Novel methanol blocking proton exchange membrane achieved via self anchoring phosphotungstic acid into chitosan membrane with submicro pores
Abstract A novel chitosan/phosphotungstic acid composite proton exchange membrane was prepared by self anchoring phosphotungstic acid into chitosan membrane with submicro pores smp CTS/HPW) The smp CTS/HPW membrane exhibits enhanced proton conductivity and excellent methanol blocking performance. The proton conductivity of the composite membrane is significantly affected by the content of HPW which could be modulated by introducing soft template P123 into the membrane to obtain varied porosity. The highest proton conductivity s of the composite membrane, 2.9x10 2 S cm 1 at 80 degC, was achieved with soft template P123 content of 40% Moreover, the smp CTS/HPW membrane showed very stable proton conductivity under deionized water condition due to HPW molecules self anchored in the CTS matrix. The methanol permeability P of 40% smp CTS/HPW membrane was 4.7x10 7 cm 2 s 1 which was 60% lower than that of Nafion 212 membrane. The highest selectivity factor s P 2.27x10 4 S cm 3 s, was obtained on 40% smp CTS/HPW membrane. A direct methanol fuel cell (DMFC) based on the 40% smp CTS/HPW membrane achieved a peak power density of 16 mW/cm 2 at 80 degC. This study indicates the promising potential of smp CTS/HPW membrane as alternative proton exchange membrane for DMFCs application.