Nafion/Zeolite Nanocomposite Membrane by in Situ Crystallization for a Direct Methanol Fuel Cell

A method for preparing Nafion/acid functionalized zeolite Beta (NAFB) nanocomposite membranes by in situ hydrothermal crystallization is described. The nanocomposite membranes have a slightly lower proton conductivity but a markedly lower methanol permeability (ca. 40% reduction). When tested with 1 M methanol feed, the direct methanol fuel cells (DMFCs) with the NAFB composite membranes have a slightly higher open circuit voltage (OCV; 3%) and much higher maximum power density (21%) than those with the pure Nafion 115 membranes. With a higher methanol concentration (5 M), the DMFCs with the NAFB composite membranes demonstrate a 14% higher OCV and a 93% higher maximum power density than those with the pure Nafion 115 membranes. Compared with the commercial Nafion 115 membranes, the NAFB composite membranes have slightly lower tensile strength but higher elastic modulus.