Transport of neutral and charged solutes in imidazolium-functionalized poly(phenylene oxide) membranes for artificial photosynthesis

Anion exchange membranes (AEMs) play an essential role in artificial photosynthesis devices, which photoelectrochemically convert carbon dioxide and water into useful products. AEMs allow the transport of charge carriers between electrodes while minimizing the transport of CO2 reduction products. Fundamental transport studies in AEMs relevant to artificial photosynthesis are uncommon. Herein, we describe the preparation of an imidazolium-functionalized poly(phenylene oxide) membrane. Membrane transport properties were controlled by systematic variation of the degree of imidazolium functionalization. Ethanol (a common CO2 reduction product) permeability and ionic conductivity increased with degree of functionalization and with membrane water volume fraction. Consequently, membranes of relatively high ionic conductivity exhibited relatively high ethanol permeability, presenting a tradeoff in the transport properties desirable for artificial photosynthesis applications. This work seeks to enable optimization...