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

Abstract

Summary Air‐breathing proton exchange membrane fuel cells (AB‐PEMFCs) have a great potential for commercialization owing to their simple mechanical configuration and low cost compared with traditional proton exchange membrane fuel cells (PEMFCs). However, AB‐PEMFCs perform worse than traditional PEMFCs owing to the omission of the humidifier and a poor air supply system. In this study, hygroscopic metal oxide materials with good water absorption characteristics were employed in a Nafion membrane without humidification to compensate for the lack of performance owing to low proton conductivity. Among the various metal oxide materials, mesoporous structured silica has been synthesized with Nafion to increase the water content in nonhumidified conditions. The local morphological variation and surface charge distribution on the pristine Nafion and SiO2/Nafion composite membranes were analyzed by using multimode atomic force microscopy and force distance analyses. Several remarkable results were revealed, including considerable morphological changes and a locally separated water cluster network structure.

Analysis of Ionic Domains on a Proton Exchange Membrane using a Numerical Approximation Model based on Electrostatic Force Microscopy

“…From this, it can be surmised that the area of the ionic channels on the surface of a wet membrane increases by ~80% compared with that on a dry membrane. Previous experimental results have shown that there is an approximately 80% difference between proton conductivity in ambient conditions and fully humid conditions [31,32]. Hence, our calculations are consistent with the literature.…”

“…In this study, we determined the local charge density of a proton exchange membrane, which is directly related to the ionic domain, using an approximation model, and phase lag values obtained from electrostatic force microscopy. We also studied the variation of ionic channel networks in Nafion membranes in different conditions, with the results agreeing well with those of previous studies [31]. The enhancement of proton conductivity is prime purpose of developing the proton exchange membranes.…”

Potential of Nafion /eggshell composite membrane for application in direct methanol fuel cell

“…Referring to Table 3, water uptake for Nafion 117 was 44.61%, whereas that for recast Nafion and composite membranes N/E‐1, N/E‐3 and N/E‐5 were 72.48%, 73.91%, 87.27% and 77.24%, respectively. Composite membranes showed higher water uptake than the pristine Nafion membrane owing to the hygroscopic nature of carbonate particles 56 . An increasing trend was observed as the loading weight of filler increased from 1 to 3 wt% and then plummeted as the loading weight was further upsurged to 5 wt%.…”

Precise Molecular‐Level Modification of Nafion with Bismuth Oxide Clusters for High‐performance Proton‐Exchange Membranes

“…Tapping-mode atomic force microscopy (AFM) was further utilized to detect the surface morphology and nanophase separation structure of hybrid membranes. [18] As seen from Figure 1c,d and Figure S8-S11, all RN,Nafion-Bi 12 -3 % and Nafion-Bi 12 -5 %h ybrid membranes show typical fingerprint images of surface morphology with the height of about 0nmt o4 .8 nm, in which the dark and bright districts represent the hydrophilic ionic nanophase and hydrophobic Nafion-backbone nanophase,r espectively.C ompared with RN,t he Nafion-Bi 12 -3 %m embrane exhibited the enhanced connectivity for both the hydrophilic and hydrophobic nanophases,a nd the hydrophilic channels were significantly widened after {H 6 Bi 12 O 16 }a ddition. However,f or the Nafion-Bi 12 -5 %m embrane,t he excessively added {H 6 Bi 12 O 16 } clusters disturb the hydrophobic/hydrophilic nano-phases, which are also demonstrated by the apparent irregularity in the surface roughness ( Figure 1d and Figure S10-S11).…”