Artificially Designed Membranes Using Phosphonated Multiwall Carbon Nanotube−Polybenzimidazole Composites for Polymer Electrolyte Fuel Cells

Abstract

The ability of phosphonated carbon nanotubes to offer an unprecedented approach to tune both proton conductivity and mechanical stability of hybrid polymer electrolytes based on the polybenzimidazole membrane is demonstrated for fuel cell applications. The covalent attachment between the amino group of the 2-aminoethylphosphonic acid precursor and CNTs has been confirmed by NMR and IR experiments, while EDAX analysis indicates that one out of every 20 carbon atoms in the CNT is functionalized. Proton conductivity of the composite membrane shows a remarkable 50% improvement in performance, while a maximum power density of 780 and 600 mW cm−2 is obtained for the composite and pristine membranes, respectively. Finally, the ultimate strength determined for the composite and pristine membranes is 100 and 65 MPa, respectively, demonstrating the superiority of the composite. This study opens up a new strategy to systematically tune the properties of polymer electrolytes for special applications by using appropriately functionalized CNTs.

Novel composite Zr/PBI-O-PhT membranes for HT-PEFC applications

“…In order to enhance the mechanical strength, various polymers, such as PTFE [2–3] or polymer sulfonic acids, which can form ionic bonds with basic PBI (Nafion [4], SPEEK [5–6]), were proposed as functional fillers for PBI membranes. Even carbon nanotubes were impregnated into PBI matrices for a higher durability [7–8]. In order to improve the conductivity, proton conductors such as heteropolyacids (H 3 SiW 12 O 40 (SiWA) [9–12], H 3 PW 12 O 40 (PWA) [12], Cs 2.5 H 0.5 PMo 12 O 40 (CsPMoA) [13]), lithium hydraziniumsulfate, LiN 2 H 5 SO 4 , (LiHzS) [14] and Zr-containing compounds (zirconium pyrophosphate [15], zirconium tricarboxybutylphosphonate [16–17]) were introduced into PBI membranes.…”

Influence of carboxylated and phosphonated single‐walled carbon nanotubes on the transport properties of sulfonated poly(styrene‐isobutylene‐styrene) membranes

“…Most of the absorption bands of the CNTs are identical to those of the pCNTs. The CO stretching of the carboxylic groups present in the CNTs appears at 1717 cm −1 . Upon phosphonation, this band shifts to 1638 cm −1 due to the formation of the amide bond between the phosphonating agent and the COOH groups in the CNTs .…”

“…Phosphonation of the COOH SWCNTs (termed CNTs for simplicity) was performed as suggested by Kannan et al with several modifications (Fig. ) . The CNTs were washed with DI water to remove impurities and dried in an oven at 60 °C for 48 h. A volume of 100 mL of thionyl chloride (SOCl 2 ), 0.5 g of the purified CNTs, 500 mg of 2‐aminoethyl phosphonic acid (phosphonating agent), and 1 mL of dimethylacetamide were added to a three neck round flask and mixed for 5 min.…”

Polymer-Layered Silicate Nanocomposite Membranes for Fuel Cell Application

“…Several inorganic nanomaterials, such as layered silicates (clay) [1,7,[55][56][57], silica [58][59][60][61][62][63][64], polyhedral oligomeric silsesquioxane [65,66], titanium dioxide [56,67,68], zirconium dioxide [69,70], heteropolyacids [27,71], carbon nanotubes [72][73][74][75][76], and graphene oxides [77,78], are being used for the fabrication of organic-inorganic hybrid membranes for both PEMFC and DMFC applications. Layered silicates are known for their high barrier property towards gases and solvents due to their unique layered and platelet type structure [79].…”