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In this paper, composite proton exchange membranes (PEMs) based on functionalized graphene oxide (NGO) and carboxylated sulfonated poly aryl ether ketone sulfone (C-SPAEKS) were successfully synthesized. Functionalized graphene oxide was synthesized using graphene oxide as a substrate, and then diethylenetriamine (DETA) was chemically bound to the graphene oxide. The 1H NMR, FT-IR and XPS were used to characterize the NGO and composite membranes. The results show that the composite membranes have good proton conductivity, dimensional stability and electrochemical performance. The swelling rate of all the composite membranes was less than 18%, which indicates that they have good dimensional stability. Compared to C-SPAEKS membrane (34.8 mS cm-1 at 20 °C, 109.8 mS cm-1 at 90 °C), the proton conductivities of C-SPAEKS/GO-0.75 membrane (52.4 mS cm-1 at 20 °C, 171.1 mS cm-1 at 90 °C) were significantly improved. Meanwhile, the C-SPAEKS/NGO-0.75 achieved peak power density of 407.77 mW cm-2 at high OCV of 0.9576 V. Such a result is much superior to the C-SPAEKS membrane (0.8973 V, 190.72 mW cm-2) and the Nafion 117 (0.99 V, 302 mW cm-2), and demonstrated good single-fuel cell performance. In summary, it can be well concluded that functionalized GO as filler makes an significant contribution in improving the overall performance of the composite membranes. • Functionalized GO containing amino group was synthesized. • An efficient and orderly proton transport channel was constructed. • The hybrid PEMs showed good proton conductivity (171.1 mS cm-1, at 90 °C). • The hybrid PEMs showed good single cell performance (407.77 mW cm-2, 80 °C, 100% RH). • Acid-base combination could improve proton conductivity effectively. [ABSTRACT FROM AUTHOR]

[Display omitted] Introduction of carbazole-based monomers with multiple branching sites into polymer backbone ensures excellent ionic exchange capacity while enhancing the dimensional stability and alkaline stability of AEMs, expanding the application prospects of branched structures in AEMs. • The unique branching polymer backbone structure was constructed to enhance the dimensional stability of AEMs. • The introduction of monomeric CBP into the polymer backbone broadened the microporous channels within the AEMs and facilitated OH– transport. • Branching main chain structure for excellent alkaline stability of AEMs. In the technological development of anion exchange membrane fuel cells (AEMFCs), it is crucial to prepare anion exchange membranes (AEMs) with high conductivity and excellent dimensional stability. This study successfully developed highly branched poly(aryl piperidinium) AEMs by introducing 4,4′-bis(N-carbazolyl)-1,1′-biphenyl as branched linker unit into the poly(p-terphenyl piperidinium) backbone. With the introduction of the carbazole group, the plane-conjugated structure and non-rotatable properties are fully utilised, which effectively reduces the entanglement between the polymer backbones and increases the free volume of the AEMs, hence facilitates the construction of an efficient ion transport channel. The branched structure effectively reduces the water uptake of the membrane which leads to improved dimensional stability. The optimized QPCBP-TP-7 membrane exhibited high conductivity, reaching up to 151.88 mS cm−1 at 80 °C, along with excellent mechanical strength (TS = 42.51 MPa, EB = 13.32 %, wet state) and dimensional stability (SR of 22.9 % at 80 °C). Surprisingly, this membrane also exhibited favorable antioxidant properties (retaining over 97.28 % weight after 96 h in Fenton's reagent at 80 °C), and alkaline stability (retaining over 86.81 % efficacy after 1500 h in 5 M NaOH solution at 80 °C). In AEMFCs applications, the QPCBP-TP-7 membrane achieved peak power density (PPD) up to 616 mW cm−2 with the current density is 1330 mA cm−2 at 80 °C (H 2 -O 2) and the QPCBP-TP-7 membrane remained stable and hardly degraded when operated at constant current of 0.1 A cm−2 (80 °C) over 100 h. [ABSTRACT FROM AUTHOR]

Anion-exchange membranes (AEMs) have gained widespread attention as another rising star among the core components of fuel cells. However, the disadvantages of low electrical conductivity and poor chemical stability greatly limit its development. Here, indeno carbazole monomers were introduced into the ether-free backbone and hydrophilic alkoxy side chains were suspended from the side chains to prepare a series of poly (indeno carbazolyl-aryl) piperidine membranes. Indeno carbazole is a nitrogen-containing heterocyclic compound with a large conjugation system, which provides a large volume of space to avoid close stacking of polymer molecules, and provides a place for the aggregation of water molecules without excessive swelling. The hydrophilic alkoxy side chain, as a hydrophilic group, absorbs a large amount of water and at the same time the oxygen atom will form cation-dipole interactions with the cation to induce cation aggregation. In addition, the polarity difference between the hydrophobic main chain and the hydrophilic side chain creates an obvious microphase separation structure, and the high-water absorption generated by the two can also reduce the attack of alkali on the cations, thus further improving the chemical stability of the membrane. At 80 °C, the relatively low IEC qPTP-IC-O-9% membrane instead achieved the highest ionic conductivity (137.5 mS cm−1) and peak power density (406 mW cm−2), and the conductivity retention was at 97.9% after 1300 h of immersion in 3 M NaOH at 80 °C. In addition, the qPTP-IC-O-9% membrane maintained 71.7% of the initial voltage after 30 h durability test at 80 °C, 0.05 A cm−2. To sum up, the qPTP-IC-O-9% membrane has a very bright future in promoting the further rapid development of hydroxide fuel cells. [Display omitted] • Introduction of bulky monomers to increase free volume and cation clusters. • Grafting alkoxy chains build polar differences and cation-dipole interactions. • Main and side chains synergistically optimize conductivity and alkali stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Biological based nanosheet ATP@GO fillers were synthesized. • An efficient and orderly proton transport channel was constructed. • The hybrid PEMs showed good proton conductivity and the single cell performance. • Adenosine triphosphate act as a proton acceptor, donor and transport sites. In this study, composite proton exchange membranes (PEMs) based on functional graphene oxide (GO) and carboxyl-containing sulfonated poly(arylene ether ketone sulfone)s organic matrix (C-SPAEKS) were synthesized. Modified GO nanosheets (ATP@GO) was synthesized by using GO as a template, then chemically bonded adenosine triphosphate (ATP) on GO nanosheets. Modified ATP@GO and composite membranes were characterized by FT-IR, 1H NMR, SEM and XPS. These composite membranes exhibit outstanding proton conductivity, thermal stability and dimensional stability. Compared to C-SPAEKS membranes (32.3 mS cm−1 at 20 °C, 108.9 mS cm−1 at 90 °C), C-SPAEKS/ATP@GO-1 membrane showed enhanced proton conductivity (50.0 mS cm−1 at 20 °C, 184.8 mS cm−1 at 90 °C). Meanwhile, the open circuit voltage (OCV) and power density of C-SPAEKS/ATP@GO-1 were 0.9941 V and 466.33 mW/cm2, respectively, which were much higher than the C-SPAEKS (0.8973 V, 190.72 mW/cm2), showing good fuel cell performance. The results show that functionalized GO could make an important contribution to proton conduction and improvement of comprehensive performance in composite membrane, which indicate that these composite membranes have the potential to be used as PEMs. [ABSTRACT FROM AUTHOR]