Low-Cost Nanomaterials for High-Performance Polymer Electrolyte Fuel Cells (PEMFCs) - Low-cost Nanomaterials: Toward Greener and More Efficient Energy Applications - page 359

Table 1 Variation of proton conductivity, domain size and yield strength with s-MWCNT
composition and water content
Membrane composite Proton

conductivity
(S cm -1 )

Hydrophilic domain
size (nm)

Water
content (%)

Yield strength
(MPa)

Nafion 115 0.028 48 29.2 2.68

Recast Nafion 0.020 51 42.3 2.40

Naf-s-MWCNT 0.01 % 0.029 54 39.7 2.50

Naf-s-MWCNT 0.05 % 0.036 72 33.4 2.62

Naf-s-MWCNT 0.1 % 0.032 70 30.4 2.67

Naf-s-MWCNT 0.5 % 0.031 67 28.1 3.10

Naf-s-MWCNT 1 % 0.030 35 27.2 4.30

Fig. 4 Scheme for the surface modification of MWCNTs and Pt nanoparticles deposition
(adapted from Ref. [ 66 ] with permission from Elsevier publishing company)

chemical modification route [ 66 ]. By this method Pt nanoparticles of 1-3 nm are
stabilized at the same time maintaining a uniform Pt distribution due to the
anchoring groups present on the CNT surface (Fig. 4 ). Interestingly, fuel cell
polarization plot with this catalyst shows a power density of 1,110 mW cm -2
against 800 mW cm -2 (5 cm 2 area) observed for a commercial catalyst. Further,
the activation loss observed at 50 mA cm -2 is only 50 mV from the OCV for this
surface-modified process compared to that of 150 mV for unmodified CNTs.
However, with the carbon black it is much higher, which signifies the more effi-
cient use of CNTs in the catalyst layer of PEMFCs.