Organic silica/Nafion® composite membrane for direct methanol fuel cells

Abstract

Organic silica with thiol group/Nafion ® composite membranes were prepared by the casting method using various additives including HS(CH2)3CH3Si(OCH3)2 (SH–), tetraethyl orthosilicate (TEOS) and HS(CH2)3CH3Si(OCH3)2-TEOS (HS-TEOS) in Nafion solutions. All composite membranes had an adulterated content of 5 wt%. SEM experiments indicated evenly distributed particles within all the Nafion composite membranes. The properties of the composite membranes in terms of methanol permeability, proton conductivity and cell performance were evaluated using a single cell of a direct methanol fuel cell (DMFC). The 125 μm SH-TEOS/Nafion composite membranes showed an approximately 50% decrease in methanol crossover compared with the commercial Nafion 117 membrane. The proton conductivity of the membrane was lowered slightly compared with that of Nafion 117. The SH-TEOS/Nafion membrane was more suitable for DMFCs with a high concentration of methanol than the pure Nafion membrane.