Performance enhancement of direct methanol fuel cells using a methanol barrier boron nitride–Nafion hybrid membrane

Abstract

Sulfonated hexagonal boron nitride is explored as a potential filler to prepare Nafion hybrid membranes for direct methanol fuel cell (DMFC) applications. The layered morphology of h-BN effectively suppresses the methanol crossover in the Nafion–h-BN membrane, while the presence of sulfonic acid groups improves the proton conductivity by providing an additional pathway for proton transport. Consequently, the Nafion–h-BN hybrid membranes display a significantly reduced methanol crossover current density. On the other hand, the optimized Nafion–h-BN hybrid membrane displays a proton conductivity of 214 mS cm⁻¹, which is ∼58% higher than that of the pristine Nafion membrane. The single-cell DMFC employing Nafion–h-BN (0.75 wt%) membrane delivers a peak power density of 165 mW cm⁻² at 70 °C, while only a peak power density of 65 mW cm⁻² is achieved with the pristine Nafion under similar operating conditions.