Investigation of power generation from concentration gradient by reverse electrodialysis in ion-selective nanostructures

Abstract

Power generation by reverse electrodialysis is experimentally investigated by placing nanostructures between two sodium chloride solutions with various combinations of concentrations. Bare and silica-coated alumina nanopore arrays and sintered silica nanoparticles are used in the present study. The current-potential characteristics are measured for various electrolyte concentration levels. The transference number and the electrical conductance of nanostructures are obtained from these characteristics. The transference numbers of the bare and silica-coated alumina nanopore arrays were 0.30 and 0.72, respectively; these values were nearly independent of the concentration of the sodium chloride solutions when it was less than 200 mM. Therefore, the bare and silica-coated alumina arrays can be used as anion-selective and cation-selective membranes, respectively, for micro batteries and micro power generators. The transference number of the sintered silica nanoparticles, which can be used as a cation-selective membrane, is 0.6. Finally, power generation by reverse electrodialysis using an alumina nanopore array is presented. The highest power generation measured is 542 nW, which was several orders of magnitude higher than those measured in previous studies based on nanofluidic channels or nanopores.