Abstract
This study explores enhancing salinity gradient power using 2D materials
due to their surface-governed charge. However, achieving high-performing
membranes with superior ion selectivity and low ionic resistances
remains challenging. To address this issue,
Al(OH)4- anions were incorporated into
graphene oxide membranes to increase their spontaneous negative surface
charge. The anions were successfully formed and encapsulated through a
reaction with the alumina support under alkaline conditions during the
membrane formation. The membranes’ physicochemical properties were
analyzed by means of selected characterization techniques. The
incorporation of Al(OH)4- anions
significantly improved permselectivity and ionic resistance, reaching
approximately 95% and 2 Ω cm2, respectively. A
modeling of the system was carried out to further understand the
anchoring of these ions within the membrane matrix and their role in
boosting the charge of the membrane and, therefore, their
electrochemical properties. The study delved into the utilization of GO
membranes as monovalent-selective membranes, an approach to boost
reverse electrodialysis power densities. The membranes demonstrated
impressive selectivity, overcoming 70 folds for divalent cations over
K+.