Organic-inorganic hybrid alkaline membranes by epoxide ring opening for direct methanol fuel cell applications

Recently, alkaline or anion-exchange membranes (AEMs) have attracted remarkable interest for direct methanol fuel cells (DMFCs) application, operated at intermediate temperature (100–200 °C). In this manuscript, we report synthesis of organic–inorganic hybrid anion-exchange silica precursor (AESP) with ammonium functionality by ring opening of glycidoxypropyltrimethylammonium chloride under mild heating condition. A simple and ecofriendly procedure based on sol–gel method was used for the preparation of hydroxide conductive organic–inorganic AESP–poly(vinyl alcohol) (PVA) cross-linked AEM in aqueous media. Developed AEMs were extensively characterized for their physicochemical and electrochemical properties under DMFC operating conditions. These membranes were designed to possess all the required properties of highly ion conductive membrane, namely reasonable swelling, dimensional and oxidative strength, flexibility, low methanol permeability along with reasonable hydroxyl ion conductivity (7.57 × 10−2 S cm−1) due to quaternary ammonium group functionality. Reported AEM-100 showed 7.57 × 10−2 S cm−1 membrane conductivity much higher than reported values (0.30–3.40 × 10−2 S cm−1) for other AEMs in the literature. Moreover, from the selectivity parameter among all developed membranes, AEM-100 (100 wt% to PVA of AESP in the membrane matrix), exhibited best result for alkaline DMFC applications.