A sandwich structured membrane for direct methanol fuel cells operating with neat methanol

Water starvation at the anode represents a challenging issue in the development of direct methanol fuel cells (DMFCs) operating with neat methanol. To tackle the issue, a multi-layered membrane, consisting of an ultra-thin reaction layer sandwiched between two thin membranes, is proposed and developed. The reaction layer is composed of well-dispersed PtRu catalysts, SiO2nanoparticles and Nafion ionomers. During the fuel cell operation, the methanol permeated from the anode catalyst layer and the oxygen permeated from the cathode catalyst layer meet and react in the reaction layer of the sandwich structured membrane to form water and CO2. The produced water is then maintained at a relatively high level by the hygroscopic SiO2nanoparticles in the sandwich structured membrane. As a result, such a created water source at a high concentration level can supply the water required not only for the anode methanol oxidation reaction but also for membrane hydration. The performance characterization demonstrates that the DMFC with the sandwich structured membrane results in much higher performance than that with a single layer Nafion membrane does.