The characteristics and mechanism of proton conduction in organic/inorganic composite membranes composed of sulfonated poly(ether sulfone) (SPES) and layered tin phosphate hydrates Sn(HPO 4 ) 2 · nH 2 O (SnP) were examined. SPES/SnP membranes were prepared by mixing 0-50 vol% of SnP with SPES solution and casting the mixture. Fourier-transform infrared, Raman, and solid-state 1 H NMR spectroscopy and thermogravimetric analysis showed that hydrogen-bond networks are formed between SPES and SnP in the composite membranes. At intermediate temperatures up to 150 • C, the membranes showed good proton-conducting properties, high chemical stability (low water solubility), and high thermal stability as a result of the formation of hydrogen bonds between SPES and SnP. The membrane containing 35 vol% SnP showed the highest conductivity of 8.1 × 10 −2 S cm −1 at 130 • C under saturated water vapor pressure. The membrane containing 25 vol% SnP showed a conductivity of 5.3 × 10 −2 S cm −1 at 130 • C under saturated water vapor pressure, despite its low water uptake. This membrane retained a high conductivity of 2.6 × 10 −3 S cm −1 at 130 • C at a low relative humidity of 40%, indicating that SPES/SnP membrane is a promising proton conductor at intermediate temperatures.The proton-exchange membrane fuel cell (PEMFC) is one of the most promising sources of alternative energy for transportation, stationary power, and portable electrical devices. For these diverse applications, it is important to enhance the kinetics of fuel oxidation and to suppress poisoning of the platinum electrocatalyst by carbon monoxide. 1 One approach to solving these problems is to increase the operating temperature to above 100 • C. Current industry-standard perfluorosulfonic polymers, such as Nafion, have a low heat resistance and a low glass-transition temperature, and their use is therefore limited to temperatures below 100 • C. Alternative sulfonated polymer membranes for use at intermediate temperatures have been widely studied, particularly sulfonated hydrocarbon polymers, such as sulfonated poly(ether ether ketone) (SPEEK) and sulfonated poly(ether sulfone) (SPES, including sulfonated polysulfone), which have high proton conductivities at intermediate temperatures, high thermal stabilities, and low costs. 2-6 It is known that the sulfonic acid (SO 3 H) groups in SPES have a high acidity because of the stronger electronwithdrawing nature of the SO 2 group in these polymers in comparison with those in other sulfonated hydrocarbon polymers, 7-9 which leads to a high proton conductivity. However, most such polymers exhibit marked decreases in proton conductivity under conditions of low relative humidity (RH) as a result of dehydration. 2, 3 Therefore, the attainment of a high proton conductivity (σ > 10 −2 S cm −1 ) at intermediate temperatures (above 100 • C) under conditions of low RH, in conjunction with a high chemical stability, is an important goal in the development of novel proton-conducting membranes.One possible approach to this goal is tha...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.