4 research outputs found
Layer-by-Layer Modification of Cation Exchange Membranes Controls Ion Selectivity and Water Splitting
The present study investigates the possibility of
inducing monovalent ion permselectivity on standard cation
exchange membranes, by the layer-by-layer (LbL) assembly of
poly(ethyleneimine) (PEI)/poly(styrenesulfonate) (PSS) polyelectrolyte
multilayers. Coating of the (PEI/PSS)N LbL
multilayers on the CMX membrane caused only moderate
variation of the ohmic resistance of the membrane systems.
Nonetheless, the polyelectrolyte multilayers had a substantial
influence on the monovalent ion permselectivity of the
membranes. Permselectivity comparable to that of a
commercial monovalent-ion-permselective membrane was obtained with only six bilayers of polyelectrolytes, yet with
significantly lower energy consumption per mole of Na+ ions transported through the membranes. The monovalent ion
permselectivity stems from an increased Donnan exclusion for divalent ions and hydrophobization of the surface of the
membranes concomitant to their modification. Double-layer capacitance obtained from impedance measurements shows a
qualitative indication of the divalent ion repulsion of the membranes. At overlimiting current densities, water dissociation
occurred at membranes with PEI-terminated layers and increased with the number of layers, while it was nearly absent for the
PSS-terminated layers. Hence, LbL layers allow switching on and turning off water splitting at the surface of ion exchange
membranes.The authors from Germany acknowledge support through the German Research Foundation (DFG) grant - SFB 985 "Functional Microgels and Microgel Systems". M.C. Marti-Calatayud is grateful to the Universitat Politecnica de Valencia for his postgraduate (Ref.: 2010-12) and visiting scientist grant (PAID-00-12). M. Wessling appreciates financial support from the Alexander-von-Humboldt Foundation.Abdu, S.; MartĂ Calatayud, MC.; Wong, JE.; GarcĂa GabaldĂłn, M.; Wessling, M. (2014). Layer-by-Layer Modification of Cation Exchange Membranes Controls Ion Selectivity and Water Splitting. ACS Applied Materials and Interfaces. 6(3):1843-1854. https://doi.org/10.1021/am4048317S184318546