layer to the silver / silver chloride layer by chemical oxidation with aqueous FeCl3. Finally, we conduct an experimental investigation for the power generation from the AAO nanochannel arrays placed between two potassium chloride solutions with various combinations of concentrations.