Embedding MXene nanosheets into cation exchange membranes to enhance power generation by reverse electrodialysis

Abstract

Electrical energy can be extracted from the mixing of two water streams with different salinity through the reverse electrodialysis (RED) technique. Ion exchange membranes (IEMs) are vital components for capturing the energy in the RED systems. Therefore, the design and fabrication of IEMs are essential to the enhancement of power production by the RED system. In this work, the novel cation exchange membranes (CEM) were prepared by sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) as a polymer and MXene nanosheets as filler for the first time. The effect of polymer concentration and MXene loading on the electrochemical properties, membrane structure, and gross power output in the RED system was investigated in detail. An increase in MXene additive (0 to 2 %) significantly increased the permselectivity from 77.40 % to 91.25 %, and reduced the area resistance from 4.7 to 1.3 Ω.cm2 of fabricated CEMs (sPPO: 22 wt%). The results also showed that CEM was prepared by a solution containing 22 wt% of sPPO (1 wt% of MXene additive), and 19 wt% of sPPO (2 wt% of MXene additive) exhibited relatively desirable electrochemical properties for power generation. These membranes presented the highest gross power density (1.45 and 1.37 W.m−2, respectively) in RED experiments, which were significantly higher than the commercially available CMX membrane (1.01 W.m−2).