Sulfonated graphene oxide/Nafion composite membranes for high temperature and low humidity proton exchange membrane fuel cells

Abstract

Iron oxide (Fe 3 O 4 ) nanoparticles anchored over sulfonated graphene oxide (SGO) and Nafion/Fe 3 O 4 -SGO composites were fabricated and applied as potential proton exchange membranes in proton exchange membrane fuel cells (PEMFCs) operated at high temperature and low humidity. Fe 3 O 4 nanoparticles bridge SGO and Nafion through electrostatic interaction/hydrogen bonding and increased the intrinsic thermal and mechanical stabilities of Nafion/Fe 3 O 4 -SGO composite membranes. Nafion/Fe 3 O 4 -SGO composite membranes increased the compactness of ionic domains and enhanced the water absorption and proton conductivity while restricting hydrogen permeability across the membranes. The proton conductivity of Nafion/Fe 3 O 4 -SGO (3 wt%) composite membrane at 120 C under 20% relative humidity (RH) was 11.62 mS cm À1, which is 4.74 fold higher than that of a pristine recast Nafion membrane. PEMFC containing the Nafion/Fe 3 O 4 -SGO composite membrane delivered a peak power density of 258.82 mW cm À2 at a load current density of 640.73 mA cm À2 while operating at 120 C under 25% RH and ambient pressure. In contrast, under identical operating conditions, a peak power density of only 144.89 mW cm À2 was achieved with the pristine recast Nafion membrane at a load current density of 431.36 mA cm À2. Thus, Nafion/Fe 3 O 4 -SGO composite membranes can be used to address various critical problems associated with commercial Nafion membranes in PEMFC applications.

Study of morphological characteristics on hydrophilicity‐enhanced SiO 2 /Nafion composite membranes by using multimode atomic force microscopy

“…Thus, the characterization of morphology variation owing to the composition with inorganic pillar materials is crucial to the understanding of composite membranes. Many groups reported that the water uptake and proton conductivity increased because the hydrophilic ionic cluster network changes and the hygroscopic characteristics are improved by the sulfonized fillers materials . Lee et al studied the proton conductivity of SPAEK block copolymer membranes with a controlled F‐oligomer length bearing a pendant diphenyl unit.…”

“…The SGO increased the number of –SO 3 H groups per cluster volume domain, and Fe 3 O 4 induced the hydrogen bonding networks between the –SO 3 H groups. Accordingly, the water uptake, ion exchange capacity, and proton conductivity of the composite membrane increased owing to these changes …”

“…Many groups reported that the water uptake and proton conductivity increased because the hydrophilic ionic cluster network changes and the hygroscopic characteristics are improved by the sulfonized fillers materials. [17][18][19] Lee et al 17 studied the proton conductivity of SPAEK block copolymer membranes with a controlled F-oligomer length bearing a pendant diphenyl unit. According to this study, increasing the length of the hydrophilic oligomer in the main chain induces clear separation of hydrophobic and hydrophilic regions.…”

Membrane‐hydration‐state detection in proton exchange membrane fuel cells using improved ambient‐condition‐based dynamic model

“…PEMFC offers many advantages, such as high efficiency, silent operation, zero greenhouse-gas emission, and most importantly, high energy density. [4][5][6][7][8][9] Most of the aforementioned voltage drops are difficult to calculate, because some model parameters, such as the internal current (I int ), exchange current density (I o ), charge-transfer coefficient (α), and maximum limiting current (I lim ) for a PEMFC vary with ambient temperature and PEMFC loading conditions. 1,2 In PEMFC systems, hydrogen is supplied to the anode while ambient oxygen is supplied to the cathode.…”

Novel sulfonated multi‐walled carbon nanotubes filled chitosan composite membrane for fuel‐cell applications

“…To overcome these problems, Si, Ti, Zr, and phosphonate functionalized CNT are commonly used for modification of PEM . Recently, carbon nanomaterials (MWCNTs and fullerene) with sulfonic acid groups have been widely used in the fabrication of composite membranes . Liu et al .…”